This documentation was generated automatically from the AVR Studio part description file AT90S4434.pdf.

TIMER COUNTER 0

The 8-bit Timer/Counter0 can select clock source from CK, prescaled CK, or an external pin. In addition it can be stopped as described in ?Timer/Counter0 Control Register - TCCR0? on page 35. The overflow status flag is found in ?The Timer/Counter Interrupt Flag Register - TIFR? on page 29. Control signals are found in the Timer/Counter0 Control Register - TCCR0. The interrupt enable/disable settings for Timer/Counter0 are found in ?The Timer/Counter Interrupt Mask Regis-ter - TIMSK? on page 28. When Timer/Counter0 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. The 8-bit Timer/Counter0 features both a high resolution and a high accuracy usage with the lower prescaling opportuni-ties. Similarly, the high prescaling opportuni ties make the Timer/Counter0 useful for lower speed functions or exact timing functions with infrequent actions

TIMSK - Timer/Counter Interrupt Mask Register

sfrb TIMSK = $39;

TOIE0 - Timer/Counter0 Overflow Interrupt Enable

#define TOIE0 0

When the TOIE0 bit is set (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.

TIFR - Timer/Counter Interrupt Flag register

sfrb TIFR = $38;

TOV0 - Timer/Counter0 Overflow Flag

#define TOV0 0

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, and TOIE0 (Timer/Counter0 Overflow Interrupt Enable), and TOV0 are set (one), the Timer/Counter0 Overflow interrupt is executed.

TCCR0 - Timer/Counter0 Control Register

sfrb TCCR0 = $33;

CS00 - Clock Select0 bit 0

#define CS00 0

CS01 - Clock Select0 bit 1

#define CS01 1

CS02 - Clock Select0 bit 2

#define CS02 2

TCNT0 - Timer Counter 0

sfrb TCNT0 = $32;

TCNT00 - Timer Counter 0 bit 0

#define TCNT00 0

TCNT01 - Timer Counter 0 bit 1

#define TCNT01 1

TCNT02 - Timer Counter 0 bit 2

#define TCNT02 2

TCNT03 - Timer Counter 0 bit 3

#define TCNT03 3

TCNT04 - Timer Counter 0 bit 4

#define TCNT04 4

TCNT05 - Timer Counter 0 bit 5

#define TCNT05 5

TCNT06 - Timer Counter 0 bit 6

#define TCNT06 6

TCNT07 - Timer Counter 0 bit 7

#define TCNT07 7

TIMER COUNTER 1

The 16-bit Timer/Counter1 can select clock source from CK, prescaled CK, or an external pin. In addition it can be stopped as described in the specification for the Timer/Counter1 Control Registers - TCCR1A and TCCR1B. The different status flags (overflow, compare match and capture event) are found in the Timer/Counter Interrupt Flag Register - TIFR. Control signals are found in the Timer/Counter1 Control Registers - TCCR1A and TCCR1B. The interrupt enable/disable settings for Timer/Counter1 are found in the Timer/Counter Interrupt Mask Register - TIMS

TIMSK - Timer/Counter Interrupt Mask Register

sfrb TIMSK = $39;

TOIE1 - Timer/Counter1 Overflow Interrupt Enable

#define TOIE1 2

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.

OCIE1B - Timer/Counter1 Output CompareB Match Interrupt Enable

#define OCIE1B 3

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.

OCIE1A - Timer/Counter1 Output CompareA Match Interrupt Enable

#define OCIE1A 4

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.

TICIE1 - Timer/Counter1 Input Capture Interrupt Enable

#define TICIE1 5

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.

TIFR - Timer/Counter Interrupt Flag register

sfrb TIFR = $38;

TOV1 - Timer/Counter1 Overflow Flag

#define TOV1 2

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.

OCF1B - Output Compare Flag 1B

#define OCF1B 3

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.

OCF1A - Output Compare Flag 1A

#define OCF1A 4

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.

ICF1 - Input Capture Flag 1

#define ICF1 5

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.

TCCR1A - Timer/Counter1 Control Register A

sfrb TCCR1A = $2F;

PWM10 - Pulse Width Modulator Select Bit 0

#define PWM10 0

PWM11 - Pulse Width Modulator Select Bit 1

#define PWM11 1

COM1B0 - Compare Output Mode 1B, bit 0

#define COM1B0 4

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.

