This documentation was generated automatically from the AVR Studio part description file `ATmega165.pdf`.

## TIMER COUNTER 0

### TCCR0A - Timer/Counter0 Control Register

`sfrb TCCR0A = $24;`

##### CS00 - Clock Select 1

`#define CS00_BIT 0`

`#define CS00_MASK 1`

The three clock select bits select the clock source to be used by the Timer/Counter,

##### CS01 - Clock Select 1

`#define CS01_BIT 1`

`#define CS01_MASK 2`

The three clock select bits select the clock source to be used by the Timer/Counter,

##### CS02 - Clock Select 2

`#define CS02_BIT 2`

`#define CS02_MASK 4`

The three clock select bits select the clock source to be used by the Timer/Counter,

##### WGM01 - Waveform Generation Mode 1

`#define WGM01_BIT 3`

`#define WGM01_MASK 8`

These bits control the counting sequence of the counter, the source for the maximum (TOP) counter value, and what type of waveform generation to be used. Modes of operation supported by the Timer/Counter unit are: Normal mode, Clear Timer on Compare match (CTC) mode, and two types of Pulse Width Modulation (PWM) modes. See Table 51 and ?Modes of Operation? on page 80.

##### COM0A0 - Compare match Output Mode 0

`#define COM0A0_BIT 4`

`#define COM0A0_MASK 16`

These bits control the output compare pin (OC0) behavior. If one or both of the COM01:0 bits are set, the OC0 output over-rides the normal port functionality of the I/O pin it is connected to. However, note that the Data Direction Register (DDR) bit corresponding to OC0 pin must be set in order to enable the output driver. When OC0 is connected to the pin, the function of the COM01:0 bits depends on the WGM01:0 bit setting. Table 52 shows the COM01:0 bit functionality when the WGM01:0 bits are set to a normal or CTC mode (non-PWM)

##### COM0A1 - Compare Match Output Mode 1

`#define COM0A1_BIT 5`

`#define COM0A1_MASK 32`

These bits control the output compare pin (OC0) behavior. If one or both of the COM01:0 bits are set, the OC0 output over-rides the normal port functionality of the I/O pin it is connected to. However, note that the Data Direction Register (DDR) bit corresponding to OC0 pin must be set in order to enable the output driver. When OC0 is connected to the pin, the function of the COM01:0 bits depends on the WGM01:0 bit setting. Table 52 shows the COM01:0 bit functionality when the WGM01:0 bits are set to a normal or CTC mode (non-PWM

##### WGM00 - Waveform Generation Mode 0

`#define WGM00_BIT 6`

`#define WGM00_MASK 64`

These bits control the counting sequence of the counter, the source for the maximum (TOP) counter value, and what type of waveform generation to be used. Modes of operation supported by the Timer/Counter unit are: Normal mode, Clear Timer on Compare match (CTC) mode, and two types of Pulse Width Modulation (PWM) modes. See Table 51 and ?Modes of Operation? on page 80.

##### FOC0A - Force Output Compare

`#define FOC0A_BIT 7`

`#define FOC0A_MASK 128`

The FOC0A bit is only active when the WGM bits specifies a non-PWM mode. However, for ensuring compatibility with future devices, this bit must be set to zero when TCCR0 is written when operating in PWM mode. When writing a logical one to the FOC0 bit, an immediate compare match is forced on the waveform generation unit. The OC0 output is changed accord-ing to its COM01:0 bits setting. Note that the FOC0 bit is implemented as a strobe. Therefore it is the value present in the COM01:0 bits that determines the effect of the forced compare. A FOC0 strobe will not generate any interrupt, nor will it clear the timer in CTC mode using OCR0 as TOP. The FOC0 bit is always read as ze

### TCNT0 - Timer/Counter0

`sfrb TCNT0 = $26;`

##### TCNT0_0

`#define TCNT0_0_BIT 0`

`#define TCNT0_0_MASK 1`

##### TCNT0_1

`#define TCNT0_1_BIT 1`

`#define TCNT0_1_MASK 2`

##### TCNT0_2

`#define TCNT0_2_BIT 2`

`#define TCNT0_2_MASK 4`

##### TCNT0_3

`#define TCNT0_3_BIT 3`

`#define TCNT0_3_MASK 8`

##### TCNT0_4

`#define TCNT0_4_BIT 4`

`#define TCNT0_4_MASK 16`

##### TCNT0_5

`#define TCNT0_5_BIT 5`

`#define TCNT0_5_MASK 32`

##### TCNT0_6

`#define TCNT0_6_BIT 6`

`#define TCNT0_6_MASK 64`

##### TCNT0_7

`#define TCNT0_7_BIT 7`

`#define TCNT0_7_MASK 128`

### OCR0A - Timer/Counter0 Output Compare Register

`sfrb OCR0A = $27;`

##### OCR0A0

`#define OCR0A0_BIT 0`

`#define OCR0A0_MASK 1`

##### OCR0A1

`#define OCR0A1_BIT 1`

`#define OCR0A1_MASK 2`

##### OCR0A2

`#define OCR0A2_BIT 2`

`#define OCR0A2_MASK 4`

##### OCR0A3

`#define OCR0A3_BIT 3`

`#define OCR0A3_MASK 8`

##### OCR0A4

`#define OCR0A4_BIT 4`

`#define OCR0A4_MASK 16`

##### OCR0A5

`#define OCR0A5_BIT 5`

`#define OCR0A5_MASK 32`

##### OCR0A6

`#define OCR0A6_BIT 6`

`#define OCR0A6_MASK 64`

##### OCR0A7

`#define OCR0A7_BIT 7`

`#define OCR0A7_MASK 128`

### TIMSK0 - Timer/Counter0 Interrupt Mask Register

`sfrb TIMSK0 = $6E;`

##### TOIE0 - Timer/Counter0 Overflow Interrupt Enable

`#define TOIE0_BIT 0`

`#define TOIE0_MASK 1`

When the TOIE0 bit is written to one, and the I-bit in the Status Register is set (one), the Timer/Counter0 Overflow interrupt is enabled. The corresponding interrupt is executed if an overflow in Timer/Counter0 occurs, i.e. when the TOV0 bit is set in the Timer/Counter Interrupt Flag Register - TIFR.

##### OCIE0A - Timer/Counter0 Output Compare Match Interrupt Enable

`#define OCIE0A_BIT 1`

`#define OCIE0A_MASK 2`

When the OCIE0 bit is written to one, and the I-bit in the Status Register is set (one), the Timer/Counter0 Compare Match interrupt is enabled. The corresponding interrupt is executed if a compare match in Timer/Counter0 occurs, i.e. when the OCF0 bit is set in the Timer/Counter Interrupt Flag Register - TIFR.

### TIFR0 - Timer/Counter0 Interrupt Flag register

`sfrb TIFR0 = $15;`

##### TOV0 - Timer/Counter0 Overflow Flag

`#define TOV0_BIT 0`

`#define TOV0_MASK 1`

The bit TOV0 is set (one) when an overflow occurs in Timer/Counter0. TOV0 is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, TOV0 is cleared by writing a logic one to the flag. When the SREG I-bit, TOIE0 (Timer/Counter0 Overflow Interrupt Enable), and TOV0 are set (one), the Timer/Counter0 Overflow interrupt is executed. In PWM mode, this bit is set when Timer/Counter0 changes counting direction at $00.

##### OCF0A - Timer/Counter0 Output Compare Flag 0

`#define OCF0A_BIT 1`

`#define OCF0A_MASK 2`

The OCF0 bit is set (one) when a compare match occurs between the Timer/Counter0 and the data in OCR0 - Output Compare Register0. OCF0 is cleared by hardware when executing the corresponding interrupt handling vector. Alterna-tively, OCF0 is cleared by writing a logic one to the flag. When the I-bit in SREG, OCIE0 (Timer/Counter0 Compare match Interrupt Enable), and OCF0 are set (one), the Timer/Counter0 Compare match Interrupt is executed.

### GTCCR - General Timer/Control Register

`sfrb GTCCR = $23;`

##### PSR310 - Prescaler Reset Timer/Counter1 and Timer/Counter0

`#define PSR310_BIT 0`

`#define PSR310_MASK 1`

When this bit is set (one)the Timer/Counter1 and Timer/Counter0 prescaler will be reset.The bit will be cleared by hard ware after the operation is performed.Writing a zero to this bit will have no effect.Note that Timer/Counter1 and Timer/Counter0 share the same prescaler and a reset of this prescaler will affect both timers.This bit will always be read as zero.

##### TSM - Timer/Counter Synchronization Mode

`#define TSM_BIT 7`

`#define TSM_MASK 128`

## TIMER COUNTER 1

### TCCR1A - Timer/Counter1 Control Register A

`sfrb TCCR1A = $80;`

##### WGM10 - Waveform Generation Mode

`#define WGM10_BIT 0`

`#define WGM10_MASK 1`

Combined with the WGM13:2 bits found in the TCCR1B register,these bits control the counting sequence of the counter, the source for maximum (TOP)counter value,and what type of waveform generation to be used.Modes of operation supported by the timer/counter unit are:Normal mode (counter),Clear Timer on Compare match (CTC)mode,and three types of Pulse Width Modulation (PWM)modes. PLease refer to the manual for a Mode Bit Description Table.

##### WGM11 - Waveform Generation Mode

`#define WGM11_BIT 1`

`#define WGM11_MASK 2`

Combined with the WGM13:2 bits found in the TCCR1B register,these bits control the counting sequence of the counter, the source for maximum (TOP)counter value,and what type of waveform generation to be used.Modes of operation supported by the timer/counter unit are:Normal mode (counter),Clear Timer on Compare match (CTC)mode,and three types of Pulse Width Modulation (PWM)modes. PLease refer to the manual for a Mode Bit Description Table.

##### COM1B0 - Compare Output Mode 1B, bit 0

`#define COM1B0_BIT 4`

`#define COM1B0_MASK 16`

The COM1B1 and COM1B0 control bits determine any output pin action following a compare match in Timer/Counter1. Any output pin actions affect pin OC1B - Output CompareB. This is an alternative function to an I/O port, and the corre-sponding direction control bit must be set (one) to control an output pin.

##### COM1B1 - Compare Output Mode 1B, bit 1

`#define COM1B1_BIT 5`

`#define COM1B1_MASK 32`

The COM1B1 and COM1B0 control bits determine any output pin action following a compare match in Timer/Counter1. Any output pin actions affect pin OC1B - Output CompareB. This is an alternative function to an I/O port, and the corre-sponding direction control bit must be set (one) to control an output pin.

##### COM1A0 - Compare Output Mode 1A, bit 0

`#define COM1A0_BIT 6`

`#define COM1A0_MASK 64`

The COM1A1 and COM1A0 control bits determine any output pin action following a compare match in Timer/Counter1. Any output pin actions affect pin OC1A - Output CompareA. This is an alternative function to an I/O port, and the corresponding direction control bit must be set (one) to control an output pin. The control configuration is shown in Table 10.

##### COM1A1 - Compare Output Mode 1A, bit 1

`#define COM1A1_BIT 7`

`#define COM1A1_MASK 128`

The COM1A1 and COM1A0 control bits determine any output pin action following a compare match in Timer/Counter1. Any output pin actions affect pin OC1A - Output CompareA. This is an alternative function to an I/O port, and the corresponding direction control bit must be set (one) to control an output pin. The control configuration is shown in Table 10.

### TCCR1B - Timer/Counter1 Control Register B

`sfrb TCCR1B = $81;`

##### CS10 - Prescaler source of Timer/Counter 1

`#define CS10_BIT 0`

`#define CS10_MASK 1`

Select Prescaling Clock Source of Timer/Counter1. (0:0:0) = Stop. (0:0:1) = CK. (0:1:0) = CK / 8. (0:1:1) = CK / 64. (1:0:0) = CK / 256. (1:0:1) = CK / 1024. (1:1:0) = External Pin T1, falling edge. (1:1:1) = External Pin 1, rising edge.

##### CS11 - Prescaler source of Timer/Counter 1

`#define CS11_BIT 1`

`#define CS11_MASK 2`

Select Prescaling Clock Source of Timer/Counter1. (0:0:0) = Stop. (0:0:1) = CK. (0:1:0) = CK / 8. (0:1:1) = CK / 64. (1:0:0) = CK / 256. (1:0:1) = CK / 1024. (1:1:0) = External Pin T1, falling edge. (1:1:1) = External Pin 1, rising edge.

##### CS12 - Prescaler source of Timer/Counter 1

`#define CS12_BIT 2`

`#define CS12_MASK 4`

Select Prescaling Clock Source of Timer/Counter1. (0:0:0) = Stop. (0:0:1) = CK. (0:1:0) = CK / 8. (0:1:1) = CK / 64. (1:0:0) = CK / 256. (1:0:1) = CK / 1024. (1:1:0) = External Pin T1, falling edge. (1:1:1) = External Pin 1, rising edge.

##### WGM12 - Waveform Generation Mode

`#define WGM12_BIT 3`

`#define WGM12_MASK 8`

Combined with the WGM13:2 bits found in the TCCR1B register,these bits control the counting sequence of the counter, the source for maximum (TOP)counter value,and what type of waveform generation to be used.Modes of operation supported by the timer/counter unit are:Normal mode (counter),Clear Timer on Compare match (CTC)mode,and three types of Pulse Width Modulation (PWM)modes. PLease refer to the manual for a Mode Bit Description Table.

##### WGM13 - Waveform Generation Mode

`#define WGM13_BIT 4`

`#define WGM13_MASK 16`

Combined with the WGM13:2 bits found in the TCCR1B register,these bits control the counting sequence of the counter, the source for maximum (TOP)counter value,and what type of waveform generation to be used.Modes of operation supported by the timer/counter unit are:Normal mode (counter),Clear Timer on Compare match (CTC)mode,and three types of Pulse Width Modulation (PWM)modes. PLease refer to the manual for a Mode Bit Description Table.

##### ICES1 - Input Capture 1 Edge Select

`#define ICES1_BIT 6`

`#define ICES1_MASK 64`

While the ICES1 bit is cleared (zero), the Timer/Counter1 contents are transferred to the Input Capture Register - ICR1 - on the falling edge of the input capture pin - ICP. While the ICES1 bit is set (one), the Timer/Counter1 contents are transferred to the Input Capture Register - ICR1 - on the rising edge of the input capture pin - ICP.

##### ICNC1 - Input Capture 1 Noise Canceler

`#define ICNC1_BIT 7`

`#define ICNC1_MASK 128`

When the ICNC1 bit is cleared (zero), the input capture trigger noise canceler function is disabled. The input capture is triggered at the first rising/falling edge sampled on the ICP - input capture pin - as specified. When the ICNC1 bit is set (one), four successive samples are measures on the ICP - input capture pin, and all samples must be high/low according to the input capture trigger specification in the ICES1 bit. The actual sampling frequency is XTAL clock frequency.

### TCCR1C - Timer/Counter 1 Control Register C

`sfrb TCCR1C = $82;`

##### FOC1B - Force Output Compare 1B

`#define FOC1B_BIT 6`

`#define FOC1B_MASK 64`

Writing a logical one to this bit, forces a change in the compare match output pin PD4 according to the values already set in COM1B1 and COM1B0.If the COM1B1 and COM1B0 bits are written in the same cycle as FOC1B,the new settings will not take effect until next compare match or forced compare match occurs. The Force Output Compare bit can be used to change the output pin without waiting for a compare match in the timer. The automatic action programmed in COM1B1 and COM1B0 happens as if a Compare Match had occurred, but no interrupt is generated. The corresponding I/O pin must be set as an output pin for the FOC1B bit to have effect on the pin. The FOC1B bit will always be read as zero. The setting of the FOC1B bit has no effect in PWM mo

##### FOC1A - Force Output Compare 1A

`#define FOC1A_BIT 7`

`#define FOC1A_MASK 128`

Writing a logical one to this bit, forces a change in the compare match output pin PD5 according to the values already set in COM1A1 and COM1A0.If the COM1A1 and COM1A0 bits are written in the same cycle as FOC1A,the new settings will not take effect until next compare match or forced compare match occurs. The Force Output Compare bit can be used to change the output pin without waiting for a compare match in the timer. The automatic action programmed in COM1A1 and COM1A0 happens as if a Compare Match had occurred, but no interrupt is generated and it will not clear the timer even if CTC1 in TCCR1B is set. The corresponding I/O pin must be set as an output pin for the FOC1A bit to have effect on the pin. The FOC1A bit will always be read as zero. The setting of the FOC1A bit has no effect in PWM m

### TCNT1H - Timer/Counter1 High Byte

`sfrb TCNT1H = $85;`

##### TCNT1H0 - Timer/Counter1 High Byte bit 0

`#define TCNT1H0_BIT 0`

`#define TCNT1H0_MASK 1`

##### TCNT1H1 - Timer/Counter1 High Byte bit 1

`#define TCNT1H1_BIT 1`

`#define TCNT1H1_MASK 2`

##### TCNT1H2 - Timer/Counter1 High Byte bit 2

`#define TCNT1H2_BIT 2`

`#define TCNT1H2_MASK 4`

##### TCNT1H3 - Timer/Counter1 High Byte bit 3

`#define TCNT1H3_BIT 3`

`#define TCNT1H3_MASK 8`

##### TCNT1H4 - Timer/Counter1 High Byte bit 4

`#define TCNT1H4_BIT 4`

`#define TCNT1H4_MASK 16`

##### TCNT1H5 - Timer/Counter1 High Byte bit 5

`#define TCNT1H5_BIT 5`

`#define TCNT1H5_MASK 32`

##### TCNT1H6 - Timer/Counter1 High Byte bit 6

`#define TCNT1H6_BIT 6`

`#define TCNT1H6_MASK 64`

##### TCNT1H7 - Timer/Counter1 High Byte bit 7

`#define TCNT1H7_BIT 7`

`#define TCNT1H7_MASK 128`

### TCNT1L - Timer/Counter1 Low Byte

`sfrb TCNT1L = $84;`

##### TCNT1L0 - Timer/Counter1 Low Byte bit 0

`#define TCNT1L0_BIT 0`

`#define TCNT1L0_MASK 1`

##### TCNT1L1 - Timer/Counter1 Low Byte bit 1

`#define TCNT1L1_BIT 1`

`#define TCNT1L1_MASK 2`

##### TCNT1L2 - Timer/Counter1 Low Byte bit 2

`#define TCNT1L2_BIT 2`

`#define TCNT1L2_MASK 4`

##### TCNT1L3 - Timer/Counter1 Low Byte bit 3

`#define TCNT1L3_BIT 3`

`#define TCNT1L3_MASK 8`

##### TCNT1L4 - Timer/Counter1 Low Byte bit 4

`#define TCNT1L4_BIT 4`

`#define TCNT1L4_MASK 16`

##### TCNT1L5 - Timer/Counter1 Low Byte bit 5

`#define TCNT1L5_BIT 5`

`#define TCNT1L5_MASK 32`

##### TCNT1L6 - Timer/Counter1 Low Byte bit 6

`#define TCNT1L6_BIT 6`

`#define TCNT1L6_MASK 64`

##### TCNT1L7 - Timer/Counter1 Low Byte bit 7

`#define TCNT1L7_BIT 7`

`#define TCNT1L7_MASK 128`

### OCR1AH - Timer/Counter1 Outbut Compare Register A High Byte

`sfrb OCR1AH = $89;`

##### OCR1AH0 - Timer/Counter1 Outbut Compare Register High Byte bit 0

`#define OCR1AH0_BIT 0`

`#define OCR1AH0_MASK 1`

##### OCR1AH1 - Timer/Counter1 Outbut Compare Register High Byte bit 1

`#define OCR1AH1_BIT 1`

`#define OCR1AH1_MASK 2`

##### OCR1AH2 - Timer/Counter1 Outbut Compare Register High Byte bit 2

`#define OCR1AH2_BIT 2`

`#define OCR1AH2_MASK 4`

##### OCR1AH3 - Timer/Counter1 Outbut Compare Register High Byte bit 3

`#define OCR1AH3_BIT 3`

`#define OCR1AH3_MASK 8`

##### OCR1AH4 - Timer/Counter1 Outbut Compare Register High Byte bit 4

`#define OCR1AH4_BIT 4`

`#define OCR1AH4_MASK 16`

##### OCR1AH5 - Timer/Counter1 Outbut Compare Register High Byte bit 5

`#define OCR1AH5_BIT 5`

`#define OCR1AH5_MASK 32`

##### OCR1AH6 - Timer/Counter1 Outbut Compare Register High Byte bit 6

`#define OCR1AH6_BIT 6`

`#define OCR1AH6_MASK 64`

##### OCR1AH7 - Timer/Counter1 Outbut Compare Register High Byte bit 7

`#define OCR1AH7_BIT 7`

`#define OCR1AH7_MASK 128`

### OCR1AL - Timer/Counter1 Outbut Compare Register A Low Byte

`sfrb OCR1AL = $88;`

##### OCR1AL0 - Timer/Counter1 Outbut Compare Register Low Byte Bit 0

`#define OCR1AL0_BIT 0`

`#define OCR1AL0_MASK 1`

##### OCR1AL1 - Timer/Counter1 Outbut Compare Register Low Byte Bit 1

`#define OCR1AL1_BIT 1`

`#define OCR1AL1_MASK 2`

##### OCR1AL2 - Timer/Counter1 Outbut Compare Register Low Byte Bit 2

`#define OCR1AL2_BIT 2`

`#define OCR1AL2_MASK 4`

##### OCR1AL3 - Timer/Counter1 Outbut Compare Register Low Byte Bit 3

`#define OCR1AL3_BIT 3`

`#define OCR1AL3_MASK 8`

##### OCR1AL4 - Timer/Counter1 Outbut Compare Register Low Byte Bit 4

`#define OCR1AL4_BIT 4`

`#define OCR1AL4_MASK 16`

##### OCR1AL5 - Timer/Counter1 Outbut Compare Register Low Byte Bit 5

`#define OCR1AL5_BIT 5`

`#define OCR1AL5_MASK 32`

##### OCR1AL6 - Timer/Counter1 Outbut Compare Register Low Byte Bit 6

`#define OCR1AL6_BIT 6`

`#define OCR1AL6_MASK 64`

##### OCR1AL7 - Timer/Counter1 Outbut Compare Register Low Byte Bit 7

`#define OCR1AL7_BIT 7`

`#define OCR1AL7_MASK 128`

### OCR1BH - Timer/Counter1 Output Compare Register B High Byte

`sfrb OCR1BH = $8B;`

##### OCR1BH0 - Timer/Counter1 Output Compare Register High Byte bit 0

`#define OCR1BH0_BIT 0`

`#define OCR1BH0_MASK 1`

##### OCR1BH1 - Timer/Counter1 Output Compare Register High Byte bit 1

`#define OCR1BH1_BIT 1`

`#define OCR1BH1_MASK 2`

##### OCR1BH2 - Timer/Counter1 Output Compare Register High Byte bit 2

`#define OCR1BH2_BIT 2`

`#define OCR1BH2_MASK 4`

##### OCR1BH3 - Timer/Counter1 Output Compare Register High Byte bit 3

`#define OCR1BH3_BIT 3`

`#define OCR1BH3_MASK 8`

##### OCR1BH4 - Timer/Counter1 Output Compare Register High Byte bit 4

`#define OCR1BH4_BIT 4`

`#define OCR1BH4_MASK 16`

##### OCR1BH5 - Timer/Counter1 Output Compare Register High Byte bit 5

`#define OCR1BH5_BIT 5`

`#define OCR1BH5_MASK 32`

##### OCR1BH6 - Timer/Counter1 Output Compare Register High Byte bit 6

`#define OCR1BH6_BIT 6`

`#define OCR1BH6_MASK 64`

##### OCR1BH7 - Timer/Counter1 Output Compare Register High Byte bit 7

`#define OCR1BH7_BIT 7`

`#define OCR1BH7_MASK 128`

### OCR1BL - Timer/Counter1 Output Compare Register B Low Byte

`sfrb OCR1BL = $8A;`

##### OCR1BL0 - Timer/Counter1 Output Compare Register Low Byte bit 0

`#define OCR1BL0_BIT 0`

`#define OCR1BL0_MASK 1`

##### OCR1BL1 - Timer/Counter1 Output Compare Register Low Byte bit 1

`#define OCR1BL1_BIT 1`

`#define OCR1BL1_MASK 2`

##### OCR1BL2 - Timer/Counter1 Output Compare Register Low Byte bit 2

`#define OCR1BL2_BIT 2`

`#define OCR1BL2_MASK 4`

##### OCR1BL3 - Timer/Counter1 Output Compare Register Low Byte bit 3

`#define OCR1BL3_BIT 3`

`#define OCR1BL3_MASK 8`

##### OCR1BL4 - Timer/Counter1 Output Compare Register Low Byte bit 4

`#define OCR1BL4_BIT 4`

`#define OCR1BL4_MASK 16`

##### OCR1BL5 - Timer/Counter1 Output Compare Register Low Byte bit 5

`#define OCR1BL5_BIT 5`

`#define OCR1BL5_MASK 32`

##### OCR1BL6 - Timer/Counter1 Output Compare Register Low Byte bit 6

`#define OCR1BL6_BIT 6`

`#define OCR1BL6_MASK 64`

##### OCR1BL7 - Timer/Counter1 Output Compare Register Low Byte bit 7

`#define OCR1BL7_BIT 7`

`#define OCR1BL7_MASK 128`

### ICR1H - Timer/Counter1 Input Capture Register High Byte

`sfrb ICR1H = $87;`

##### ICR1H0 - Timer/Counter1 Input Capture Register High Byte bit 0

`#define ICR1H0_BIT 0`

`#define ICR1H0_MASK 1`

##### ICR1H1 - Timer/Counter1 Input Capture Register High Byte bit 1

`#define ICR1H1_BIT 1`

`#define ICR1H1_MASK 2`

##### ICR1H2 - Timer/Counter1 Input Capture Register High Byte bit 2

`#define ICR1H2_BIT 2`

`#define ICR1H2_MASK 4`

##### ICR1H3 - Timer/Counter1 Input Capture Register High Byte bit 3

`#define ICR1H3_BIT 3`

`#define ICR1H3_MASK 8`

##### ICR1H4 - Timer/Counter1 Input Capture Register High Byte bit 4

`#define ICR1H4_BIT 4`

`#define ICR1H4_MASK 16`

##### ICR1H5 - Timer/Counter1 Input Capture Register High Byte bit 5

`#define ICR1H5_BIT 5`

`#define ICR1H5_MASK 32`

##### ICR1H6 - Timer/Counter1 Input Capture Register High Byte bit 6

`#define ICR1H6_BIT 6`

`#define ICR1H6_MASK 64`

##### ICR1H7 - Timer/Counter1 Input Capture Register High Byte bit 7

`#define ICR1H7_BIT 7`

`#define ICR1H7_MASK 128`

### ICR1L - Timer/Counter1 Input Capture Register Low Byte

`sfrb ICR1L = $86;`

##### ICR1L0 - Timer/Counter1 Input Capture Register Low Byte bit 0

`#define ICR1L0_BIT 0`

`#define ICR1L0_MASK 1`

##### ICR1L1 - Timer/Counter1 Input Capture Register Low Byte bit 1

`#define ICR1L1_BIT 1`

`#define ICR1L1_MASK 2`

##### ICR1L2 - Timer/Counter1 Input Capture Register Low Byte bit 2

`#define ICR1L2_BIT 2`

`#define ICR1L2_MASK 4`

##### ICR1L3 - Timer/Counter1 Input Capture Register Low Byte bit 3

`#define ICR1L3_BIT 3`

`#define ICR1L3_MASK 8`

##### ICR1L4 - Timer/Counter1 Input Capture Register Low Byte bit 4

`#define ICR1L4_BIT 4`

`#define ICR1L4_MASK 16`

##### ICR1L5 - Timer/Counter1 Input Capture Register Low Byte bit 5

`#define ICR1L5_BIT 5`

`#define ICR1L5_MASK 32`

##### ICR1L6 - Timer/Counter1 Input Capture Register Low Byte bit 6

`#define ICR1L6_BIT 6`

`#define ICR1L6_MASK 64`

##### ICR1L7 - Timer/Counter1 Input Capture Register Low Byte bit 7

`#define ICR1L7_BIT 7`

`#define ICR1L7_MASK 128`

### TIMSK1 - Timer/Counter1 Interrupt Mask Register

`sfrb TIMSK1 = $6F;`

##### TOIE1 - Timer/Counter1 Overflow Interrupt Enable

`#define TOIE1_BIT 0`

`#define TOIE1_MASK 1`

When the TOIE1 bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter1 Overflow interrupt is enabled. The corresponding interrupt (at vector $006) is executed if an overflow in Timer/Counter1 occurs, i.e., when the TOV1 bit is set in the Timer/Counter Interrupt Flag Register - TIFR.

##### OCIE1A - Timer/Counter1 Output Compare A Match Interrupt Enable

`#define OCIE1A_BIT 1`

`#define OCIE1A_MASK 2`

When the OCIE1A bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter1 CompareA Match interrupt is enabled. The corresponding interrupt (at vector $004) is executed if a CompareA match in Timer/Counter1 occurs, i.e., when the OCF1A bit is set in the Timer/Counter Interrupt Flag Register - TIFR.

##### OCIE1B - Timer/Counter1 Output Compare B Match Interrupt Enable

`#define OCIE1B_BIT 2`

`#define OCIE1B_MASK 4`

When the OCIE1B bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter1 CompareB Match interrupt is enabled. The corresponding interrupt (at vector $005) is executed if a CompareB match in Timer/Counter1 occurs, i.e., when the OCF1B bit is set in the Timer/Counter Interrupt Flag Register - TIFR.

##### ICIE1 - Timer/Counter1 Input Capture Interrupt Enable

`#define ICIE1_BIT 5`

`#define ICIE1_MASK 32`

When the TICIE1 bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter1 Input Capture Event Interrupt is enabled. The corresponding interrupt (at vector $003) is executed if a capture-triggering event occurs on pin 31, ICP, i.e., when the ICF1 bit is set in the Timer/Counter Interrupt Flag Register - TIFR.

### TIFR1 - Timer/Counter1 Interrupt Flag register

`sfrb TIFR1 = $16;`

##### TOV1 - Timer/Counter1 Overflow Flag

`#define TOV1_BIT 0`

`#define TOV1_MASK 1`

The TOV1 is set (one) when an overflow occurs in Timer/Counter1. TOV1 is cleared by hardware when executing the cor-responding interrupt handling vector. Alternatively, TOV1 is cleared by writing a logic one to the flag. When the I-bit in SREG, and TOIE1 (Timer/Counter1 Overflow Interrupt Enable), and TOV1 are set (one), the Timer/Counter1 Overflow Interrupt is executed. In PWM mode, this bit is set when Timer/Counter1 changes counting direction at $0000.

##### OCF1A - Output Compare Flag 1A

`#define OCF1A_BIT 1`

`#define OCF1A_MASK 2`

The OCF1A bit is set (one) when compare match occurs between the Timer/Counter1 and the data in OCR1A - Output Compare Register 1A. OCF1A is cleared by hardware when executing the corresponding interrupt handling vector. Alterna-tively, OCF1A is cleared by writing a logic one to the flag. When the I-bit in SREG, and OCIE1A (Timer/Counter1 Compare match InterruptA Enable), and the OCF1A are set (one), the Timer/Counter1 Compare A match Interrupt is executed.

##### OCF1B - Output Compare Flag 1B

`#define OCF1B_BIT 2`

`#define OCF1B_MASK 4`

The OCF1B bit is set (one) when compare match occurs between the Timer/Counter1 and the data in OCR1B - Output Compare Register 1B. OCF1B is cleared by hardware when executing the corresponding interrupt handling vector. Alterna-tively, OCF1B is cleared by writing a logic one to the flag. When the I-bit in SREG, and OCIE1B (Timer/Counter1 Compare match InterruptB Enable), and the OCF1B are set (one), the Timer/Counter1 Compare B match Interrupt is executed.

##### ICF1 - Input Capture Flag 1

`#define ICF1_BIT 5`

`#define ICF1_MASK 32`

The ICF1 bit is set (one) to flag an input capture event, indicating that the Timer/Counter1 value has been transferred to the input capture register - ICR1. ICF1 is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ICF1 is cleared by writing a logic one to the flag. When the SREG I-bit, and TICIE1 (Timer/Counter1 Input Capture Interrupt Enable), and ICF1 are set (one), the Timer/Counter1 Capture Interrupt is executed.

## TIMER COUNTER 2

The 8-bit Timer/Counter2 can select clock source from CK, prescaled CK, or external crystal input TOSC1. It can also be stopped as described in the section ?Timer/Counter2 Control Register - TCCR2?. The status flags (overflow and compare match) are found in the Timer/Counter Interrupt Flag Register - TIFR. Control signals are found in the Timer/Counter Control Register TCCR2. The interrupt enable/disable settings are found in ?The Timer/Counter Interrupt Mask Register - TIMSK?. When Timer/Counter2 is externally clocked, the external signal is synchronized with the oscillator frequency of the CPU. To assure proper sampling of the external clock, the minimum time between two external clock transitions must be at least one internal CPU clock period. The external clock signal is sampled on the rising edge of the internal CPU clock. This module features a high resolution and a high accuracy usage with the lower prescaling opportunities. Similarly, the high prescaling opportunities make this unit useful for lower speed functions or exact timing functions with infrequent actions. Timer/Counter2 can also be used as an 8-bit Pulse Width Modulator. In this mode, Timer/Counter2 and the output compare register serve as a glitch-free, stand-alone PWM with centered puls

### TCCR2A - Timer/Counter2 Control Register

`sfrb TCCR2A = $B0;`

##### CS20 - Clock Select bit 0

`#define CS20_BIT 0`

`#define CS20_MASK 1`

The Clock Select bits 2,1, and 0 define the prescaling source of Timer/Counter2. (CS22:CS21:CS20) Description. (0:0:0) Timer/Counter2 is stopped. (0:0:1) PCK2. (0:1:0) PCK2/8. (0:1:1) PCK2/32. (1:0:0) PCK2/64. (1:0:1) PCK2/128. (1:1:0) PCK2/256. (1:1:1) PCK2/1024. The Stop condition provides a Timer Enable/Disable function. The prescaled modes are scaled directly from the PCK2 clock.

##### CS21 - Clock Select bit 1

`#define CS21_BIT 1`

`#define CS21_MASK 2`

The Clock Select bits 2,1, and 0 define the prescaling source of Timer/Counter2. (CS22:CS21:CS20) Description. (0:0:0) Timer/Counter2 is stopped. (0:0:1) PCK2. (0:1:0) PCK2/8. (0:1:1) PCK2/32. (1:0:0) PCK2/64. (1:0:1) PCK2/128. (1:1:0) PCK2/256. (1:1:1) PCK2/1024. The Stop condition provides a Timer Enable/Disable function. The prescaled modes are scaled directly from the PCK2 clock.