COM1B1 - Compare Output Mode 1B, bit 1

#define COM1B1 5

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.

COM1A0 - Compare Ouput Mode 1A, bit 0

#define COM1A0 6

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 pin 1. This is an alternative function to an I/O port and the corresponding direction control bit must be set (one) to control the output pin. The control configuration is shown in Table 9.

COM1A1 - Compare Output Mode 1A, bit 1

#define COM1A1 7

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 pin 1. This is an alternative function to an I/O port and the corresponding direction control bit must be set (one) to control the output pin. The control configuration is shown in Table 9.

TCCR1B - Timer/Counter1 Control Register B

sfrb TCCR1B = $2E;

CS10 - Clock Select1 bit 0

#define CS10 0

CS11 - Clock Select1 bit 1

#define CS11 1

CS12 - Clock Select1 bit 2

#define CS12 2

CTC1 - Clear Timer/Counter1 on Compare Match

#define CTC1 3

When the CTC1 control bit is set (one), the Timer/Counter1 is reset to $0000 in the clock cycle after a compareA match. If the CTC1 control bit is cleared, Timer/Counter1 continues counting and is unaffected by a compare match. Since the compare match is detected in the CPU clock cycle following the match, this function will behave differently when a prescal-ing higher than 1 is used for the timer. When a prescaling of 1 is used, and the compareA register is set to C, the timer will count as follows if CTC1 is set: ...|C-2 |C-1 |C |0|1 |... When the prescaler is set to divide by 8, the timer will count like this: ... | C-2, C-2, C-2, C-2, C-2, C-2, C-2, C-2 | C-1, C-1, C-1, C-1, C-1, C-1, C-1, C-1 | C, 0, 0, 0, 0, 0, 0, 0 | ... In PWM mode, this bit has no effect

ICES1 - Input Capture 1 Edge Select

#define ICES1 6

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 7

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.

TCNT1H - Timer/Counter1 High Byte

sfrb TCNT1H = $2D;

TCNT1H0 - Timer/Counter1 High Byte bit 0

#define TCNT1H0 0

TCNT1H1 - Timer/Counter1 High Byte bit 1

#define TCNT1H1 1

TCNT1H2 - Timer/Counter1 High Byte bit 2

#define TCNT1H2 2

TCNT1H3 - Timer/Counter1 High Byte bit 3

#define TCNT1H3 3

TCNT1H4 - Timer/Counter1 High Byte bit 4

#define TCNT1H4 4

TCNT1H5 - Timer/Counter1 High Byte bit 5

#define TCNT1H5 5

TCNT1H6 - Timer/Counter1 High Byte bit 6

#define TCNT1H6 6

TCNT1H7 - Timer/Counter1 High Byte bit 7

#define TCNT1H7 7

TCNT1L - Timer/Counter1 Low Byte

sfrb TCNT1L = $2C;

TCNT1L0 - Timer/Counter1 Low Byte bit 0

#define TCNT1L0 0

TCNT1L1 - Timer/Counter1 Low Byte bit 1

#define TCNT1L1 1

TCNT1L2 - Timer/Counter1 Low Byte bit 2

#define TCNT1L2 2

TCNT1L3 - Timer/Counter1 Low Byte bit 3

#define TCNT1L3 3

TCNT1L4 - Timer/Counter1 Low Byte bit 4

#define TCNT1L4 4

TCNT1L5 - Timer/Counter1 Low Byte bit 5

#define TCNT1L5 5

TCNT1L6 - Timer/Counter1 Low Byte bit 6

#define TCNT1L6 6

TCNT1L7 - Timer/Counter1 Low Byte bit 7

#define TCNT1L7 7

OCR1AH - Timer/Counter1 Outbut Compare Register High Byte

sfrb OCR1AH = $2B;

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

#define OCR1AH0 0

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

#define OCR1AH1 1

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

#define OCR1AH2 2

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

#define OCR1AH3 3

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

#define OCR1AH4 4

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

#define OCR1AH5 5

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

#define OCR1AH6 6

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

#define OCR1AH7 7

OCR1AL - Timer/Counter1 Output Compare Register Low Byte

sfrb OCR1AL = $2A;