##### CS22 - Clock Select bit 2

`#define CS22_BIT 2`

`#define CS22_MASK 4`

The Clock Select bits 2,1, and 0 define the prescaling source of Timer/Counter2. (CS22:CS21:CS20) Description. (0:0:0) Timer/Counter2 is stopped. (0:0:1) PCK2. (0:1:0) PCK2/8. (0:1:1) PCK2/32. (1:0:0) PCK2/64. (1:0:1) PCK2/128. (1:1:0) PCK2/256. (1:1:1) PCK2/1024. The Stop condition provides a Timer Enable/Disable function. The prescaled modes are scaled directly from the PCK2 clock.

##### WGM21 - Waveform Generation Mode

`#define WGM21_BIT 3`

`#define WGM21_MASK 8`

These bits control the counting sequence of the counter,the source for hte maximum (TOP)counter value,and what type of waveform generation to be used.Modes of operation supported by the timer/counter unit are:Normal mode (counter), Clear Timer on Compare match (CTC)mode,and two types of Pulse Width Modulation (PWM)modes. Please refer to the manual for more information.

##### COM2A0 - Compare Output Mode bit 0

`#define COM2A0_BIT 4`

`#define COM2A0_MASK 16`

The COM21 and COM20 control bits determine any output pin action following a compare match in Timer/Counter2. Output pin actions affect pin PD7(OC2). This is an alternative function to an I/O port, and the corresponding direction control bit must be set (one) to control an output pin. (COM21:COM20) description: (0:0) = Timer/Counter disconnected from output pin OC2. (0:1) = Toggle the OC2 output line. (1:0) = Clear the OC2 output line (to zero). (1:1) = Set the OC2 output line (to one). Note: In PWM mode, these bits have a different function

##### COM2A1 - Compare Output Mode bit 1

`#define COM2A1_BIT 5`

`#define COM2A1_MASK 32`

The COM21 and COM20 control bits determine any output pin action following a compare match in Timer/Counter2. Output pin actions affect pin PD7(OC2). This is an alternative function to an I/O port, and the corresponding direction control bit must be set (one) to control an output pin. (COM21:COM20) description: (0:0) = Timer/Counter disconnected from output pin OC2. (0:1) = Toggle the OC2 output line. (1:0) = Clear the OC2 output line (to zero). (1:1) = Set the OC2 output line (to one). Note: In PWM mode, these bits have a different function

##### WGM20 - Waveform Generation Mode

`#define WGM20_BIT 6`

`#define WGM20_MASK 64`

These bits control the counting sequence of the counter,the source for hte maximum (TOP)counter value,and what type of waveform generation to be used.Modes of operation supported by the timer/counter unit are:Normal mode (counter), Clear Timer on Compare match (CTC)mode,and two types of Pulse Width Modulation (PWM)modes. Please refer to the manual for more information.

##### FOC2A - Force Output Compare A

`#define FOC2A_BIT 7`

`#define FOC2A_MASK 128`

Writing a logical one to this bit, forces a change in the compare match output pin OC2 according to the values already set in COM21 and COM20. If the COM21 and COM20 bits are written in the same cycle as FOC2, the new settings will not take effect until next compare match or forced output compare match occurs. The Force Output Compare bit can be used to change the output pin without waiting for a compare match in the timer. The automatic action programmed in COM21 and COM20 happens as if a Compare Match had occurred, but no interrupt is generated, and the Timer/Counter will not be cleared even if CTC2 is set. The corresponding I/O pin must be set as an output pin for the FOC2 bit to have effect on the pin. The FOC2 bit will always be read as zero. Setting the FOC2 bit has no effect in PWM mod

### TCNT2 - Timer/Counter2

`sfrb TCNT2 = $B2;`

##### TCNT2-0 - Timer/Counter 2 bit 0

`#define TCNT2-0_BIT 0`

`#define TCNT2-0_MASK 1`

##### TCNT2-1 - Timer/Counter 2 bit 1

`#define TCNT2-1_BIT 1`

`#define TCNT2-1_MASK 2`

##### TCNT2-2 - Timer/Counter 2 bit 2

`#define TCNT2-2_BIT 2`

`#define TCNT2-2_MASK 4`

##### TCNT2-3 - Timer/Counter 2 bit 3

`#define TCNT2-3_BIT 3`

`#define TCNT2-3_MASK 8`

##### TCNT2-4 - Timer/Counter 2 bit 4

`#define TCNT2-4_BIT 4`

`#define TCNT2-4_MASK 16`

##### TCNT2-5 - Timer/Counter 2 bit 5

`#define TCNT2-5_BIT 5`

`#define TCNT2-5_MASK 32`

##### TCNT2-6 - Timer/Counter 2 bit 6

`#define TCNT2-6_BIT 6`

`#define TCNT2-6_MASK 64`

##### TCNT2-7 - Timer/Counter 2 bit 7

`#define TCNT2-7_BIT 7`

`#define TCNT2-7_MASK 128`

### OCR2A - Timer/Counter2 Output Compare Register

`sfrb OCR2A = $B3;`

##### OCR2A0 - Timer/Counter2 Output Compare Register Bit 0

`#define OCR2A0_BIT 0`

`#define OCR2A0_MASK 1`

##### OCR2A1 - Timer/Counter2 Output Compare Register Bit 1

`#define OCR2A1_BIT 1`

`#define OCR2A1_MASK 2`

##### OCR2A2 - Timer/Counter2 Output Compare Register Bit 2

`#define OCR2A2_BIT 2`

`#define OCR2A2_MASK 4`

##### OCR2A3 - Timer/Counter2 Output Compare Register Bit 3

`#define OCR2A3_BIT 3`

`#define OCR2A3_MASK 8`

##### OCR2A4 - Timer/Counter2 Output Compare Register Bit 4

`#define OCR2A4_BIT 4`

`#define OCR2A4_MASK 16`

##### OCR2A5 - Timer/Counter2 Output Compare Register Bit 5

`#define OCR2A5_BIT 5`

`#define OCR2A5_MASK 32`

##### OCR2A6 - Timer/Counter2 Output Compare Register Bit 6

`#define OCR2A6_BIT 6`

`#define OCR2A6_MASK 64`

##### OCR2A7 - Timer/Counter2 Output Compare Register Bit 7

`#define OCR2A7_BIT 7`

`#define OCR2A7_MASK 128`

### TIMSK2 - Timer/Counter2 Interrupt Mask register

`sfrb TIMSK2 = $70;`

##### TOIE2 - Timer/Counter2 Overflow Interrupt Enable

`#define TOIE2_BIT 0`

`#define TOIE2_MASK 1`

When the TOIE2 bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter2 Overflow interrupt is

##### OCIE2A - Timer/Counter2 Output Compare Match Interrupt Enable

`#define OCIE2A_BIT 1`

`#define OCIE2A_MASK 2`

When the OCIE2 bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter2 Compare Match interrupt is enabled. The corresponding interrupt (at vector $006) is executed if a compare match in Timer/Counter2 occurs, i.e. when the OCF2 bit is set in the Timer/Counter Interrupt Flag Register - TIFR.

### TIFR2 - Timer/Counter2 Interrupt Flag Register

`sfrb TIFR2 = $17;`

##### TOV2 - Timer/Counter2 Overflow Flag

`#define TOV2_BIT 0`

`#define TOV2_MASK 1`

The TOV2 bit is set (one) when an overflow occurs in Timer/Counter2. TOV2 is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, TOV2 is cleared by writing a logic one to the flag. When the SREG I-bit, and TOIE2 (Timer/Counter2 Overflow Interrupt Enable), and TOV2 are set (one), the Timer/Counter2 Overflow interrupt is executed. In up/down PWM mode, this bit is set when Timer/Counter2 changes counting direction at $00.

##### OCF2A - Timer/Counter2 Output Compare Flag 2

`#define OCF2A_BIT 1`

`#define OCF2A_MASK 2`

The OCF2 bit is set (one) when a compare match occurs between the Timer/Counter2 and the data in OCR2 - Output Compare Register2. OCF2 is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, OCF2 is cleared by writing a logic one to the flag. When the I-bit in SREG, and OCIE2 (Timer/Counter2 Compare match Interrupt Enable), and the OCF2 are set (one), the Timer/Counter2 Compare match Interrupt is executed.

### GTCCR - General Timer/Counter Control Register

`sfrb GTCCR = $23;`

##### PSR2 - Prescaler Reset Timer/Counter2

`#define PSR2_BIT 1`

`#define PSR2_MASK 2`

When this bit is set (one)the Timer/Counter2 prescaler will be reset.The bit will be cleared by hardware after the operation is performed.Writing a zero to this bit will have no effect.This bit will always be read as zero if Timer/Counter2 is clocked by the internal CPU clock.If this bit is written when Timer/Counter2 is operating in asynchronous mode,the bit will remain one until the prescaler has been reset.

### ASSR - Asynchronous Status Register

`sfrb ASSR = $B6;`

##### TCR2UB - TCR2UB: Timer/Counter Control Register2 Update Busy

`#define TCR2UB_BIT 0`

`#define TCR2UB_MASK 1`

When Timer/Counter2 operates asynchronously and TCCR2A is written, this bit becomes set. When TCCR2A has been updated from the temporary storage register, this bit is cleared by hardware. A logical zero in this bit indicates that TCCR2A is ready to be updated with a new value. If a write is performed to any of the three Timer/Counter2 Registers while its update busy flag is set, the updated value might get corrupted and cause an unintentional inter-rupt to occur. The mechanisms for reading TCNT2, OCR2A, and TCCR2A are different. When read-ing TCNT2, the actual timer value is read. When reading OCR2A or TCCR2A, the value in the temporary storage register is r

##### OCR2UB - Output Compare Register2 Update Busy

`#define OCR2UB_BIT 1`

`#define OCR2UB_MASK 2`

When Timer/Counter2 operates asynchronously and OCR2A is written, this bit becomes set. When OCR2A has been updated from the temporary storage register, this bit is cleared by hardware. A logical zero in this bit indicates that OCR2A is ready to be updated with a new value.

##### TCN2UB - TCN2UB: Timer/Counter2 Update Busy

`#define TCN2UB_BIT 2`

`#define TCN2UB_MASK 4`

When Timer/Counter2 operates asynchronously and TCNT2 is written, this bit becomes set. When TCNT2 has been updated from the temporary storage register, this bit is cleared by hardware. A logical zero in this bit indicates that TCNT2 is ready to be updated with a new value.

##### AS2 - AS2: Asynchronous Timer/Counter2

`#define AS2_BIT 3`

`#define AS2_MASK 8`

When AS2 is written to zero, Timer/Counter2 is clocked from the I/O clock, clk I/O . When AS2 is written to one, Timer/Counter2 is clocked from a crystal Oscillator connected to the Timer Oscillator 1 (TOSC1) pin. When the value of AS2 is changed, the contents of TCNT2, OCR2A, and TCCR2A might be corrupted.

##### EXCLK - Enable External Clock Interrupt

`#define EXCLK_BIT 4`

`#define EXCLK_MASK 16`

When EXCLK is written to one, and asynchronous clock is selected, the external clock input buffer is enabled and an external clock can be input on Timer Oscillator 1 (TOSC1) pin instead of a 32 kHz crystal. Writing to EXCLK should be done before asynchronous operation is selected. Note that the crystal Oscillator will only run when this bit is zero.

## WATCHDOG

### WDTCR - Watchdog Timer Control Register

`sfrb WDTCR = $60;`

##### WDP0 - Watch Dog Timer Prescaler bit 0

`#define WDP0_BIT 0`

`#define WDP0_MASK 1`

The WDP2,WDP1,and WDP0 bits determine the Watchdog Timer prescaling when the Watchdog Timer is enabled.

##### WDP1 - Watch Dog Timer Prescaler bit 1

`#define WDP1_BIT 1`

`#define WDP1_MASK 2`

The WDP2,WDP1,and WDP0 bits determine the Watchdog Timer prescaling when the Watchdog Timer is enabled.

##### WDP2 - Watch Dog Timer Prescaler bit 2

`#define WDP2_BIT 2`

`#define WDP2_MASK 4`

The WDP2,WDP1,and WDP0 bits determine the Watchdog Timer prescaling when the Watchdog Timer is enabled.

##### WDE - Watch Dog Enable

`#define WDE_BIT 3`

`#define WDE_MASK 8`

When the WDE is set (one) the Watchdog Timer is enabled, and if the WDE is cleared (zero) the Watchdog Timer function is disabled. WDE can only be cleared if the WDTOE bit is set(one). To disable an enabled watchdog timer, the following procedure must be followed: 1. In the same operation, write a logical one to WDTOE and WDE. A logical one must be written to WDE even though it is set to one before the disable operation starts. 2. Within the next four clock cycles, write a logical 0 to WDE. This disables the watchdog

##### WDCE - Watchdog Change Enable

`#define WDCE_BIT 4`

`#define WDCE_MASK 16`

This bit must be set when the WDE bit is written to logic zero.Otherwise,the watchdog will not be disabled.Once written to one,hardware will clear this bit after four clock cycles.Refer to the description of the WDE bit for a watchdog disable procedure.This bit must also be set when changing the prescaler bits.

## EEPROM

EEPROM Read/Write Access. The EEPROM access registers are accessible in the I/O space. The write access time for the EEPROM is given in Table 1. A self-timing function, however, lets the user software detect when the next byte can be written. If the user code contains instructions that write the EEPROM, some precautions must be taken. In heavily filtered power supplies, V CC is likely to rise or fall slowly on power-up/down. This causes the device for some period of time to run at a voltage lower than specified as minimum for the clock frequency used. See ?Preventing EEPROM Corruption? on page 19. for details on how to avoid problems in these situations.In order to prevent unintentional EEPROM writes, a specific write procedure must be followed. Refer to the description of the EEPROM Control Register for details on this. When the EEPROM is read, the CPU is halted for four clock cycles before the next instruction is executed. When theEEPROM is written, the CPU is halted for two clock cycles before the next instruction is execute

### EEARH - EEPROM Address Register High Byte

`sfrb EEARH = $22;`

##### EEAR8 - EEPROM Read/Write Access Bit 8

`#define EEAR8_BIT 0`

`#define EEAR8_MASK 1`

### EEARL - EEPROM Address Register Low Byte

`sfrb EEARL = $21;`

##### EEAR0 - EEPROM Read/Write Access Bit 0

`#define EEAR0_BIT 0`

`#define EEAR0_MASK 1`

##### EEAR1 - EEPROM Read/Write Access Bit 1

`#define EEAR1_BIT 1`

`#define EEAR1_MASK 2`

##### EEAR2 - EEPROM Read/Write Access Bit 2

`#define EEAR2_BIT 2`

`#define EEAR2_MASK 4`

##### EEAR3 - EEPROM Read/Write Access Bit 3

`#define EEAR3_BIT 3`

`#define EEAR3_MASK 8`

##### EEAR4 - EEPROM Read/Write Access Bit 4

`#define EEAR4_BIT 4`

`#define EEAR4_MASK 16`

##### EEAR5 - EEPROM Read/Write Access Bit 5

`#define EEAR5_BIT 5`

`#define EEAR5_MASK 32`

##### EEAR6 - EEPROM Read/Write Access Bit 6

`#define EEAR6_BIT 6`

`#define EEAR6_MASK 64`

##### EEAR7 - EEPROM Read/Write Access Bit 7

`#define EEAR7_BIT 7`

`#define EEAR7_MASK 128`

### EEDR - EEPROM Data Register

`sfrb EEDR = $20;`

##### EEDR0 - EEPROM Data Register bit 0

`#define EEDR0_BIT 0`

`#define EEDR0_MASK 1`

##### EEDR1 - EEPROM Data Register bit 1

`#define EEDR1_BIT 1`

`#define EEDR1_MASK 2`

##### EEDR2 - EEPROM Data Register bit 2

`#define EEDR2_BIT 2`

`#define EEDR2_MASK 4`

##### EEDR3 - EEPROM Data Register bit 3

`#define EEDR3_BIT 3`

`#define EEDR3_MASK 8`

##### EEDR4 - EEPROM Data Register bit 4

`#define EEDR4_BIT 4`

`#define EEDR4_MASK 16`

##### EEDR5 - EEPROM Data Register bit 5

`#define EEDR5_BIT 5`

`#define EEDR5_MASK 32`

##### EEDR6 - EEPROM Data Register bit 6

`#define EEDR6_BIT 6`

`#define EEDR6_MASK 64`

##### EEDR7 - EEPROM Data Register bit 7

`#define EEDR7_BIT 7`

`#define EEDR7_MASK 128`

### EECR - EEPROM Control Register

`sfrb EECR = $1F;`

##### EERE - EEPROM Read Enable

`#define EERE_BIT 0`

`#define EERE_MASK 1`

The EEPROM Read Enable Signal EERE is the read strobe to the EEPROM. When the correct address is set up in the EEAR register, the EERE bit must be written to a logic one to trigger the EEPROM read. The EEPROM read access takes one instruction, and the requested data is available immediately. When the EEPROM is read, the CPU is halted for four cycles before the next instruction is executed. The user should poll the EEWE bit before starting the read operation. If a write operation is in progress, it is neither possible to read the EEPROM, nor to change the EEAR register. The calibrated oscillator is used to time the EEPROM accesses. Table 1 lists the typical programming time for EEPROM access from the CPU

##### EEWE - EEPROM Write Enable

`#define EEWE_BIT 1`

`#define EEWE_MASK 2`

The EEPROM Write Enable Signal EEWE is the write strobe to the EEPROM. When address and data are correctly set up, the EEWE bit must be set to write the value into the EEPROM. The EEMWE bit must be set when the logical one is written to EEWE, otherwise no EEPROM write takes place. The following procedure should be followed when writing the EEPROM (the order of steps 3 and 4 is not essential): 1. Wait until EEWE becomes zero. 2. Wait until SPMEN in SPMCR becomes zero. 3. Write new EEPROM address to EEAR (optional). 4. Write new EEPROM data to EEDR (optional). 5. Write a logical one to the EEMWE bit while writing a zero to EEWE in EECR. 6. Within four clock cycles after setting EEMWE, write a logical one to EEWE. The EEPROM can not be programmed during a CPU write to the Flash memory. The software must check that the Flash programming is completed before initiating a new EEPROM write. Step 2 is only relevant if the software contains a boot loader allowing the CPU to program the Flash. If the Flash is never being updated by the CPU, step 2 can be omitted. See ?Boot Loader Support - Read While Write self-programming? on page 228 for details about boot programming. Caution: An interrupt between step 5 and step 6 will make the write cycle fail, since the EEPROM Master Write Enable will time-out. If an interrupt routine accessing the EEPROM is interrupting another EEPROM access, the EEAR or EEDR regis-ter will be modified, causing the interrupted EEPROM access to fail. It is recommended to have the global interrupt flag cleared during the 4 last steps to avoid these problems. When the write access time has elapsed, the EEWE bit is cleared by hardware. The user software can poll this bit and wait for a zero before writing the next byte. When EEWE has been set, the CPU is halted for two cycles before the next instruc-tion is executed

##### EEMWE - EEPROM Master Write Enable

`#define EEMWE_BIT 2`

`#define EEMWE_MASK 4`

The EEMWE bit determines whether setting EEWE to one causes the EEPROM to be written. When EEMWE is written to one, writing EEWE to one within 4 clock cycles will write data to the EEPROM at the selected address. If EEMWE is zero, writing EEWE to one will have no effect. When EEMWE has been written to one by software, hardware clears the bit to zero after four clock cycles. See the description of the EEWE bit for an EEPROM write procedure.