OCR1AL0 - Timer/Counter1 Output Compare Register Low Byte Bit 0

#define OCR1AL0 0

OCR1AL1 - Timer/Counter1 Output Compare Register Low Byte Bit 1

#define OCR1AL1 1

OCR1AL2 - Timer/Counter1 Output Compare Register Low Byte Bit 2

#define OCR1AL2 2

OCR1AL3 - Timer/Counter1 Output Compare Register Low Byte Bit 3

#define OCR1AL3 3

OCR1AL4 - Timer/Counter1 Output Compare Register Low Byte Bit 4

#define OCR1AL4 4

OCR1AL5 - Timer/Counter1 Output Compare Register Low Byte Bit 5

#define OCR1AL5 5

OCR1AL6 - Timer/Counter1 Output Compare Register Low Byte Bit 6

#define OCR1AL6 6

OCR1AL7 - Timer/Counter1 Output Compare Register Low Byte Bit 7

#define OCR1AL7 7

OCR1BH - Timer/Counter1 Output Compare Register High Byte

sfrb OCR1BH = $29;

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

#define OCR1BH0 0

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

#define OCR1BH1 1

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

#define OCR1BH2 2

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

#define OCR1BH3 3

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

#define OCR1BH4 4

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

#define OCR1BH5 5

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

#define OCR1BH6 6

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

#define OCR1BH7 7

OCR1BL - Timer/Counter1 Output Compare Register Low Byte

sfrb OCR1BL = $28;

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

#define OCR1BL0 0

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

#define OCR1BL1 1

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

#define OCR1BL2 2

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

#define OCR1BL3 3

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

#define OCR1BL4 4

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

#define OCR1BL5 5

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

#define OCR1BL6 6

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

#define OCR1BL7 7

ICR1H - Timer/Counter1 Input Capture Register High Byte

sfrb ICR1H = $27;

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

#define ICR1H0 0

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

#define ICR1H1 1

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

#define ICR1H2 2

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

#define ICR1H3 3

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

#define ICR1H4 4

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

#define ICR1H5 5

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

#define ICR1H6 6

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

#define ICR1H7 7

ICR1L - Timer/Counter1 Input Capture Register Low Byte

sfrb ICR1L = $26;

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

#define ICR1L0 0

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

#define ICR1L1 1

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

#define ICR1L2 2

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

#define ICR1L3 3

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

#define ICR1L4 4

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

#define ICR1L5 5

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

#define ICR1L6 6

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

#define ICR1L7 7

TIMER COUNTER 2

TCCR2 - Timer/Counter Control Register

sfrb TCCR2 = $25;

CS20 - Clock Select

#define CS20 0

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

CS21 - Clock Select

#define CS21 1

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

CS22 - Clock Select

#define CS22 2

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

CTC2 - Clear Timer/Counter Compare Match

#define CTC2 3

Please refer to manual.

COM20 - Compare Match Output Mode

#define COM20 4

These bits control the output compare pin (OC2) behavior. If one or both of the COM21:0 bits are set, the OC2 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 OC2 pin must be set in order to enable the output driver. When OC2 is connected to the pin, the function of the COM21:0 bits depends on the WGM21:0 bit setting. Table 64 shows the COM21:0 bit functionality when the WGM21:0 bits are set to a normal or CTC mode (non-PWM)

COM21 - Compare Match Output Mode

#define COM21 5

These bits control the output compare pin (OC2) behavior. If one or both of the COM21:0 bits are set, the OC2 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 OC2 pin must be set in order to enable the output driver. When OC2 is connected to the pin, the function of the COM21:0 bits depends on the WGM21:0 bit setting. Table 64 shows the COM21:0 bit functionality when the WGM21:0 bits are set to a normal or CTC mode (non-PWM).

PWM2 - Pulse Width Modulator Enable

#define PWM2 6

When set (one), this bit enables PWM mode for Timer/Counter2.

TCNT2 - Timer/Counter Register

sfrb TCNT2 = $24;

TCNT2_0 - Timer/Counter Register Bit 0

#define TCNT2_0 0

TCNT2_1 - Timer/Counter Register Bit 1

#define TCNT2_1 1

TCNT2_2 - Timer/Counter Register Bit 2

#define TCNT2_2 2

TCNT2_3 - Timer/Counter Register Bit 3

#define TCNT2_3 3

TCNT2_4 - Timer/Counter Register Bit 4

#define TCNT2_4 4

TCNT2_5 - Timer/Counter Register Bit 5

#define TCNT2_5 5

TCNT2_6 - Timer/Counter Register Bit 6

#define TCNT2_6 6

TCNT2_7 - Timer/Counter Register Bit 7

#define TCNT2_7 7

OCR2 - Output Compare Register

sfrb OCR2 = $23;

OCR2_0 - Output Compare Register Bit 0

#define OCR2_0 0

OCR2_1 - Output Compare Register Bit 1

#define OCR2_1 1

OCR2_2 - Output Compare Register Bit 2

#define OCR2_2 2

OCR2_3 - Output Compare Register Bit 3

#define OCR2_3 3

OCR2_4 - Output Compare Register Bit 4

#define OCR2_4 4

OCR2_5 - Output Compare Register Bit 5

#define OCR2_5 5

OCR2_6 - Output Compare Register Bit 6

#define OCR2_6 6

OCR2_7 - Output Compare Register Bit 7

#define OCR2_7 7

ASSR - Asynchronous Status Register

sfrb ASSR = $22;

TCR2UB - Timer/Counter Control Register2 Update Busy

#define TCR2UB 0

When Timer/Counter2 operates asynchronously and TCCR2 is written, this bit becomes set (one). When TCCR2 has been updated from the temporary storage register, this bit is cleared (zero) by hardware. A logical ?0? in this bit indicates that TCCR2 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 (one), the updated value might get corrupted and cause an unintentional interrupt to occur. The mechanisms for reading TCNT2, OCR2 and TCCR2 are different. When reading TCNT2, the actual timer value is read. When reading OCR2 or TCCR2, the value in the temporary storage register is rea

OCR2UB - Output Compare Register2 Update Busy

#define OCR2UB 1

When Timer/Counter2 operates asynchronously and OCR2 is written, this bit becomes set (one). When OCR2 has been updated from the temporary storage register, this bit is cleared (zero) by hardware. A logical ?0? in this bit indicates that OCR2 is ready to be updated with a new value.

TCN2UB - Timer/Counter2 Update Busy

#define TCN2UB 2

When Timer/Counter2 operates asynchronously and TCNT2 is written, this bit becomes set (one). When TCNT2 has been updated from the temporary storage register, this bit is cleared (zero) by hardware. A logical ?0? in this bit indicates that TCNT2 is ready to be updated with a new value.

AS2 - Asynchronous Timer 2

#define AS2 3

When AS2 is set (one), Timer/Counter2 is clocked from the TOSC1 pin. Pins PC6 and PC7 become connected to a crystal oscillator and cannot be used as general I/O pins. When cleared (zero), Timer/Counter2 is clocked from the internal system clock, CK. When the value of this bit is changed, the contents of TCNT2, OCR2 and TCCR2 might get corrupted.

TIMSK - Timer/Counter Interrupt Mask Register

sfrb TIMSK = $39;

TOIE2 - Timer/Counter2 Overflow Interrupt Enable

#define TOIE2 6

When the TOIE2 bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter2 Overflow interrupt is enabled. The corresponding interrupt (at vector $004) is executed if an overflow in Timer/Counter2 occurs (i.e., when the TOV2 bit is set in the Timer/Counter Interrupt Flag Register [TIFR]).

OCIE2 - Timer/Counter2 Output Compare Match Interrupt Enable

#define OCIE2 7

When the OCIE2 bit is set (one) and the I-bit in the Status Register is set (one), the Timer/Counter2 Compare Match inter-rupt is enabled. The corresponding interrupt (at vector $003) 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]).

TIFR - Timer/Counter Interrupt Flag Register

sfrb TIFR = $38;

TOV2 - Timer/Counter2 Overflow Flag

#define TOV2 6

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 logical ?1? to the flag. When the SREG I-bit and TOIE2 (Timer/Counter2 Overf low 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/Counter1 advances from $0000.

OCF2 - Output Compare Flag 2

#define OCF2 7

The OCF2 bit is set (one) when 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 logical ?1? 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.