##### EERIE - EEPROM Ready Interrupt Enable

`#define EERIE_BIT 3`

`#define EERIE_MASK 8`

EEPROM Ready Interrupt Enable Writing EERIE to one enables the EEPROM Ready Interrupt if the I bit in SREG is set. Writing EERIE to zero disables the interrupt. The EEPROM Ready interrupt generates a constant interrupt when EEWE is cleared.

## SPI

The Serial Peripheral Interface(SPI) allows high-speed synchronous data transfer between the AT90S4414/8515 and peripheral devices or between several AVR devices. The AT90S4414/8515 SPI features include the following: ? Full-duplex, 3-wire Synchronous Data Transfer ? Master or Slave Operation ? LSB First or MSB First Data Transfer ? Four Programmable Bit Rates ? End of Transmission Interrupt Flag ? Write Collision Flag Protection ? Wakeup from Idle Mode (Slave Mode Only)

### SPCR - SPI Control Register

`sfrb SPCR = $2C;`

##### SPR0 - SPI Clock Rate Select 0

`#define SPR0_BIT 0`

`#define SPR0_MASK 1`

These two bits control the SCK rate of the device configured as a master. SPR1 and SPR0 have no effect on the slave.

##### SPR1 - SPI Clock Rate Select 1

`#define SPR1_BIT 1`

`#define SPR1_MASK 2`

These two bits control the SCK rate of the device configured as a master. SPR1 and SPR0 have no effect on the slave.

##### CPHA - Clock Phase

`#define CPHA_BIT 2`

`#define CPHA_MASK 4`

Refer to Figure 36 or Figure 37 for the functionality of this bit.

##### CPOL - Clock polarity

`#define CPOL_BIT 3`

`#define CPOL_MASK 8`

When this bit is set (one), SCK is high when idle. When CPOL is cleared (zero), SCK is low when idle. Refer to Figure 36 and Figure 37 for additional information.

##### MSTR - Master/Slave Select

`#define MSTR_BIT 4`

`#define MSTR_MASK 16`

This bit selects Master SPI mode when set (one), and Slave SPI mode when cleared (zero). If SS is configured as an input and is driven low while MSTR is set, MSTR will be cleared, and SPIF in SPSR will become set. The user will then have to set MSTR to re-enable SPI master mode.

##### DORD - Data Order

`#define DORD_BIT 5`

`#define DORD_MASK 32`

When the DORD bit is set (one), the LSB of the data word is transmitted first. When the DORD bit is cleared (zero), the MSB of the data word is transmitted first.

##### SPE - SPI Enable

`#define SPE_BIT 6`

`#define SPE_MASK 64`

When the SPE bit is set (one), the SPI is enabled. This bit must be set to enable any SPI operations.

##### SPIE - SPI Interrupt Enable

`#define SPIE_BIT 7`

`#define SPIE_MASK 128`

This bit causes the SPI interrupt to be executed if SPIF bit in the SPSR register is set and the global interrupts are enabled.

### SPSR - SPI Status Register

`sfrb SPSR = $2D;`

##### SPI2X - Double SPI Speed Bit

`#define SPI2X_BIT 0`

`#define SPI2X_MASK 1`

When this bit is written logic one the SPI speed (SCK Frequency)will be doubled when the SPI is in master mode .This means that the minimum SCK period will be 2 CPU clock periods.When the SPI is configured as Slave,the SPI is only guaranteed to work at f osc /4orlower. The SPI interface on the ATmega162 is also used for program memory and EEPROM downloading or uploading.

##### WCOL - Write Collision Flag

`#define WCOL_BIT 6`

`#define WCOL_MASK 64`

The WCOL bit is set if the SPI data register (SPDR) is written during a data transfer. The WCOL bit (and the SPIF bit) are cleared (zero) by first reading the SPI Status Register when WCOL is set (one), and then accessing the SPI Data Register.

##### SPIF - SPI Interrupt Flag

`#define SPIF_BIT 7`

`#define SPIF_MASK 128`

When a serial transfer is complete, the SPIF bit is set (one) and an interrupt is generated if SPIE in SPCR is set (one) and global interrupts are enabled. If SS is an input and is driven low when the SPI is in master mode, this will also set the SPIF flag. SPIF is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, the SPIF bit is cleared by first reading the SPI status register when SPIF is set (one), then accessing the SPI Data Register (SPDR).

### SPDR - SPI Data Register

`sfrb SPDR = $2E;`

##### SPDR0 - SPI Data Register bit 0

`#define SPDR0_BIT 0`

`#define SPDR0_MASK 1`

##### SPDR1 - SPI Data Register bit 1

`#define SPDR1_BIT 1`

`#define SPDR1_MASK 2`

##### SPDR2 - SPI Data Register bit 2

`#define SPDR2_BIT 2`

`#define SPDR2_MASK 4`

##### SPDR3 - SPI Data Register bit 3

`#define SPDR3_BIT 3`

`#define SPDR3_MASK 8`

##### SPDR4 - SPI Data Register bit 4

`#define SPDR4_BIT 4`

`#define SPDR4_MASK 16`

##### SPDR5 - SPI Data Register bit 5

`#define SPDR5_BIT 5`

`#define SPDR5_MASK 32`

##### SPDR6 - SPI Data Register bit 6

`#define SPDR6_BIT 6`

`#define SPDR6_MASK 64`

##### SPDR7 - SPI Data Register bit 7

`#define SPDR7_BIT 7`

`#define SPDR7_MASK 128`

## PORTA

### PORTA - Port A Data Register

`sfrb PORTA = $02;`

##### PORTA0 - Port A Data Register bit 0

`#define PORTA0_BIT 0`

`#define PORTA0_MASK 1`

##### PORTA1 - Port A Data Register bit 1

`#define PORTA1_BIT 1`

`#define PORTA1_MASK 2`

##### PORTA2 - Port A Data Register bit 2

`#define PORTA2_BIT 2`

`#define PORTA2_MASK 4`

##### PORTA3 - Port A Data Register bit 3

`#define PORTA3_BIT 3`

`#define PORTA3_MASK 8`

##### PORTA4 - Port A Data Register bit 4

`#define PORTA4_BIT 4`

`#define PORTA4_MASK 16`

##### PORTA5 - Port A Data Register bit 5

`#define PORTA5_BIT 5`

`#define PORTA5_MASK 32`

##### PORTA6 - Port A Data Register bit 6

`#define PORTA6_BIT 6`

`#define PORTA6_MASK 64`

##### PORTA7 - Port A Data Register bit 7

`#define PORTA7_BIT 7`

`#define PORTA7_MASK 128`

### DDRA - Port A Data Direction Register

`sfrb DDRA = $01;`

##### DDA0 - Data Direction Register, Port A, bit 0

`#define DDA0_BIT 0`

`#define DDA0_MASK 1`

##### DDA1 - Data Direction Register, Port A, bit 1

`#define DDA1_BIT 1`

`#define DDA1_MASK 2`

##### DDA2 - Data Direction Register, Port A, bit 2

`#define DDA2_BIT 2`

`#define DDA2_MASK 4`

##### DDA3 - Data Direction Register, Port A, bit 3

`#define DDA3_BIT 3`

`#define DDA3_MASK 8`

##### DDA4 - Data Direction Register, Port A, bit 4

`#define DDA4_BIT 4`

`#define DDA4_MASK 16`

##### DDA5 - Data Direction Register, Port A, bit 5

`#define DDA5_BIT 5`

`#define DDA5_MASK 32`

##### DDA6 - Data Direction Register, Port A, bit 6

`#define DDA6_BIT 6`

`#define DDA6_MASK 64`

##### DDA7 - Data Direction Register, Port A, bit 7

`#define DDA7_BIT 7`

`#define DDA7_MASK 128`

### PINA - Port A Input Pins

`sfrb PINA = $00;`

##### PINA0 - Input Pins, Port A bit 0

`#define PINA0_BIT 0`

`#define PINA0_MASK 1`

##### PINA1 - Input Pins, Port A bit 1

`#define PINA1_BIT 1`

`#define PINA1_MASK 2`

##### PINA2 - Input Pins, Port A bit 2

`#define PINA2_BIT 2`

`#define PINA2_MASK 4`

##### PINA3 - Input Pins, Port A bit 3

`#define PINA3_BIT 3`

`#define PINA3_MASK 8`

##### PINA4 - Input Pins, Port A bit 4

`#define PINA4_BIT 4`

`#define PINA4_MASK 16`

##### PINA5 - Input Pins, Port A bit 5

`#define PINA5_BIT 5`

`#define PINA5_MASK 32`

##### PINA6 - Input Pins, Port A bit 6

`#define PINA6_BIT 6`

`#define PINA6_MASK 64`

##### PINA7 - Input Pins, Port A bit 7

`#define PINA7_BIT 7`

`#define PINA7_MASK 128`

## PORTB

### PORTB - Port B Data Register

`sfrb PORTB = $05;`

##### PORTB0 - Port B Data Register bit 0

`#define PORTB0_BIT 0`

`#define PORTB0_MASK 1`

##### PORTB1 - Port B Data Register bit 1

`#define PORTB1_BIT 1`

`#define PORTB1_MASK 2`

##### PORTB2 - Port B Data Register bit 2

`#define PORTB2_BIT 2`

`#define PORTB2_MASK 4`

##### PORTB3 - Port B Data Register bit 3

`#define PORTB3_BIT 3`

`#define PORTB3_MASK 8`

##### PORTB4 - Port B Data Register bit 4

`#define PORTB4_BIT 4`

`#define PORTB4_MASK 16`

##### PORTB5 - Port B Data Register bit 5

`#define PORTB5_BIT 5`

`#define PORTB5_MASK 32`

##### PORTB6 - Port B Data Register bit 6

`#define PORTB6_BIT 6`

`#define PORTB6_MASK 64`

##### PORTB7 - Port B Data Register bit 7

`#define PORTB7_BIT 7`

`#define PORTB7_MASK 128`

### DDRB - Port B Data Direction Register

`sfrb DDRB = $04;`

##### DDB0 - Port B Data Direction Register bit 0

`#define DDB0_BIT 0`

`#define DDB0_MASK 1`

##### DDB1 - Port B Data Direction Register bit 1

`#define DDB1_BIT 1`

`#define DDB1_MASK 2`

##### DDB2 - Port B Data Direction Register bit 2

`#define DDB2_BIT 2`

`#define DDB2_MASK 4`

##### DDB3 - Port B Data Direction Register bit 3

`#define DDB3_BIT 3`

`#define DDB3_MASK 8`

##### DDB4 - Port B Data Direction Register bit 4

`#define DDB4_BIT 4`

`#define DDB4_MASK 16`

##### DDB5 - Port B Data Direction Register bit 5

`#define DDB5_BIT 5`

`#define DDB5_MASK 32`

##### DDB6 - Port B Data Direction Register bit 6

`#define DDB6_BIT 6`

`#define DDB6_MASK 64`

##### DDB7 - Port B Data Direction Register bit 7

`#define DDB7_BIT 7`

`#define DDB7_MASK 128`

### PINB - Port B Input Pins

`sfrb PINB = $03;`

##### PINB0 - Port B Input Pins bit 0

`#define PINB0_BIT 0`

`#define PINB0_MASK 1`

##### PINB1 - Port B Input Pins bit 1

`#define PINB1_BIT 1`

`#define PINB1_MASK 2`

##### PINB2 - Port B Input Pins bit 2

`#define PINB2_BIT 2`

`#define PINB2_MASK 4`

##### PINB3 - Port B Input Pins bit 3

`#define PINB3_BIT 3`

`#define PINB3_MASK 8`

##### PINB4 - Port B Input Pins bit 4

`#define PINB4_BIT 4`

`#define PINB4_MASK 16`

##### PINB5 - Port B Input Pins bit 5

`#define PINB5_BIT 5`

`#define PINB5_MASK 32`

##### PINB6 - Port B Input Pins bit 6

`#define PINB6_BIT 6`

`#define PINB6_MASK 64`

##### PINB7 - Port B Input Pins bit 7

`#define PINB7_BIT 7`

`#define PINB7_MASK 128`

## PORTC

### PORTC - Port C Data Register

`sfrb PORTC = $08;`

##### PORTC0 - Port C Data Register bit 0

`#define PORTC0_BIT 0`

`#define PORTC0_MASK 1`

##### PORTC1 - Port C Data Register bit 1

`#define PORTC1_BIT 1`

`#define PORTC1_MASK 2`

##### PORTC2 - Port C Data Register bit 2

`#define PORTC2_BIT 2`

`#define PORTC2_MASK 4`

##### PORTC3 - Port C Data Register bit 3

`#define PORTC3_BIT 3`

`#define PORTC3_MASK 8`

##### PORTC4 - Port C Data Register bit 4

`#define PORTC4_BIT 4`

`#define PORTC4_MASK 16`

##### PORTC5 - Port C Data Register bit 5

`#define PORTC5_BIT 5`

`#define PORTC5_MASK 32`

##### PORTC6 - Port C Data Register bit 6

`#define PORTC6_BIT 6`

`#define PORTC6_MASK 64`

##### PORTC7 - Port C Data Register bit 7

`#define PORTC7_BIT 7`

`#define PORTC7_MASK 128`

### DDRC - Port C Data Direction Register

`sfrb DDRC = $07;`

##### DDC0 - Port C Data Direction Register bit 0

`#define DDC0_BIT 0`

`#define DDC0_MASK 1`

##### DDC1 - Port C Data Direction Register bit 1

`#define DDC1_BIT 1`

`#define DDC1_MASK 2`

##### DDC2 - Port C Data Direction Register bit 2

`#define DDC2_BIT 2`

`#define DDC2_MASK 4`

##### DDC3 - Port C Data Direction Register bit 3

`#define DDC3_BIT 3`

`#define DDC3_MASK 8`

##### DDC4 - Port C Data Direction Register bit 4

`#define DDC4_BIT 4`

`#define DDC4_MASK 16`

##### DDC5 - Port C Data Direction Register bit 5

`#define DDC5_BIT 5`

`#define DDC5_MASK 32`

##### DDC6 - Port C Data Direction Register bit 6

`#define DDC6_BIT 6`

`#define DDC6_MASK 64`

##### DDC7 - Port C Data Direction Register bit 7

`#define DDC7_BIT 7`

`#define DDC7_MASK 128`

### PINC - Port C Input Pins

`sfrb PINC = $06;`

##### PINC0 - Port C Input Pins bit 0

`#define PINC0_BIT 0`

`#define PINC0_MASK 1`

##### PINC1 - Port C Input Pins bit 1

`#define PINC1_BIT 1`

`#define PINC1_MASK 2`

##### PINC2 - Port C Input Pins bit 2

`#define PINC2_BIT 2`

`#define PINC2_MASK 4`

##### PINC3 - Port C Input Pins bit 3

`#define PINC3_BIT 3`

`#define PINC3_MASK 8`

##### PINC4 - Port C Input Pins bit 4

`#define PINC4_BIT 4`

`#define PINC4_MASK 16`

##### PINC5 - Port C Input Pins bit 5

`#define PINC5_BIT 5`

`#define PINC5_MASK 32`

##### PINC6 - Port C Input Pins bit 6

`#define PINC6_BIT 6`

`#define PINC6_MASK 64`

##### PINC7 - Port C Input Pins bit 7

`#define PINC7_BIT 7`

`#define PINC7_MASK 128`

## PORTD

### PORTD - Port D Data Register

`sfrb PORTD = $0B;`

##### PORTD0 - Port D Data Register bit 0

`#define PORTD0_BIT 0`

`#define PORTD0_MASK 1`

##### PORTD1 - Port D Data Register bit 1

`#define PORTD1_BIT 1`

`#define PORTD1_MASK 2`

##### PORTD2 - Port D Data Register bit 2

`#define PORTD2_BIT 2`

`#define PORTD2_MASK 4`

##### PORTD3 - Port D Data Register bit 3

`#define PORTD3_BIT 3`

`#define PORTD3_MASK 8`

##### PORTD4 - Port D Data Register bit 4

`#define PORTD4_BIT 4`

`#define PORTD4_MASK 16`

##### PORTD5 - Port D Data Register bit 5

`#define PORTD5_BIT 5`

`#define PORTD5_MASK 32`

##### PORTD6 - Port D Data Register bit 6

`#define PORTD6_BIT 6`

`#define PORTD6_MASK 64`

##### PORTD7 - Port D Data Register bit 7

`#define PORTD7_BIT 7`

`#define PORTD7_MASK 128`

### DDRD - Port D Data Direction Register

`sfrb DDRD = $0A;`

##### DDD0 - Port D Data Direction Register bit 0

`#define DDD0_BIT 0`

`#define DDD0_MASK 1`

##### DDD1 - Port D Data Direction Register bit 1

`#define DDD1_BIT 1`

`#define DDD1_MASK 2`

##### DDD2 - Port D Data Direction Register bit 2

`#define DDD2_BIT 2`

`#define DDD2_MASK 4`

##### DDD3 - Port D Data Direction Register bit 3

`#define DDD3_BIT 3`

`#define DDD3_MASK 8`

##### DDD4 - Port D Data Direction Register bit 4

`#define DDD4_BIT 4`

`#define DDD4_MASK 16`

##### DDD5 - Port D Data Direction Register bit 5

`#define DDD5_BIT 5`

`#define DDD5_MASK 32`

##### DDD6 - Port D Data Direction Register bit 6

`#define DDD6_BIT 6`

`#define DDD6_MASK 64`

##### DDD7 - Port D Data Direction Register bit 7

`#define DDD7_BIT 7`

`#define DDD7_MASK 128`

### PIND - Port D Input Pins

`sfrb PIND = $09;`

##### PIND0 - Port D Input Pins bit 0

`#define PIND0_BIT 0`

`#define PIND0_MASK 1`

##### PIND1 - Port D Input Pins bit 1

`#define PIND1_BIT 1`

`#define PIND1_MASK 2`

##### PIND2 - Port D Input Pins bit 2

`#define PIND2_BIT 2`

`#define PIND2_MASK 4`

##### PIND3 - Port D Input Pins bit 3

`#define PIND3_BIT 3`

`#define PIND3_MASK 8`

##### PIND4 - Port D Input Pins bit 4

`#define PIND4_BIT 4`

`#define PIND4_MASK 16`

##### PIND5 - Port D Input Pins bit 5

`#define PIND5_BIT 5`

`#define PIND5_MASK 32`

##### PIND6 - Port D Input Pins bit 6

`#define PIND6_BIT 6`

`#define PIND6_MASK 64`

##### PIND7 - Port D Input Pins bit 7

`#define PIND7_BIT 7`

`#define PIND7_MASK 128`

## ANALOG COMPARATOR

### ADCSRB - ADC Control and Status Register B

`sfrb ADCSRB = $7B;`

##### ACME - Analog Comparator Multiplexer Enable

`#define ACME_BIT 6`

`#define ACME_MASK 64`

When this bit is written logic one and the ADC is switched off (ADEN in ADCSR is zero), the ADC multiplexer selects the negative input to the Analog Comparator. When this bit is written logic zero, AIN1 is applied to the negative input of the Analog Comparator. For a detailed description of this bit, see ?Analog Comparator Multiplexed Input? on page 186.

### ACSR - Analog Comparator Control And Status Register

`sfrb ACSR = $30;`

##### ACIS0 - Analog Comparator Interrupt Mode Select bit 0

`#define ACIS0_BIT 0`

`#define ACIS0_MASK 1`

These bits determine which comparator events that trigger the Analog Comparator interrupt.

##### ACIS1 - Analog Comparator Interrupt Mode Select bit 1

`#define ACIS1_BIT 1`

`#define ACIS1_MASK 2`

These bits determine which comparator events that trigger the Analog Comparator interrupt.

##### ACIC - Analog Comparator Input Capture Enable

`#define ACIC_BIT 2`

`#define ACIC_MASK 4`

When written logic one, this bit enables the Input Capture function in Timer/Counter1 to be triggered by the analog comparator. The comparator output is in this case directly connected to the Input Capture front-end logic, making the comparator utilize the noise canceler and edge select features of the Timer/Counter1 Input Capture interrupt. When written logic zero, no connection between the analog comparator and the Input Capture function exists. To make the comparator trigger the Timer/Counter1 Input Capture interrupt, the TICIE1 bit in the Timer Interrupt Mask Register (TIMSK) must be set

##### ACIE - Analog Comparator Interrupt Enable

`#define ACIE_BIT 3`

`#define ACIE_MASK 8`

When the ACIE bit is written logic one and the I-bit in the Status Register is set, the analog comparator interrupt is acti-vated. When written logic zero, the interrupt is disabled.

##### ACI - Analog Comparator Interrupt Flag

`#define ACI_BIT 4`

`#define ACI_MASK 16`

This bit is set by hardware when a comparator output event triggers the interrupt mode defined by ACIS1 and ACIS0. The Analog Comparator Interrupt routine is executed if the ACIE bit is set and the I-bit in SREG is set. ACI is cleared by hard-ware when executing the corresponding interrupt handling vector. Alternatively, ACI is cleared by writing a logic one to the flag.

##### ACO - Analog Compare Output

`#define ACO_BIT 5`

`#define ACO_MASK 32`

The output of the analog comparator is synchronized and then directly connected to ACO. The synchronization introduces a delay of 1-2 clock cycles.

##### ACBG - Analog Comparator Bandgap Select

`#define ACBG_BIT 6`

`#define ACBG_MASK 64`

When this bit is set, a fixed bandgap reference voltage replaces the positive input to the Analog Comparator. When this bit is cleared, AIN0 is applied to the positive input of the Analog Comparator. See ?Internal Voltage Reference? on page 42.

##### ACD - Analog Comparator Disable

`#define ACD_BIT 7`

`#define ACD_MASK 128`

When this bit is written logic one, the power to the analog comparator is switched off. This bit can be set at any time to turn off the analog comparator. This will reduce power consumption in active and idle mode. When changing the ACD bit, the Analog Comparator Interrupt must be disabled by clearing the ACIE bit in ACSR. Otherwise an interrupt can occur when the bit is changed.

### DIDR1 - Digital Input Disable Register 1

`sfrb DIDR1 = $7F;`

##### AIN0D - AIN0 Digital Input Disable

`#define AIN0D_BIT 0`

`#define AIN0D_MASK 1`

When this bit is written logic one,the digital input buffer on the AIN1/0 pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the AIN1/0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

##### AIN1D - AIN1 Digital Input Disable

`#define AIN1D_BIT 1`

`#define AIN1D_MASK 2`

When this bit is written logic one,the digital input buffer on the AIN1/0 pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the AIN1/0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

## PORTE

### PORTE - Data Register, Port E

`sfrb PORTE = $0E;`

##### PORTE0

`#define PORTE0_BIT 0`

`#define PORTE0_MASK 1`

##### PORTE1

`#define PORTE1_BIT 1`

`#define PORTE1_MASK 2`

##### PORTE2

`#define PORTE2_BIT 2`

`#define PORTE2_MASK 4`

##### PORTE3

`#define PORTE3_BIT 3`

`#define PORTE3_MASK 8`

##### PORTE4

`#define PORTE4_BIT 4`

`#define PORTE4_MASK 16`

##### PORTE5

`#define PORTE5_BIT 5`

`#define PORTE5_MASK 32`

##### PORTE6

`#define PORTE6_BIT 6`

`#define PORTE6_MASK 64`

##### PORTE7

`#define PORTE7_BIT 7`

`#define PORTE7_MASK 128`

### DDRE - Data Direction Register, Port E

`sfrb DDRE = $0D;`

##### DDE0

`#define DDE0_BIT 0`

`#define DDE0_MASK 1`

##### DDE1

`#define DDE1_BIT 1`

`#define DDE1_MASK 2`

##### DDE2

`#define DDE2_BIT 2`

`#define DDE2_MASK 4`

##### DDE3

`#define DDE3_BIT 3`

`#define DDE3_MASK 8`

##### DDE4

`#define DDE4_BIT 4`

`#define DDE4_MASK 16`

##### DDE5

`#define DDE5_BIT 5`

`#define DDE5_MASK 32`

##### DDE6

`#define DDE6_BIT 6`

`#define DDE6_MASK 64`

##### DDE7

`#define DDE7_BIT 7`

`#define DDE7_MASK 128`

### PINE - Input Pins, Port E

`sfrb PINE = $0C;`

##### PINE0

`#define PINE0_BIT 0`

`#define PINE0_MASK 1`

##### PINE1

`#define PINE1_BIT 1`

`#define PINE1_MASK 2`

##### PINE2

`#define PINE2_BIT 2`

`#define PINE2_MASK 4`

##### PINE3

`#define PINE3_BIT 3`

`#define PINE3_MASK 8`

##### PINE4

`#define PINE4_BIT 4`

`#define PINE4_MASK 16`

##### PINE5

`#define PINE5_BIT 5`

`#define PINE5_MASK 32`

##### PINE6

`#define PINE6_BIT 6`

`#define PINE6_MASK 64`

##### PINE7

`#define PINE7_BIT 7`

`#define PINE7_MASK 128`

## PORTF

### PORTF - Data Register, Port F

`sfrb PORTF = $11;`

##### PORTF0

`#define PORTF0_BIT 0`

`#define PORTF0_MASK 1`

##### PORTF1

`#define PORTF1_BIT 1`

`#define PORTF1_MASK 2`

##### PORTF2

`#define PORTF2_BIT 2`

`#define PORTF2_MASK 4`

##### PORTF3

`#define PORTF3_BIT 3`

`#define PORTF3_MASK 8`

##### PORTF4

`#define PORTF4_BIT 4`

`#define PORTF4_MASK 16`

##### PORTF5

`#define PORTF5_BIT 5`

`#define PORTF5_MASK 32`

##### PORTF6

`#define PORTF6_BIT 6`

`#define PORTF6_MASK 64`

##### PORTF7

`#define PORTF7_BIT 7`

`#define PORTF7_MASK 128`

### DDRF - Data Direction Register, Port F

`sfrb DDRF = $10;`

##### DDF0

`#define DDF0_BIT 0`

`#define DDF0_MASK 1`

##### DDF1

`#define DDF1_BIT 1`

`#define DDF1_MASK 2`

##### DDF2

`#define DDF2_BIT 2`

`#define DDF2_MASK 4`

##### DDF3

`#define DDF3_BIT 3`

`#define DDF3_MASK 8`

##### DDF4

`#define DDF4_BIT 4`

`#define DDF4_MASK 16`

##### DDF5

`#define DDF5_BIT 5`

`#define DDF5_MASK 32`

##### DDF6

`#define DDF6_BIT 6`

`#define DDF6_MASK 64`

##### DDF7

`#define DDF7_BIT 7`

`#define DDF7_MASK 128`

### PINF - Input Pins, Port F

`sfrb PINF = $0F;`

##### PINF0

`#define PINF0_BIT 0`

`#define PINF0_MASK 1`

##### PINF1

`#define PINF1_BIT 1`

`#define PINF1_MASK 2`

##### PINF2

`#define PINF2_BIT 2`

`#define PINF2_MASK 4`

##### PINF3

`#define PINF3_BIT 3`

`#define PINF3_MASK 8`

##### PINF4

`#define PINF4_BIT 4`

`#define PINF4_MASK 16`

##### PINF5

`#define PINF5_BIT 5`

`#define PINF5_MASK 32`

##### PINF6

`#define PINF6_BIT 6`

`#define PINF6_MASK 64`

##### PINF7

`#define PINF7_BIT 7`

`#define PINF7_MASK 128`

## PORTG

### PORTG - Port G Data Register

`sfrb PORTG = $14;`

##### PORTG0

`#define PORTG0_BIT 0`

`#define PORTG0_MASK 1`

##### PORTG1

`#define PORTG1_BIT 1`

`#define PORTG1_MASK 2`

##### PORTG2

`#define PORTG2_BIT 2`

`#define PORTG2_MASK 4`

##### PORTG3

`#define PORTG3_BIT 3`

`#define PORTG3_MASK 8`

##### PORTG4

`#define PORTG4_BIT 4`

`#define PORTG4_MASK 16`

### DDRG - Port G Data Direction Register

`sfrb DDRG = $13;`

##### DDG0

`#define DDG0_BIT 0`

`#define DDG0_MASK 1`

##### DDG1

`#define DDG1_BIT 1`

`#define DDG1_MASK 2`

##### DDG2

`#define DDG2_BIT 2`

`#define DDG2_MASK 4`

##### DDG3

`#define DDG3_BIT 3`

`#define DDG3_MASK 8`

##### DDG4

`#define DDG4_BIT 4`

`#define DDG4_MASK 16`

### PING - Port G Input Pins

`sfrb PING = $12;`

##### PING0

`#define PING0_BIT 0`

`#define PING0_MASK 1`

##### PING1

`#define PING1_BIT 1`

`#define PING1_MASK 2`

##### PING2

`#define PING2_BIT 2`

`#define PING2_MASK 4`

##### PING3

`#define PING3_BIT 3`

`#define PING3_MASK 8`

##### PING4

`#define PING4_BIT 4`

`#define PING4_MASK 16`

##### PING5

`#define PING5_BIT 5`

`#define PING5_MASK 32`

## JTAG

JTAG Features: JTAG (IEEE std. 1149.1 compliant) Interface. Boundary-Scan Capabilities According to the IEEE std. 1149.1 (JTAG) Standard. Debugger Access to: ? All Internal Peripheral Units ? Internal and External RAM ? The Internal Register File ?Program Counter ? EEPROM and Flash Memories. Extensive On-Chip Debug Support for Break Conditions, Including: ?AVR Break Instruction ? Break on Change of Program Memory Flow ?Single Step Break ?Program Memory Breakpoints on Single Address or Address Range ? Data Memory Breakpoints on Single Address or Address Range. Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG Interface. On-Chip Debugging Supported by AVR Stu

### OCDR - On-Chip Debug Related Register in I/O Memory

`sfrb OCDR = $31;`

##### OCDR0 - On-Chip Debug Register Bit 0

`#define OCDR0_BIT 0`

`#define OCDR0_MASK 1`

##### OCDR1 - On-Chip Debug Register Bit 1

`#define OCDR1_BIT 1`

`#define OCDR1_MASK 2`

##### OCDR2 - On-Chip Debug Register Bit 2

`#define OCDR2_BIT 2`

`#define OCDR2_MASK 4`

##### OCDR3 - On-Chip Debug Register Bit 3

`#define OCDR3_BIT 3`

`#define OCDR3_MASK 8`

##### OCDR4 - On-Chip Debug Register Bit 4

`#define OCDR4_BIT 4`

`#define OCDR4_MASK 16`

##### OCDR5 - On-Chip Debug Register Bit 5

`#define OCDR5_BIT 5`

`#define OCDR5_MASK 32`

##### OCDR6 - On-Chip Debug Register Bit 6

`#define OCDR6_BIT 6`

`#define OCDR6_MASK 64`

##### OCDR7 - On-Chip Debug Register Bit 7

`#define OCDR7_BIT 7`

`#define OCDR7_MASK 128`

### MCUCR - MCU Control Register

`sfrb MCUCR = $35;`

##### JTD - JTAG Interface Disable

`#define JTD_BIT 7`

`#define JTD_MASK 128`

When this bit is written to zero, the JTAG interface is enabled if the JTAGEN fuse is programmed. If this bit is written to one, the JTAG interface is disabled. In order to avoid unintentional disabling or enabling of the JTAG interface, a timed sequence must be followed: The application software must write this to the desired value twice within four cycles to change the bit.

### MCUSR - MCU Status Register

`sfrb MCUSR = $34;`

##### JTRF - JTAG Reset Flag

`#define JTRF_BIT 4`

`#define JTRF_MASK 16`

This bit is set if a reset is being caused by a logic one in the JTAG Reset Register selected by the JTAG instruction AVR_RESET.This bit is reset by a Power-on reset,or by writing a logic zero to the flag.