UART

UDR - UART I/O Data Register

sfrb UDR = $0C;

UDR0 - UART I/O Data Register bit 0

#define UDR0 0

UDR1 - UART I/O Data Register bit 1

#define UDR1 1

UDR2 - UART I/O Data Register bit 2

#define UDR2 2

UDR3 - UART I/O Data Register bit 3

#define UDR3 3

UDR4 - UART I/O Data Register bit 4

#define UDR4 4

UDR5 - UART I/O Data Register bit 5

#define UDR5 5

UDR6 - UART I/O Data Register bit 6

#define UDR6 6

UDR7 - UART I/O Data Register bit 7

#define UDR7 7

USR - UART Status Register

sfrb USR = $0B;

OR - Overrun

#define OR 3

This bit is set if an Overrun condition is detected, i.e. when a character already present in the UDR register 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 UDRE is read. The OR bit is cleared (zero) when data is received and transferred to UDR.

FE - Framing Error

#define FE 4

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 - UART Data Register Empty

#define UDRE 5

This bit is set (one) when a character written to UDR is 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 UDRIE bit in UCR is set, the UART Transmit Complete interrupt to be executed as long as UDRE is set. UDRE is cleared by writing UDR. When interrupt-driven data transmittal is used, the UART Data Register Empty Interrupt routine must write UDR in order to clear UDRE, otherwise a new interrupt will occur once the interrupt routine terminates. UDRE is set (one) during reset to indicate that the transmitter is ready

TXC - UART Transmit Complete

#define TXC 6

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 UDR. 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 UART 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 bit

RXC - UART Receive Complete

#define RXC 7

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

UCR - UART Control Register

sfrb UCR = $0A;

TXB8 - Transmit Data Bit 8

#define TXB8 0

When CHR9 is set (one), TXB8 is the 9th data bit in the character to be transmitted.

RXB8 - Receive Data Bit 8

#define RXB8 1

When CHR9 is set (one), RXB8 is the 9th data bit of the received character.

CHR9 - 9-bit Characters

#define CHR9 2

When this bit is set (one) transmitted and received characters are 9 bit long plus start and stop bits. The 9th bit is read and written by using the RXB8 and TXB8 bits in UCR, respectively. The 9th data bit can be used as an extra stop bit or a parity bit.

TXEN - Transmitter Enable

#define TXEN 3

This bit enables the UART transmitter when set (one). When disabling the transmitter while transmitting a character, the transmitter is not disabled before the character in the shift register plus any following character in UDR has been completely transmitted.

RXEN - Receiver Enable

#define RXEN 4

This bit enables the UART receiver when set (one). When the receiver is disabled, the TXC, OR and FE status flags cannot become set. If these flags are set, turning off RXEN does not cause them to be cleared.

UDRIE - UART Data Register Empty Interrupt Enable

#define UDRIE 5

When this bit is set (one), a setting of the UDRE bit in USR will cause the UART Data Register Empty interrupt routine to be executed provided that global interrupts are enabled.

TXCIE - TX Complete Interrupt Enable

#define TXCIE 6

When this bit is set (one), a setting of the TXC bit in USR will cause the Transmit Complete interrupt routine to be executed provided that global interrupts are enabled.

RXCIE - RX Complete Interrupt Enable

#define RXCIE 7

When this bit is set (one), a setting of the RXC bit in USR will cause the Receive Complete interrupt routine to be executed provided that global interrupts are enabled.

UBRR - UART BAUD Rate Register

sfrb UBRR = $09;

UBRR0 - UART Baud Rate Register bit 0

#define UBRR0 0

UBRR1 - UART Baud Rate Register bit 1

#define UBRR1 1

UBRR2 - UART Baud Rate Register bit 2

#define UBRR2 2

UBRR3 - UART Baud Rate Register bit 3

#define UBRR3 3

UBRR4 - UART Baud Rate Register bit 4

#define UBRR4 4

UBRR5 - UART Baud Rate Register bit 5

#define UBRR5 5

UBRR6 - UART Baud Rate Register bit 6

#define UBRR6 6

UBRR7 - UART Baud Rate Register bit 7

#define UBRR7 7

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 = $0D;

SPR0 - SPI Clock Rate Select 0

#define SPR0 0

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 1

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 2

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

CPOL - Clock polarity

#define CPOL 3

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 4

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 5

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 6

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 7

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 = $0E;

WCOL - Write Collision Flag

#define WCOL 6

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 7

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 = $0F;

SPDR0 - SPI Data Register bit 0

#define SPDR0 0

SPDR1 - SPI Data Register bit 1

#define SPDR1 1

SPDR2 - SPI Data Register bit 2

#define SPDR2 2

SPDR3 - SPI Data Register bit 3

#define SPDR3 3

SPDR4 - SPI Data Register bit 4

#define SPDR4 4

SPDR5 - SPI Data Register bit 5

#define SPDR5 5

SPDR6 - SPI Data Register bit 6

#define SPDR6 6

SPDR7 - SPI Data Register bit 7

#define SPDR7 7

PORTA

PORTA - Port A Data Register

sfrb PORTA = $1B;

PORTA0 - Port A Data Register bit 0

#define PORTA0 0

PORTA1 - Port A Data Register bit 1

#define PORTA1 1

PORTA2 - Port A Data Register bit 2

#define PORTA2 2

PORTA3 - Port A Data Register bit 3

#define PORTA3 3

PORTA4 - Port A Data Register bit 4

#define PORTA4 4

PORTA5 - Port A Data Register bit 5

#define PORTA5 5

PORTA6 - Port A Data Register bit 6

#define PORTA6 6

PORTA7 - Port A Data Register bit 7

#define PORTA7 7

DDRA - Port A Data Direction Register

sfrb DDRA = $1A;

DDA0 - Data Direction Register, Port A, bit 0

#define DDA0 0

DDA1 - Data Direction Register, Port A, bit 1

#define DDA1 1

DDA2 - Data Direction Register, Port A, bit 2

#define DDA2 2

DDA3 - Data Direction Register, Port A, bit 3

#define DDA3 3

DDA4 - Data Direction Register, Port A, bit 4

#define DDA4 4

DDA5 - Data Direction Register, Port A, bit 5

#define DDA5 5

DDA6 - Data Direction Register, Port A, bit 6

#define DDA6 6

DDA7 - Data Direction Register, Port A, bit 7

#define DDA7 7

PINA - Port A Input Pins

sfrb PINA = $19;

PINA0 - Input Pins, Port A bit 0

#define PINA0 0

PINA1 - Input Pins, Port A bit 1

#define PINA1 1

PINA2 - Input Pins, Port A bit 2

#define PINA2 2

PINA3 - Input Pins, Port A bit 3

#define PINA3 3

PINA4 - Input Pins, Port A bit 4

#define PINA4 4

PINA5 - Input Pins, Port A bit 5

#define PINA5 5

PINA6 - Input Pins, Port A bit 6

#define PINA6 6

PINA7 - Input Pins, Port A bit 7

#define PINA7 7

PORTB

PORTB - Port B Data Register

sfrb PORTB = $18;

PORTB0 - Port B Data Register bit 0

#define PORTB0 0

PORTB1 - Port B Data Register bit 1

#define PORTB1 1

PORTB2 - Port B Data Register bit 2

#define PORTB2 2

PORTB3 - Port B Data Register bit 3

#define PORTB3 3

PORTB4 - Port B Data Register bit 4

#define PORTB4 4

PORTB5 - Port B Data Register bit 5

#define PORTB5 5

PORTB6 - Port B Data Register bit 6

#define PORTB6 6

PORTB7 - Port B Data Register bit 7

#define PORTB7 7

DDRB - Port B Data Direction Register

sfrb DDRB = $17;

DDB0 - Port B Data Direction Register bit 0

#define DDB0 0

DDB1 - Port B Data Direction Register bit 1

#define DDB1 1

DDB2 - Port B Data Direction Register bit 2

#define DDB2 2

DDB3 - Port B Data Direction Register bit 3

#define DDB3 3

DDB4 - Port B Data Direction Register bit 4

#define DDB4 4

DDB5 - Port B Data Direction Register bit 5

#define DDB5 5

DDB6 - Port B Data Direction Register bit 6

#define DDB6 6

DDB7 - Port B Data Direction Register bit 7

#define DDB7 7

PINB - Port B Input Pins

sfrb PINB = $16;

PINB0 - Port B Input Pins bit 0

#define PINB0 0

PINB1 - Port B Input Pins bit 1

#define PINB1 1

PINB2 - Port B Input Pins bit 2

#define PINB2 2

PINB3 - Port B Input Pins bit 3

#define PINB3 3

PINB4 - Port B Input Pins bit 4

#define PINB4 4

PINB5 - Port B Input Pins bit 5

#define PINB5 5

PINB6 - Port B Input Pins bit 6

#define PINB6 6

PINB7 - Port B Input Pins bit 7

#define PINB7 7

PORTC

PORTC - Port C Data Register

sfrb PORTC = $15;