## EXTERNAL INTERRUPT

The external interrupts are triggered by the INT7:0 pins. Observe that, if enabled, the interrupts will trigger even if the INT7:0 pins are configured as outputs. This feature provides a way of generating a software interrupt. The external inter-rupts can be triggered by a falling or rising edge or a low level. This is set up as indicated in the specification for the Exter-nal Interrupt Control Registers - EICRA (INT3:0) and EICRB (INT7:4). When the external interrupt is enabled and is configured as level triggered, the interrupt will trigger as long as the pin is held low. Note that recognition of falling or rising edge interrupts on INT7:4 requires the presence of an I/O clock, described in ?Clock Systems and their Distribution? on page 29. Low level interrupts and the edge interrupt on INT3:0 are detected asynchronously. This implies that these inter-rupts can be used for waking the part also from sleep modes other than Idle mode. The I/O clock is halted in all sleep modes except Idle mode. Note that if a level triggered interrupt is used for wake-up from Power Down Mode, the changed level must be held for some time to wake up the MCU. This makes the MCU less sensitive to noise. The changed level is sampled twice by the watchdog oscillator clock. The period of the watchdog oscillator is 1 µs (nominal) at 5.0V and 25°C. The frequency of the watchdog oscillator is voltage dependent as shown in the Electrical Characteristics section. The MCU will wake up if the input has the required level during this sampling or if it is held until the end of the start-up time. The start-up time is defined by the SUT fuses as described in ?Clock Systems and their Distribution? on page 29. If the level is sampled twice by the watchdog oscillator clock but disappears before the end of the start-up time, the MCU will still wake up, but no interrupt will be generated. The required level must be held long enough for the MCU to complete the wake up to trigger the level interrup

### EICRA - External Interrupt Control Register

`sfrb EICRA = $69;`

##### ISC00 - External Interrupt Sense Control 0 Bit 0

`#define ISC00_BIT 0`

`#define ISC00_MASK 1`

The External Interrupt 0 is activated by the external pin INT0 if the SREG I-flag and the corresponding interrupt mask are set.The value on the INT0 pin is sampled before detecting edges.If edge or toggle interrupt is selected,pulses that last longer than one clock period will generate an interrupt.Shorter pulses are not guaranteed to generate an interrupt.If low level interrupt is selected,the lowlevel must be held until the completion of the currently executing instruction to generate an interrupt.

##### ISC01 - External Interrupt Sense Control 0 Bit 1

`#define ISC01_BIT 1`

`#define ISC01_MASK 2`

The External Interrupt 0 is activated by the external pin INT0 if the SREG I-flag and the corresponding interrupt mask are set.The value on the INT0 pin is sampled before detecting edges.If edge or toggle interrupt is selected,pulses that last longer than one clock period will generate an interrupt.Shorter pulses are not guaranteed to generate an interrupt.If low level interrupt is selected,the lowlevel must be held until the completion of the currently executing instruction to generate an interrupt.

### EIMSK - External Interrupt Mask Register

`sfrb EIMSK = $1D;`

##### INT0 - External Interrupt Request 0 Enable

`#define INT0_BIT 0`

`#define INT0_MASK 1`

When the INT0 bit is set (one)and the I-bit in the Status Register (SREG)is set (one),the external pin interrupt is enabled. The Interrupt Sense Control0 bits 1/0 (ISC01 and ISC00)in the External Interrupt Control Register A (EICRA)define whether the external interrupt is activated on rising and/or falling edge of the INT0 pin or level sensed.Activity on the pin will cause an interrupt request even if INT0 is configured as an output.The corresponding interrupt of External Interrupt Request 0 is executed from the INT0 interrupt vector.

##### PCIE0 - Pin Change Interrupt Enable 0

`#define PCIE0_BIT 6`

`#define PCIE0_MASK 64`

When the PCIE0 bit is set (one)and the I-bit in the Status Register (SREG)is set (one),pin change interrupt 0 is enabled. Any change on any enabled PCINT7..0 pin will cause an interrupt.The corresponding interrupt of Pin Change Interrupt Request is executed from the PCI0 interrupt vector.PCINT7..0 pins are enabled individually by the PCMSK0 register.

##### PCIE1 - Pin Change Interrupt Enable 1

`#define PCIE1_BIT 7`

`#define PCIE1_MASK 128`

When the PCIE1 bit is set (one)and the I-bit in the Status Register (SREG)is set (one),pin change interrupt 1 is enabled. Any change on any enabled PCINT15..8 pin will cause an interrupt.The corresponding interrupt of Pin Change Interrupt Request is executed from the PCI1 interrupt vector.PCINT15..8 pins are enabled individually by the PCMSK1 register.

### EIFR - External Interrupt Flag Register

`sfrb EIFR = $1C;`

##### INTF0 - External Interrupt Flag 0

`#define INTF0_BIT 0`

`#define INTF0_MASK 1`

When an edge or logic change on the INT0 pin triggers an interrupt request,INTF0 becomes set (one).If the I-bit in SREG and the INT0 bit in EIMSK are set (one),the MCU will jump to the corresponding interrupt vector.The flag is cleared when the interrupt routine is executed.Alternatively,the flag can be cleared by writing a logical one to it.This flag is always cleared when INT0 is configured as a level interrupt.

##### PCIF0 - Pin Change Interrupt Flag 0

`#define PCIF0_BIT 6`

`#define PCIF0_MASK 64`

When a logic change on any PCINT7..0 pin triggers an interrupt request,PCIF0 becomes set (one).If the I-bit in SREG and the PCIE0 bit in EIMSK are set (one),the MCU will jump to the corresponding interrupt vector.The flag is cleared when the interrupt routine is executed.Alternatively,the flag can be cleared by writing a logical one to it.

##### PCIF1 - Pin Change Interrupt Flag 1

`#define PCIF1_BIT 7`

`#define PCIF1_MASK 128`

When a logic change on any PCINT15..8 pin triggers an interrupt request,PCIF1 becomes set (one).If the I-bit in SREG and the PCIE1 bit in EIMSK are set (one),the MCU will jump to the corresponding interrupt vector.The flag is cleared when the interrupt routine is executed.Alternatively,the flag can be cleared by writing a logical one to it.

### PCMSK1 - Pin Change Mask Register 1

`sfrb PCMSK1 = $6C;`

##### PCINT8 - Pin Change Enable Mask 8

`#define PCINT8_BIT 0`

`#define PCINT8_MASK 1`

##### PCINT9 - Pin Change Enable Mask 9

`#define PCINT9_BIT 1`

`#define PCINT9_MASK 2`

##### PCINT10 - Pin Change Enable Mask 10

`#define PCINT10_BIT 2`

`#define PCINT10_MASK 4`

##### PCINT11 - Pin Change Enable Mask 11

`#define PCINT11_BIT 3`

`#define PCINT11_MASK 8`

##### PCINT12 - Pin Change Enable Mask 12

`#define PCINT12_BIT 4`

`#define PCINT12_MASK 16`

##### PCINT13 - Pin Change Enable Mask 13

`#define PCINT13_BIT 5`

`#define PCINT13_MASK 32`

##### PCINT14 - Pin Change Enable Mask 14

`#define PCINT14_BIT 6`

`#define PCINT14_MASK 64`

##### PCINT15 - Pin Change Enable Mask 15

`#define PCINT15_BIT 7`

`#define PCINT15_MASK 128`

### PCMSK0 - Pin Change Mask Register 0

`sfrb PCMSK0 = $6B;`

##### PCINT0 - Pin Change Enable Mask 0

`#define PCINT0_BIT 0`

`#define PCINT0_MASK 1`

##### PCINT1 - Pin Change Enable Mask 1

`#define PCINT1_BIT 1`

`#define PCINT1_MASK 2`

##### PCINT2 - Pin Change Enable Mask 2

`#define PCINT2_BIT 2`

`#define PCINT2_MASK 4`

##### PCINT3 - Pin Change Enable Mask 3

`#define PCINT3_BIT 3`

`#define PCINT3_MASK 8`

##### PCINT4 - Pin Change Enable Mask 4

`#define PCINT4_BIT 4`

`#define PCINT4_MASK 16`

##### PCINT5 - Pin Change Enable Mask 5

`#define PCINT5_BIT 5`

`#define PCINT5_MASK 32`

##### PCINT6 - Pin Change Enable Mask 6

`#define PCINT6_BIT 6`

`#define PCINT6_MASK 64`

##### PCINT7 - Pin Change Enable Mask 7

`#define PCINT7_BIT 7`

`#define PCINT7_MASK 128`

## USI

Universal Serial Interface

### USIDR - USI Data Register

`sfrb USIDR = $BA;`

##### USIDR0 - USI Data Register bit 0

`#define USIDR0_BIT 0`

`#define USIDR0_MASK 1`

##### USIDR1 - USI Data Register bit 1

`#define USIDR1_BIT 1`

`#define USIDR1_MASK 2`

##### USIDR2 - USI Data Register bit 2

`#define USIDR2_BIT 2`

`#define USIDR2_MASK 4`

##### USIDR3 - USI Data Register bit 3

`#define USIDR3_BIT 3`

`#define USIDR3_MASK 8`

##### USIDR4 - USI Data Register bit 4

`#define USIDR4_BIT 4`

`#define USIDR4_MASK 16`

##### USIDR5 - USI Data Register bit 5

`#define USIDR5_BIT 5`

`#define USIDR5_MASK 32`

##### USIDR6 - USI Data Register bit 6

`#define USIDR6_BIT 6`

`#define USIDR6_MASK 64`

##### USIDR7 - USI Data Register bit 7

`#define USIDR7_BIT 7`

`#define USIDR7_MASK 128`

### USISR - USI Status Register

`sfrb USISR = $B9;`

##### USICNT0 - USI Counter Value Bit 0

`#define USICNT0_BIT 0`

`#define USICNT0_MASK 1`

##### USICNT1 - USI Counter Value Bit 1

`#define USICNT1_BIT 1`

`#define USICNT1_MASK 2`

##### USICNT2 - USI Counter Value Bit 2

`#define USICNT2_BIT 2`

`#define USICNT2_MASK 4`

##### USICNT3 - USI Counter Value Bit 3

`#define USICNT3_BIT 3`

`#define USICNT3_MASK 8`

##### USIDC - Data Output Collision

`#define USIDC_BIT 4`

`#define USIDC_MASK 16`

##### USIPF - Stop Condition Flag

`#define USIPF_BIT 5`

`#define USIPF_MASK 32`

##### USIOIF - Counter Overflow Interrupt Flag

`#define USIOIF_BIT 6`

`#define USIOIF_MASK 64`

##### USISIF - Start Condition Interrupt Flag

`#define USISIF_BIT 7`

`#define USISIF_MASK 128`

### USICR - USI Control Register

`sfrb USICR = $B8;`

##### USITC - Toggle Clock Port Pin

`#define USITC_BIT 0`

`#define USITC_MASK 1`

##### USICLK - Clock Strobe

`#define USICLK_BIT 1`

`#define USICLK_MASK 2`

##### USICS0 - USI Clock Source Select Bit 0

`#define USICS0_BIT 2`

`#define USICS0_MASK 4`

##### USICS1 - USI Clock Source Select Bit 1

`#define USICS1_BIT 3`

`#define USICS1_MASK 8`

##### USIWM0 - USI Wire Mode Bit 0

`#define USIWM0_BIT 4`

`#define USIWM0_MASK 16`

##### USIWM1 - USI Wire Mode Bit 1

`#define USIWM1_BIT 5`

`#define USIWM1_MASK 32`

##### USIOIE - Counter Overflow Interrupt Enable

`#define USIOIE_BIT 6`

`#define USIOIE_MASK 64`

##### USISIE - Start Condition Interrupt Enable

`#define USISIE_BIT 7`

`#define USISIE_MASK 128`

## AD CONVERTER

AD Converter Feature list: 10-bit Resolution. 0.5 LSB Integral Non-Linearity. +-2 LSB Absolute Accuracy. TBD - 260 µs Conversion Time. Up to TBD kSPS at maximum resolution. 8 Multiplexed Single Ended Input Channels. 7 Differential input channels (TQFP package only). 2 Differential input channels with optional gain of 10x and 200x (TQFP package only). Optional left adjustment for ADC result readout. 0 - VCC ADC Input Voltage Range. Selectable 2.56 V ADC reference voltage. Free Running or Single Conversion Mode. Interrupt on ADC Conversion Complete. Sleep Mode Nois

### ADMUX - The ADC multiplexer Selection Register

`sfrb ADMUX = $7C;`

##### MUX0 - Analog Channel and Gain Selection Bits

`#define MUX0_BIT 0`

`#define MUX0_MASK 1`

The value of these bits selects which combination of analog inputs are connected to the ADC. These bits also select the gain for the differential channels. See Table 92 for details. If these bits are changed during a conversion, the change will not go in effect until this conversion is complete (ADIF in ADCSR is set).

##### MUX1 - Analog Channel and Gain Selection Bits

`#define MUX1_BIT 1`

`#define MUX1_MASK 2`

The value of these bits selects which combination of analog inputs are connected to the ADC. These bits also select the gain for the differential channels. See Table 92 for details. If these bits are changed during a conversion, the change will not go in effect until this conversion is complete (ADIF in ADCSR is set).

##### MUX2 - Analog Channel and Gain Selection Bits

`#define MUX2_BIT 2`

`#define MUX2_MASK 4`

The value of these bits selects which combination of analog inputs are connected to the ADC. These bits also select the gain for the differential channels. See Table 92 for details. If these bits are changed during a conversion, the change will not go in effect until this conversion is complete (ADIF in ADCSR is set).

##### MUX3 - Analog Channel and Gain Selection Bits

`#define MUX3_BIT 3`

`#define MUX3_MASK 8`

The value of these bits selects which combination of analog inputs are connected to the ADC. These bits also select the gain for the differential channels. See Table 92 for details. If these bits are changed during a conversion, the change will not go in effect until this conversion is complete (ADIF in ADCSR is set).

##### MUX4 - Analog Channel and Gain Selection Bits

`#define MUX4_BIT 4`

`#define MUX4_MASK 16`

The value of these bits selects which combination of analog inputs are connected to the ADC. These bits also select the gain for the differential channels. See Table 92 for details. If these bits are changed during a conversion, the change will not go in effect until this conversion is complete (ADIF in ADCSR is set).

##### ADLAR - Left Adjust Result

`#define ADLAR_BIT 5`

`#define ADLAR_MASK 32`

The ADLAR bit affects the presentation of the ADC conversion result in the ADC data register. If ADLAR is cleared, the result is right adjusted. If ADLAR is set, the result is left adjusted. Changing the ADLAR bit will affect the ADC data register immediately, regardless of any ongoing conversions. For a complete description of this bit, see ?The ADC Data Register -ADCL and ADCH? on page 198.

##### REFS0 - Reference Selection Bit 0

`#define REFS0_BIT 6`

`#define REFS0_MASK 64`

These bits select the voltage reference for the ADC, as shown in Table 91. If these bits are changed during a conversion, the change will not go in effect until this conversion is complete (ADIF in ADCSR is set). If differential channels are used, the selected reference should not be closer to AV CC than indicated in Table 94 on page 200. The internal voltage reference options may not be used if an external reference voltage is being applied to the AREF pin.

##### REFS1 - Reference Selection Bit 1

`#define REFS1_BIT 7`

`#define REFS1_MASK 128`

These bits select the voltage reference for the ADC, as shown in Table 91. If these bits are changed during a conversion, the change will not go in effect until this conversion is complete (ADIF in ADCSR is set). If differential channels are used, the selected reference should not be closer to AV CC than indicated in Table 94 on page 200. The internal voltage reference options may not be used if an external reference voltage is being applied to the AREF pin.

### ADCSRA - The ADC Control and Status register

`sfrb ADCSRA = $7A;`

##### ADPS0 - ADC Prescaler Select Bits

`#define ADPS0_BIT 0`

`#define ADPS0_MASK 1`

These bits determine the division factor between the XTAL frequency and the input clock to the ADC.

##### ADPS1 - ADC Prescaler Select Bits

`#define ADPS1_BIT 1`

`#define ADPS1_MASK 2`

These bits determine the division factor between the XTAL frequency and the input clock to the ADC.

##### ADPS2 - ADC Prescaler Select Bits

`#define ADPS2_BIT 2`

`#define ADPS2_MASK 4`

These bits determine the division factor between the XTAL frequency and the input clock to the ADC.

##### ADIE - ADC Interrupt Enable

`#define ADIE_BIT 3`

`#define ADIE_MASK 8`

When this bit is set (one) and the I-bit in SREG is set (one), the ADC Conversion Complete Interrupt is activated.

##### ADIF - ADC Interrupt Flag

`#define ADIF_BIT 4`

`#define ADIF_MASK 16`

This bit is set (one) when an ADC conversion completes and the data registers are updated. The ADC Conversion Complete Interrupt is executed if the ADIE bit and the I-bit in SREG are set (one). ADIF is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ADIF is cleared by writing a logical one to the flag. Beware that if doing a read-modify-write on ADCSR, a pending interrupt can be disabled. This also applies if the SBI and CBI instructions are used.

##### ADATE - ADC Auto Trigger Enable

`#define ADATE_BIT 5`

`#define ADATE_MASK 32`

When this bit is written to one,Auto Triggering of the ADC is enabled.The ADC will start a conversion on a positive edge of the selected trigger signal.The trigger source is selected by setting the ADC Trigger Select bits,ADTS in ADCSRB.

##### ADSC - ADC Start Conversion

`#define ADSC_BIT 6`

`#define ADSC_MASK 64`

In Single Conversion Mode, a logical ?1? must be written to this bit to start each conversion. In Free Running Mode, a logical ?1? must be written to this bit to start the first conversion. The first time ADSC has been written after the ADC has been enabled, or if ADSC is written at the same time as the ADC is enabled, an extended conversion will result. This extended conversion performs initialization of the ADC. ADSC will read as one as long as a conversion is in progress. When the conversion is complete, it returns to zero. When a dummy conversion precedes a real conversion, ADSC will stay high until the real conversion completes. Writing a 0 to this bit has no effect

##### ADEN - ADC Enable

`#define ADEN_BIT 7`

`#define ADEN_MASK 128`

Writing a logical ?1? to this bit enables the ADC. By clearing this bit to zero, the ADC is turned off. Turning the ADC off while a conversion is in progress, will terminate this conversion.