PORTC0 - Port C Data Register bit 0

#define PORTC0 0

PORTC1 - Port C Data Register bit 1

#define PORTC1 1

PORTC2 - Port C Data Register bit 2

#define PORTC2 2

PORTC3 - Port C Data Register bit 3

#define PORTC3 3

PORTC4 - Port C Data Register bit 4

#define PORTC4 4

PORTC5 - Port C Data Register bit 5

#define PORTC5 5

PORTC6 - Port C Data Register bit 6

#define PORTC6 6

PORTC7 - Port C Data Register bit 7

#define PORTC7 7

DDRC - Port C Data Direction Register

sfrb DDRC = $14;

DDC0 - Port C Data Direction Register bit 0

#define DDC0 0

DDC1 - Port C Data Direction Register bit 1

#define DDC1 1

DDC2 - Port C Data Direction Register bit 2

#define DDC2 2

DDC3 - Port C Data Direction Register bit 3

#define DDC3 3

DDC4 - Port C Data Direction Register bit 4

#define DDC4 4

DDC5 - Port C Data Direction Register bit 5

#define DDC5 5

DDC6 - Port C Data Direction Register bit 6

#define DDC6 6

DDC7 - Port C Data Direction Register bit 7

#define DDC7 7

PINC - Port C Input Pins

sfrb PINC = $13;

PINC0 - Port C Input Pins bit 0

#define PINC0 0

PINC1 - Port C Input Pins bit 1

#define PINC1 1

PINC2 - Port C Input Pins bit 2

#define PINC2 2

PINC3 - Port C Input Pins bit 3

#define PINC3 3

PINC4 - Port C Input Pins bit 4

#define PINC4 4

PINC5 - Port C Input Pins bit 5

#define PINC5 5

PINC6 - Port C Input Pins bit 6

#define PINC6 6

PINC7 - Port C Input Pins bit 7

#define PINC7 7

PORTD

PORTD - Port D Data Register

sfrb PORTD = $12;

PORTD0 - Port D Data Register bit 0

#define PORTD0 0

PORTD1 - Port D Data Register bit 1

#define PORTD1 1

PORTD2 - Port D Data Register bit 2

#define PORTD2 2

PORTD3 - Port D Data Register bit 3

#define PORTD3 3

PORTD4 - Port D Data Register bit 4

#define PORTD4 4

PORTD5 - Port D Data Register bit 5

#define PORTD5 5

PORTD6 - Port D Data Register bit 6

#define PORTD6 6

PORTD7 - Port D Data Register bit 7

#define PORTD7 7

DDRD - Port D Data Direction Register

sfrb DDRD = $11;

DDD0 - Port D Data Direction Register bit 0

#define DDD0 0

DDD1 - Port D Data Direction Register bit 1

#define DDD1 1

DDD2 - Port D Data Direction Register bit 2

#define DDD2 2

DDD3 - Port D Data Direction Register bit 3

#define DDD3 3

DDD4 - Port D Data Direction Register bit 4

#define DDD4 4

DDD5 - Port D Data Direction Register bit 5

#define DDD5 5

DDD6 - Port D Data Direction Register bit 6

#define DDD6 6

DDD7 - Port D Data Direction Register bit 7

#define DDD7 7

PIND - Port D Input Pins

sfrb PIND = $10;

PIND0 - Port D Input Pins bit 0

#define PIND0 0

PIND1 - Port D Input Pins bit 1

#define PIND1 1

PIND2 - Port D Input Pins bit 2

#define PIND2 2

PIND3 - Port D Input Pins bit 3

#define PIND3 3

PIND4 - Port D Input Pins bit 4

#define PIND4 4

PIND5 - Port D Input Pins bit 5

#define PIND5 5

PIND6 - Port D Input Pins bit 6

#define PIND6 6

PIND7 - Port D Input Pins bit 7

#define PIND7 7

ANALOG COMPARATOR

The analog comparator compares the input values on the positive input PB2 (AIN0) and negative input PB3 (AIN1). When the voltage on the positive input PB2 (AIN0) is higher than the voltage on the negative input PB3 (AIN1), the Analog Com-parator Output, ACO is set (one). The comparator?s output can be set to trigger the Timer/Counter1 Input Capture function. In addition, the comparator can trigger a separate interrupt, exclusive to the Analog Comparator. The user can select Inter-rupt triggering on comparator output rise, fall or toggle