### ADCH - ADC Data Register High Byte

`sfrb ADCH = $79;`

##### ADCH0 - ADC Data Register High Byte Bit 0

`#define ADCH0_BIT 0`

`#define ADCH0_MASK 1`

##### ADCH1 - ADC Data Register High Byte Bit 1

`#define ADCH1_BIT 1`

`#define ADCH1_MASK 2`

##### ADCH2 - ADC Data Register High Byte Bit 2

`#define ADCH2_BIT 2`

`#define ADCH2_MASK 4`

##### ADCH3 - ADC Data Register High Byte Bit 3

`#define ADCH3_BIT 3`

`#define ADCH3_MASK 8`

##### ADCH4 - ADC Data Register High Byte Bit 4

`#define ADCH4_BIT 4`

`#define ADCH4_MASK 16`

##### ADCH5 - ADC Data Register High Byte Bit 5

`#define ADCH5_BIT 5`

`#define ADCH5_MASK 32`

##### ADCH6 - ADC Data Register High Byte Bit 6

`#define ADCH6_BIT 6`

`#define ADCH6_MASK 64`

##### ADCH7 - ADC Data Register High Byte Bit 7

`#define ADCH7_BIT 7`

`#define ADCH7_MASK 128`

### ADCL - ADC Data Register Low Byte

`sfrb ADCL = $78;`

##### ADCL0 - ADC Data Register Low Byte Bit 0

`#define ADCL0_BIT 0`

`#define ADCL0_MASK 1`

##### ADCL1 - ADC Data Register Low Byte Bit 1

`#define ADCL1_BIT 1`

`#define ADCL1_MASK 2`

##### ADCL2 - ADC Data Register Low Byte Bit 2

`#define ADCL2_BIT 2`

`#define ADCL2_MASK 4`

##### ADCL3 - ADC Data Register Low Byte Bit 3

`#define ADCL3_BIT 3`

`#define ADCL3_MASK 8`

##### ADCL4 - ADC Data Register Low Byte Bit 4

`#define ADCL4_BIT 4`

`#define ADCL4_MASK 16`

##### ADCL5 - ADC Data Register Low Byte Bit 5

`#define ADCL5_BIT 5`

`#define ADCL5_MASK 32`

##### ADCL6 - ADC Data Register Low Byte Bit 6

`#define ADCL6_BIT 6`

`#define ADCL6_MASK 64`

##### ADCL7 - ADC Data Register Low Byte Bit 7

`#define ADCL7_BIT 7`

`#define ADCL7_MASK 128`

### ADCSRB - ADC Control and Status Register B

`sfrb ADCSRB = $7B;`

##### ADTS0 - ADC Auto Trigger Source 0

`#define ADTS0_BIT 0`

`#define ADTS0_MASK 1`

If ADATE in ADCSRA is written to one,the value of these bits selects which source will trigger an ADC conversion.If ADATE is cleared,the ADTS2:0 settings will have no effect.A conversion will be triggered by the rising edge of the selected interrupt flag.Note that switching from a trigger source that is cleared to a trigger source that is set,will generate a positive edge on the trigger signal.If ADEN in ADCSRA is set,this will start a conversion.Switching to Free Running Mode (ADTS [2:0 ]=0)will not cause a trigger event,even if the ADC Interrupt Flag is set .

##### ADTS1 - ADC Auto Trigger Source 1

`#define ADTS1_BIT 1`

`#define ADTS1_MASK 2`

If ADATE in ADCSRA is written to one,the value of these bits selects which source will trigger an ADC conversion.If ADATE is cleared,the ADTS2:0 settings will have no effect.A conversion will be triggered by the rising edge of the selected interrupt flag.Note that switching from a trigger source that is cleared to a trigger source that is set,will generate a positive edge on the trigger signal.If ADEN in ADCSRA is set,this will start a conversion.Switching to Free Running Mode (ADTS [2:0 ]=0)will not cause a trigger event,even if the ADC Interrupt Flag is set .

##### ADTS2 - ADC Auto Trigger Source 2

`#define ADTS2_BIT 2`

`#define ADTS2_MASK 4`

If ADATE in ADCSRA is written to one,the value of these bits selects which source will trigger an ADC conversion.If ADATE is cleared,the ADTS2:0 settings will have no effect.A conversion will be triggered by the rising edge of the selected interrupt flag.Note that switching from a trigger source that is cleared to a trigger source that is set,will generate a positive edge on the trigger signal.If ADEN in ADCSRA is set,this will start a conversion.Switching to Free Running Mode (ADTS [2:0 ]=0)will not cause a trigger event,even if the ADC Interrupt Flag is set .

### DIDR0 - Digital Input Disable Register 0

`sfrb DIDR0 = $7E;`

##### ADC0D - ADC0 Digital input Disable

`#define ADC0D_BIT 0`

`#define ADC0D_MASK 1`

When this bit is written logic one,the digital input buffer on the corresponding ADC pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the ADC7..0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

##### ADC1D - ADC1 Digital input Disable

`#define ADC1D_BIT 1`

`#define ADC1D_MASK 2`

When this bit is written logic one,the digital input buffer on the corresponding ADC pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the ADC7..0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

##### ADC2D - ADC2 Digital input Disable

`#define ADC2D_BIT 2`

`#define ADC2D_MASK 4`

When this bit is written logic one,the digital input buffer on the corresponding ADC pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the ADC7..0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

##### ADC3D - ADC3 Digital input Disable

`#define ADC3D_BIT 3`

`#define ADC3D_MASK 8`

When this bit is written logic one,the digital input buffer on the corresponding ADC pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the ADC7..0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

##### ADC4D - ADC4 Digital input Disable

`#define ADC4D_BIT 4`

`#define ADC4D_MASK 16`

When this bit is written logic one,the digital input buffer on the corresponding ADC pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the ADC7..0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

##### ADC5D - ADC5 Digital input Disable

`#define ADC5D_BIT 5`

`#define ADC5D_MASK 32`

When this bit is written logic one,the digital input buffer on the corresponding ADC pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the ADC7..0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

##### ADC6D - ADC6 Digital input Disable

`#define ADC6D_BIT 6`

`#define ADC6D_MASK 64`

When this bit is written logic one,the digital input buffer on the corresponding ADC pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the ADC7..0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

##### ADC7D - ADC7 Digital input Disable

`#define ADC7D_BIT 7`

`#define ADC7D_MASK 128`

When this bit is written logic one,the digital input buffer on the corresponding ADC pin is disabled.The corresponding PIN register bit will always read as zero when this bit is set.When an analog signal is applied to the ADC7..0 pin and the digital input from this pin is not needed,this bit should be written logic one to reduce power consumption in the digital input buffer.

## BOOT LOAD

The Boot Loader Support provides a real Read While Write self-programming mechanism for downloading and uploading program code by the MCU itself. This feature allows flexible application software updates controlled by the MCU using a Flash-resident Boot Loader program. The Boot Loader program can use any available data interface and associated proto-col to read code and write (program) that code into the Flash memory, or read the code from the program memory. The program code within the Boot Loader section has the capability to write into the entire Flash, including the Boot Loader Memory. The Boot Loader can thus even modify itself, and it can also erase itself from the code if the feature is not needed anymore. The size of the Boot Loader Memory is configurable with fuses and the Boot Loader has two separate sets of Boot Lock Bits which can be set independently. This gives the user a unique flexibility to select different levels of protection. Boot Loader Features: Read While Write self-programming. Flexibl Boot Memory size. High security (separate Boot Lock bits for a flexible protection). Separate fuse to select reset vector Optimized page (1) size. Code efficient algorithm Efficient read-modify-write suppor

### SPMCSR - Store Program Memory Control Register

`sfrb SPMCSR = $37;`

##### SPMEN - Store Program Memory Enable

`#define SPMEN_BIT 0`

`#define SPMEN_MASK 1`

This bit enables the SPM instruction for the next four clock cycles. If written to one together with either RWWSRE, BLB-SET, PGWRT or PGERS, the following SPM instruction will have a special meaning, see description above. If only SPMEN is written, the following SPM instruction will store the value in R1:R0 in the temporary page buffer addressed by the Z pointer. The LSB of the Z pointer is ignored. The SPMEN bit will auto-clear upon completion of an SPM instruction, or if no SPM instruction is executed within four clock cycles. During page erase and page write, the SPMEN bit remain high until the operation is completed. Writing any other combination than ?10001?, "01001", "00101", "00011" or "00001" in the lower five bits will have no effec

##### PGERS - Page Erase

`#define PGERS_BIT 1`

`#define PGERS_MASK 2`

If this bit is written to one at the same time as SPMEN, the next SPM instruction within four clock cycles executes page erase. The page address is taken from the high part of the Z pointer. The data in R1 and R0 are ignored. The PGERS bit will auto-clear upon completion of a page erase, or if no SPM instruction is executed within four clock cycles. The CPU is halted during the entire page write operation if the NRWW section is addressed.

##### PGWRT - Page Write

`#define PGWRT_BIT 2`

`#define PGWRT_MASK 4`

If this bit is written to one at the same time as SPMEN, the next SPM instruction within four clock cycles executes page write, with the data stored in the temporary buffer. The page address is taken from the high part of the Z pointer. The data in R1 and R0 are ignored. The PGWRT bit will auto-clear upon completion of a page write, or if no SPM instruction is exe-cuted within four clock cycles. The CPU is halted during the entire page write operation if the NRWW section is addressed.

##### BLBSET - Boot Lock Bit Set

`#define BLBSET_BIT 3`

`#define BLBSET_MASK 8`

If this bit is written to one at the same time as SPMEN, the next SPM instruction within four clock cycles sets Boot Lock bits, according to the data in R0. The data in R1 and the address in the Z pointer are ignored. The BLBSET bit will automatically be cleared upon completion of the lock bit set, or if no SPM instruction is executed within four clock cycles. An LPM instruction within three cycles after BLBSET and SPMEN are set in the SPMCR register, will read either the Lock-bits or the Fuse bits (depending on Z0 in the Z pointer) into the destination register. See ?Reading the Fuse and Lock Bits from Software? on page 235 for details

##### RWWSRE - Read While Write section read enable

`#define RWWSRE_BIT 4`

`#define RWWSRE_MASK 16`

When programming (page erase or page write) to the RWW section, the RWW section is blocked for reading (the RWWSB will be set by hardware). To re-enable the RWW section, the user software must wait until the programming is completed (SPMEN will be cleared). Then, if the RWWSRE bit is written to one at the same time as SPMEN, the next SPM instruction within four clock cycles re-enables the RWW section. The RWW section cannot be re-enabled while Flash is busy with a page erase or a page write (SPMEN is set). If the RWWSRE bit is written while the Flash is being loaded, the Flash load operation will abort and the data loaded will be lo

##### RWWSB - Read While Write Section Busy

`#define RWWSB_BIT 6`

`#define RWWSB_MASK 64`

When a self-programming (page erase or page write) operation to the RWW section is initiated, the RWWSB will be set (one) by hardware. When the RWWSB bit is set, the RWW section cannot be accessed. The RWWSB bit will be cleared if the RWWSRE bit is written to one after a self-programming operation is completed. Alternatively the RWWSB bit will auto-matically be cleared if a page load operation is initiated.

##### SPMIE - SPM Interrupt Enable

`#define SPMIE_BIT 7`

`#define SPMIE_MASK 128`

When the SPMIE bit is written to one, and the I-bit in the Status Register is set (one), the SPM ready interrupt will be enabled. The SPM ready Interrupt will be executed as long as the SPMEN bit in the SPMCR register is cleared.

## USART0

The Universal Synchronous and Asynchronous serial Receiver and Transmitter (USART) is a highly flexible serial communication device. The main features are: ? Full Duplex Operation (Independent Serial Receive and Transmit Registers) ? Asynchronous or Synchronous Operation ? Master or Slave Clocked Synchronous Operation ? High Resolution Baud Rate Generator ? Supports Serial Frames with 5, 6, 7, 8 or 9 Data Bits and 1 or 2 Stop Bits ? Odd or Even Parity Generation and Parity Check Supported by Hardware ? Data OverRun Detection ? Framing Error Detection ? Noise Filtering Includes False Start Bit Detection and Digital Low Pass Filter ? Three Separate Interrupts on TX Complete, TX Data Register Empty and RX Complete ? Multi-processor Communication Mode ? Double Speed Asynchronous Communica

### UDR - USART I/O Data Register

`sfrb UDR = $C6;`

##### UDR00 - USART I/O Data Register bit 0

`#define UDR00_BIT 0`

`#define UDR00_MASK 1`

##### UDR01 - USART I/O Data Register bit 1

`#define UDR01_BIT 1`

`#define UDR01_MASK 2`

##### UDR02 - USART I/O Data Register bit 2

`#define UDR02_BIT 2`

`#define UDR02_MASK 4`

##### UDR03 - USART I/O Data Register bit 3

`#define UDR03_BIT 3`

`#define UDR03_MASK 8`

##### UDR04 - USART I/O Data Register bit 4

`#define UDR04_BIT 4`

`#define UDR04_MASK 16`

##### UDR05 - USART I/O Data Register bit 5

`#define UDR05_BIT 5`

`#define UDR05_MASK 32`

##### UDR06 - USART I/O Data Register bit 6

`#define UDR06_BIT 6`

`#define UDR06_MASK 64`

##### UDR07 - USART I/O Data Register bit 7

`#define UDR07_BIT 7`

`#define UDR07_MASK 128`

### UCSRA - USART Control and Status Register A

`sfrb UCSRA = $C0;`

##### MPCM - Multi-processor Communication Mode

`#define MPCM_BIT 0`

`#define MPCM_MASK 1`

This bit enables the Multi-processor Communication Mode. When the MPCM bit is written to one, all the incoming frames received by the USART receiver that do not contain address information will be ignored. The transmitter is unaffected by the MPCM setting. For more detailed information see ?Multi-processor Communication Mode? on page 152.

##### U2X - Double the USART Transmission Speed

`#define U2X_BIT 1`

`#define U2X_MASK 2`

This bit only has effect for the asynchronous operation. Write this bit to zero when using synchronous operation. Writing this bit to one will reduce the divisor of the baud rate divider from 16 to 8 effectively doubling the transfer rate for asynchronous communication.

##### UPE - USART Parity Error

`#define UPE_BIT 2`

`#define UPE_MASK 4`

This bit is set if the next character in the receive buffer had a Parity Error when received and the parity checking was enabled at that point (UPM1 = 1). This bit is valid until the receive buffer (UDR0) is read. Always set this bit to zero when writing to UCSR0A.

##### DOR - Data OverRun

`#define DOR_BIT 3`

`#define DOR_MASK 8`

This bit is set if an Overrun condition is detected, i.e. when a character already present in the UDRregister is not read before the next character has been shifted into the Receiver Shift register. The OR bit is buffered, which means that it will be set once the valid data still in UDR0E is read. The OR bit is cleared (zero) when data is received and transferred to UDR0.

##### FE - Framing Error

`#define FE_BIT 4`

`#define FE_MASK 16`

This bit is set if a Framing Error condition is detected, i.e. when the stop bit of an incoming character is zero. The FE bit is cleared when the stop bit of received data is one.

##### UDRE - USART Data Register Empty

`#define UDRE_BIT 5`

`#define UDRE_MASK 32`

This bit is set (one) when a character written to UDRis transferred to the Transmit shift register. Setting of this bit indicates that the transmitter is ready to receive a new character for transmission. When the UDR0IE bit in UCR is set, the USART Transmit Complete interrupt to be executed as long as UDR0E is set. UDR0E is cleared by writing UDR0. When interrupt-driven data transmittal is used, the USART Data Register Empty Interrupt routine must write UDRin order to clear UDR0E, otherwise a new interrupt will occur once the interrupt routine terminates. UDR0E is set (one) during reset to indicate that the transmitter is r

##### TXC - USART Transmit Complete

`#define TXC_BIT 6`

`#define TXC_MASK 64`

This bit is set (one) when the entire character (including the stop bit) in the Transmit Shift register has been shifted out and no new data has been written to UDR0. This flag is especially useful in half-duplex communications interfaces, where a transmitting application must enter receive mode and free the communications bus immediately after completing the transmission. When the TXCIE bit in UCR is set, setting of TXC causes the USART Transmit Complete interrupt to be executed. TXC is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, the TXC bit is cleared (zero) by writing a logical one to the b

##### RXC - USART Receive Complete

`#define RXC_BIT 7`

`#define RXC_MASK 128`

This bit is set (one) when a received character is transferred from the Receiver Shift register to UDR0. The bit is set regard-less of any detected framing errors. When the RXCIE bit in UCR is set, the USART Receive Complete interrupt will be executed when RXC is set(one). RXC is cleared by reading UDR0. When interrupt-driven data reception is used, the USART Receive Complete Interrupt routine must read UDRin order to clear RXC, otherwise a new interrupt will occur once the interrupt routine terminates.

### UCSRB - USART Control and Status Register B

`sfrb UCSRB = $C1;`

##### TXB8 - Transmit Data Bit 8

`#define TXB8_BIT 0`

`#define TXB8_MASK 1`

TXB8 is the 9th data bit in the character to be transmitted when operating with serial frames with 9 data bits. Must be writ-ten before writing the low bits to UDR0.

##### RXB8 - Receive Data Bit 8

`#define RXB8_BIT 1`

`#define RXB8_MASK 2`

RXB8 is the 9th data bit of the received character when operating with serial frames with 9 data bits. Must be read before reading the low bits from UDR0.

##### UCSZ2 - Character Size

`#define UCSZ2_BIT 2`

`#define UCSZ2_MASK 4`

The UCSZ2 bits combined with the UCSZ1:0 bit in UCSR0C sets the number of data bits (character size) in a frame the receiver and transmitter use.

##### TXEN - Transmitter Enable

`#define TXEN_BIT 3`

`#define TXEN_MASK 8`

Writing this bit to one enables the USART transmitter. The transmitter will override normal port operation for the TxD pin when enabled. The disabling of the transmitter (writing TXEN to zero) will not become effective until ongoing and pending transmissions are completed, i.e. when the transmit shift register and transmit buffer register does not contain data to be transmitted. When disabled, the transmitter will no longer override the TxD port.

##### RXEN - Receiver Enable

`#define RXEN_BIT 4`

`#define RXEN_MASK 16`

Writing this bit to one enables the USART receiver. The receiver will override normal port operation for the RxD pin when enabled. Disabling the receiver will flush the receive buffer invalidating the FE, DOR and PE flags.

##### UDRIE - USART Data Register Empty Interrupt Enable

`#define UDRIE_BIT 5`

`#define UDRIE_MASK 32`

Writing this bit to one enables interrupt on the UDR0E flag. A Data Register Empty interrupt will be generated only if the UDR0IE bit is written to one, the global interrupt flag in SREG is written to one and the UDR0E bit in UCSR0A is set.

##### TXCIE - TX Complete Interrupt Enable

`#define TXCIE_BIT 6`

`#define TXCIE_MASK 64`

Writing this bit to one enables interrupt on the TXC flag. A USART Transmit Complete interrupt will be generated only if the TXCIE bit is written to one, the global interrupt flag in SREG is written to one and the TXC bit in UCSR0A is set.

##### RXCIE - RX Complete Interrupt Enable

`#define RXCIE_BIT 7`

`#define RXCIE_MASK 128`

Writing this bit to one enables interrupt on the RXC flag. A USART Receive Complete interrupt will be generated only if the RXCIE bit is written to one, the global interrupt flag in SREG is written to one and the RXC bit in UCSR0A is set.

### UCSRC - USART Control and Status Register C

`sfrb UCSRC = $C2;`

##### UCPOL - Clock Polarity

`#define UCPOL_BIT 0`

`#define UCPOL_MASK 1`

This bit is used for synchronous mode only. Write this bit to zero when asynchronous mode is used. The UCPOL bit sets the relationship between data output change and data input sample, and the synchronous clock (XCK).

##### UCSZ0 - Character Size

`#define UCSZ0_BIT 1`

`#define UCSZ0_MASK 2`

Character Size: 0 0 0 = 5-bit. 0 0 1 = 6-bit. 0 1 0 = 7 bit. 0 1 1 = 8-bit. 1 1 1 = 9 bit.

##### UCSZ1 - Character Size

`#define UCSZ1_BIT 2`

`#define UCSZ1_MASK 4`

Character Size: 0 0 0 = 5-bit. 0 0 1 = 6-bit. 0 1 0 = 7 bit. 0 1 1 = 8-bit. 1 1 1 = 9 bit.

##### USBS - Stop Bit Select

`#define USBS_BIT 3`

`#define USBS_MASK 8`

0: 1-bit. 1: 2-bit.

##### UPM0 - Parity Mode Bit 0

`#define UPM0_BIT 4`

`#define UPM0_MASK 16`

This bit enable and set type of parity generation and check. If enabled, the transmitter will automatically generate and send the parity of the transmitted data bits within each frame. The receiver will generate a parity value for the incoming data and compare it to the UPM0 setting. If a mismatch is detected, the PE flag in UCSR0A will be set.

##### UPM1 - Parity Mode Bit 1

`#define UPM1_BIT 5`

`#define UPM1_MASK 32`

This bit enable and set type of parity generation and check. If enabled, the transmitter will automatically generate and send the parity of the transmitted data bits within each frame. The receiver will generate a parity value for the incoming data and compare it to the UPM0 setting. If a mismatch is detected, the PE flag in UCSR0A will be set.

##### UMSEL - USART Mode Select

`#define UMSEL_BIT 6`

`#define UMSEL_MASK 64`

0: Asynchronous Operation. 1: Synchronous Operation

### UBRRH - USART Baud Rate Register High Byte

`sfrb UBRRH = $C5;`

##### UBRR8 - USART Baud Rate Register bit 8

`#define UBRR8_BIT 0`

`#define UBRR8_MASK 1`

##### UBRR9 - USART Baud Rate Register bit 9

`#define UBRR9_BIT 1`

`#define UBRR9_MASK 2`

##### UBRR10 - USART Baud Rate Register bit 10

`#define UBRR10_BIT 2`

`#define UBRR10_MASK 4`

##### UBRR11 - USART Baud Rate Register bit 11

`#define UBRR11_BIT 3`

`#define UBRR11_MASK 8`

### UBRRL - USART Baud Rate Register Low Byte

`sfrb UBRRL = $C4;`

##### UBRR0 - USART Baud Rate Register bit 0

`#define UBRR0_BIT 0`

`#define UBRR0_MASK 1`

##### UBRR1 - USART Baud Rate Register bit 1

`#define UBRR1_BIT 1`

`#define UBRR1_MASK 2`

##### UBRR2 - USART Baud Rate Register bit 2

`#define UBRR2_BIT 2`

`#define UBRR2_MASK 4`

##### UBRR3 - USART Baud Rate Register bit 3

`#define UBRR3_BIT 3`

`#define UBRR3_MASK 8`

##### UBRR4 - USART Baud Rate Register bit 4

`#define UBRR4_BIT 4`

`#define UBRR4_MASK 16`

##### UBRR5 - USART Baud Rate Register bit 5

`#define UBRR5_BIT 5`

`#define UBRR5_MASK 32`

##### UBRR6 - USART Baud Rate Register bit 6

`#define UBRR6_BIT 6`

`#define UBRR6_MASK 64`

##### UBRR7 - USART Baud Rate Register bit 7

`#define UBRR7_BIT 7`

`#define UBRR7_MASK 128`

## CPU

### SREG - Status Register

`sfrb SREG = $3F;`

### SPH - Stack Pointer High

`sfrb SPH = $3E;`

##### SP8 - Stack pointer bit 8

`#define SP8_BIT 0`

`#define SP8_MASK 1`

##### SP9 - Stack pointer bit 9

`#define SP9_BIT 1`

`#define SP9_MASK 2`

##### SP10 - Stack pointer bit 10

`#define SP10_BIT 2`

`#define SP10_MASK 4`

##### SP11 - Stack pointer bit 11

`#define SP11_BIT 3`

`#define SP11_MASK 8`

##### SP12

`#define SP12_BIT 4`

`#define SP12_MASK 16`

##### SP13 - Stack pointer bit 13

`#define SP13_BIT 5`

`#define SP13_MASK 32`

##### SP14 - Stack pointer bit 14

`#define SP14_BIT 6`

`#define SP14_MASK 64`

##### SP15 - Stack pointer bit 15

`#define SP15_BIT 7`

`#define SP15_MASK 128`

### SPL - Stack Pointer Low

`sfrb SPL = $3D;`

##### SP0 - Stack pointer bit 0

`#define SP0_BIT 0`

`#define SP0_MASK 1`

##### SP1 - Stack pointer bit 1

`#define SP1_BIT 1`

`#define SP1_MASK 2`

##### SP2 - Stack pointer bit 2

`#define SP2_BIT 2`

`#define SP2_MASK 4`

##### SP3 - Stack pointer bit 3

`#define SP3_BIT 3`

`#define SP3_MASK 8`

##### SP4

`#define SP4_BIT 4`

`#define SP4_MASK 16`

##### SP5 - Stack pointer bit 5

`#define SP5_BIT 5`

`#define SP5_MASK 32`

##### SP6 - Stack pointer bit 6

`#define SP6_BIT 6`

`#define SP6_MASK 64`

##### SP7 - Stack pointer bit 7

`#define SP7_BIT 7`

`#define SP7_MASK 128`

### MCUCR - MCU Control Register

`sfrb MCUCR = $35;`

##### IVCE - Interrupt Vector Change Enable

`#define IVCE_BIT 0`

`#define IVCE_MASK 1`

The IVCE bit must be written to logic one to enable change of the IVSEL bit.IVCE is cleared by hardware four cycles after it is written or when IVSEL is written.Setting the IVCE bit will disable interrupts.

##### IVSEL - Interrupt Vector Select

`#define IVSEL_BIT 1`

`#define IVSEL_MASK 2`

When the IVSEL bit is cleared (zero),the interrupt vectors are placed at the start of the Flash memory.When this bit is set (one),the interrupt vectors are moved to the beginning of the Boot Loader section of the flash.The actual address of the start of the boot flash section is determined by the BOOTSZ fuses.

##### PUD - Pull-up disable

`#define PUD_BIT 4`

`#define PUD_MASK 16`

When this bit is written to one,the pull-ups in the I/O ports are disabled even if the DDxn and PORTxn registers are configured to enable the pull-ups ({DDxn,PORTxn}=0b01).

### MCUSR - MCU Status Register

`sfrb MCUSR = $34;`

##### PORF - Power-on reset flag

`#define PORF_BIT 0`

`#define PORF_MASK 1`

This bit is set if a power-on reset occurs. The bit is reset only by writing a logic zero to the flag. To make use of the reset flags to identify a reset condition, the user should read and then reset the MCUCSR as early as possible in the program. If the register is cleared before another reset occurs, the source of the reset can be found by examining the reset flags.

##### EXTRF - External Reset Flag

`#define EXTRF_BIT 1`

`#define EXTRF_MASK 2`

This bit is set if an external reset occurs. The bit is reset by a power-on reset, or by writing a logic zero to the flag.

##### BORF - Brown-out Reset Flag

`#define BORF_BIT 2`

`#define BORF_MASK 4`

This bit is set if a brown-out reset occurs. The bit is reset by a power-on reset, or by writing a logic zero to the flag.

##### WDRF - Watchdog Reset Flag

`#define WDRF_BIT 3`

`#define WDRF_MASK 8`

This bit is set if a watchdog reset occurs. The bit is reset by a power-on reset, or by writing a logic zero to the flag.

##### JTRF - JTAG Reset Flag

`#define JTRF_BIT 4`

`#define JTRF_MASK 16`

This bit is set if a reset is being caused by a logic one in the JTAG Reset Register selected by the JTAG instruction AVR_RESET. This bit is reset by a Power-on reset, or by writing a logic zero to the flag. ? Bit 3 - WDRF: Watchdog Reset Flag

### OSCCAL - Oscillator Calibration Value

`sfrb OSCCAL = $66;`

##### CAL0 - Oscillator Calibration Value Bit0

`#define CAL0_BIT 0`

`#define CAL0_MASK 1`

##### CAL1 - Oscillator Calibration Value Bit1

`#define CAL1_BIT 1`

`#define CAL1_MASK 2`

##### CAL2 - Oscillator Calibration Value Bit2

`#define CAL2_BIT 2`

`#define CAL2_MASK 4`

##### CAL3 - Oscillator Calibration Value Bit3

`#define CAL3_BIT 3`

`#define CAL3_MASK 8`

##### CAL4 - Oscillator Calibration Value Bit4

`#define CAL4_BIT 4`

`#define CAL4_MASK 16`

##### CAL5 - Oscillator Calibration Value Bit5

`#define CAL5_BIT 5`

`#define CAL5_MASK 32`

##### CAL6 - Oscillator Calibration Value Bit6

`#define CAL6_BIT 6`

`#define CAL6_MASK 64`

##### CAL7 - Oscillator Calibration Value Bit7

`#define CAL7_BIT 7`

`#define CAL7_MASK 128`

### CLKPR - Clock Prescale Register

`sfrb CLKPR = $61;`

##### CLKPS0 - Clock Prescaler Select Bit 0

`#define CLKPS0_BIT 0`

`#define CLKPS0_MASK 1`

##### CLKPS1 - Clock Prescaler Select Bit 1

`#define CLKPS1_BIT 1`

`#define CLKPS1_MASK 2`

##### CLKPS2 - Clock Prescaler Select Bit 2

`#define CLKPS2_BIT 2`

`#define CLKPS2_MASK 4`

##### CLKPS3 - Clock Prescaler Select Bit 3

`#define CLKPS3_BIT 3`

`#define CLKPS3_MASK 8`

##### CLKPCE - Clock Prescaler Change Enable

`#define CLKPCE_BIT 7`

`#define CLKPCE_MASK 128`

### PRR - Power Reduction Register

`sfrb PRR = $64;`

##### PRADC - Power Reduction ADC

`#define PRADC_BIT 0`

`#define PRADC_MASK 1`

##### PRUSART0 - Power Reduction USART

`#define PRUSART0_BIT 1`

`#define PRUSART0_MASK 2`

##### PRSPI - Power Reduction Serial Peripheral Interface

`#define PRSPI_BIT 2`

`#define PRSPI_MASK 4`

##### PRTIM1 - Power Reduction Timer/Counter1

`#define PRTIM1_BIT 3`

`#define PRTIM1_MASK 8`

### SMCR - Sleep Mode Control Register

`sfrb SMCR = $33;`

##### SE - Sleep Enable

`#define SE_BIT 0`

`#define SE_MASK 1`

The SE bit must be written to logic one to make the MCU enter the sleep mode when the SLEEP instruction is executed.To

##### SM0 - Sleep Mode Select bit 0

`#define SM0_BIT 1`

`#define SM0_MASK 2`

These bits select between the five available sleep modes.

##### SM1 - Sleep Mode Select bit 1

`#define SM1_BIT 2`

`#define SM1_MASK 4`

These bits select between the five available sleep modes.

##### SM2 - Sleep Mode Select bit 2

`#define SM2_BIT 3`

`#define SM2_MASK 8`

These bits select between the five available sleep modes.

### GPIOR2 - General Purpose IO Register 2

`sfrb GPIOR2 = $2B;`

##### GPIOR20 - General Purpose IO Register 2 bit 0

`#define GPIOR20_BIT 0`

`#define GPIOR20_MASK 1`

##### GPIOR21 - General Purpose IO Register 2 bit 1

`#define GPIOR21_BIT 1`

`#define GPIOR21_MASK 2`

##### GPIOR22 - General Purpose IO Register 2 bit 2

`#define GPIOR22_BIT 2`

`#define GPIOR22_MASK 4`

##### GPIOR23 - General Purpose IO Register 2 bit 3

`#define GPIOR23_BIT 3`

`#define GPIOR23_MASK 8`

##### GPIOR24 - General Purpose IO Register 2 bit 4

`#define GPIOR24_BIT 4`

`#define GPIOR24_MASK 16`

##### GPIOR25 - General Purpose IO Register 2 bit 5

`#define GPIOR25_BIT 5`

`#define GPIOR25_MASK 32`

##### GPIOR26 - General Purpose IO Register 2 bit 6

`#define GPIOR26_BIT 6`

`#define GPIOR26_MASK 64`

##### GPIOR27 - General Purpose IO Register 2 bit 7

`#define GPIOR27_BIT 7`

`#define GPIOR27_MASK 128`

### GPIOR1 - General Purpose IO Register 1

`sfrb GPIOR1 = $2A;`

##### GPIOR10 - General Purpose IO Register 1 bit 0

`#define GPIOR10_BIT 0`

`#define GPIOR10_MASK 1`

##### GPIOR11 - General Purpose IO Register 1 bit 1

`#define GPIOR11_BIT 1`

`#define GPIOR11_MASK 2`

##### GPIOR12 - General Purpose IO Register 1 bit 2

`#define GPIOR12_BIT 2`

`#define GPIOR12_MASK 4`

##### GPIOR13 - General Purpose IO Register 1 bit 3

`#define GPIOR13_BIT 3`

`#define GPIOR13_MASK 8`

##### GPIOR14 - General Purpose IO Register 1 bit 4

`#define GPIOR14_BIT 4`

`#define GPIOR14_MASK 16`

##### GPIOR15 - General Purpose IO Register 1 bit 5

`#define GPIOR15_BIT 5`

`#define GPIOR15_MASK 32`

##### GPIOR16 - General Purpose IO Register 1 bit 6

`#define GPIOR16_BIT 6`

`#define GPIOR16_MASK 64`

##### GPIOR17 - General Purpose IO Register 1 bit 7

`#define GPIOR17_BIT 7`

`#define GPIOR17_MASK 128`

### GPIOR0 - General Purpose IO Register 0

`sfrb GPIOR0 = $1E;`

##### GPIOR00 - General Purpose IO Register 0 bit 0

`#define GPIOR00_BIT 0`

`#define GPIOR00_MASK 1`

##### GPIOR01 - General Purpose IO Register 0 bit 1

`#define GPIOR01_BIT 1`

`#define GPIOR01_MASK 2`

##### GPIOR02 - General Purpose IO Register 0 bit 2

`#define GPIOR02_BIT 2`

`#define GPIOR02_MASK 4`

##### GPIOR03 - General Purpose IO Register 0 bit 3

`#define GPIOR03_BIT 3`

`#define GPIOR03_MASK 8`

##### GPIOR04 - General Purpose IO Register 0 bit 4

`#define GPIOR04_BIT 4`

`#define GPIOR04_MASK 16`

##### GPIOR05 - General Purpose IO Register 0 bit 5

`#define GPIOR05_BIT 5`

`#define GPIOR05_MASK 32`

##### GPIOR06 - General Purpose IO Register 0 bit 6

`#define GPIOR06_BIT 6`

`#define GPIOR06_MASK 64`

##### GPIOR07 - General Purpose IO Register 0 bit 7

`#define GPIOR07_BIT 7`

`#define GPIOR07_MASK 128`