ACSR - Analog Comparator Control And Status Register

sfrb ACSR = $08;

ACIS0 - Analog Comparator Interrupt Mode Select bit 0

#define ACIS0 0

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

ACIS1 - Analog Comparator Interrupt Mode Select bit 1

#define ACIS1 1

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

ACIC - Analog Comparator Input Capture Enable

#define ACIC 2

When set (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 cleared (zero), no connection between the analog comparator and the Input Capture function is given. To make the comparator trigger the Timer/Counter1 Input Capture interrupt, the TICIE1 bit in the Timer Interrupt Mask Register (TIMSK) must be set (one)

ACIE - Analog Comparator Interrupt Enable

#define ACIE 3

When the ACIE bit is set (one) and the I-bit in the Status Register is set (one), the analog comparator interrupt is activated. When Cleared (Zero), the interrupt is disabled.

ACI - Analog Comparator Interrupt Flag

#define ACI 4

This bit is set (one) when a comparator output event triggers the interrupt mode defined by ACI1 and ACI0. The Analog Comparator Interrupt routine is executed if the ACIE bit is set (one) and the I-bit in SREG is set (one). ACI is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ACI is cleared by writing a logic one to the flag. Observe however, that if another bit in this register is modified using the SBI or CBI instruction, ACI will be cleared if it has become set before the operation

ACO - Analog Comparator Output

#define ACO 5

When this bit is set(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.

ACD - Analog Comparator Disable

#define ACD 7

When this bit is set(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.

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 Noise

ADMUX - The ADC multiplexer Selection Register

sfrb ADMUX = $07;

MUX0 - Analog Channel and Gain Selection Bits

#define MUX0 0

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 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).

MUX2 - Analog Channel and Gain Selection Bits

#define MUX2 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).

ADCSR - The ADC Control and Status register

sfrb ADCSR = $06;

ADPS0 - ADC Prescaler Select Bits

#define ADPS0 0

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

ADPS1 - ADC Prescaler Select Bits

#define ADPS1 1

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

ADPS2 - ADC Prescaler Select Bits

#define ADPS2 2

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

ADIE - ADC Interrupt Enable

#define ADIE 3

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 4

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.

ADFR - ADC Free Running Select

#define ADFR 5

When this bit is set (one) the ADC operates in Free Running Mode. In this mode, the ADC samples and updates the data registers continuously. Clearing this bit (zero) will terminate Free Running Mode.

ADSC - ADC Start Conversion

#define ADSC 6

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 7

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 = $05;

ADC8 - ADC Data Register High Byte Bit 0

#define ADC8 0

ADC9 - ADC Data Register High Byte Bit 1

#define ADC9 1

ADCL - ADC Data Register Low Byte

sfrb ADCL = $04;

ADC0 - ADC Data Register Low Byte Bit 0

#define ADC0 0

ADC1 - ADC Data Register Low Byte Bit 1

#define ADC1 1

ADC2 - ADC Data Register Low Byte Bit 2

#define ADC2 2

ADC3 - ADC Data Register Low Byte Bit 3

#define ADC3 3

ADC4 - ADC Data Register Low Byte Bit 4

#define ADC4 4

ADC5 - ADC Data Register Low Byte Bit 5

#define ADC5 5

ADC6 - ADC Data Register Low Byte Bit 6

#define ADC6 6

ADC7 - ADC Data Register Low Byte Bit 7

#define ADC7 7

WATCHDOG

WDTCR - Watchdog Timer Control Register

sfrb WDTCR = $21;

WDP0 - Watch Dog Timer Prescaler bit 0

#define WDP0 0

WDP1 - Watch Dog Timer Prescaler bit 1

#define WDP1 1

WDP2 - Watch Dog Timer Prescaler bit 2

#define WDP2 2

WDE - Watch Dog Enable

#define WDE 3

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

WDTOE - RW

#define WDTOE 4

This bit must be set (one) when the WDE bit is cleared. Otherwise, the watchdog will not be disabled. Once set, hardware will clear this bit to zero after four clock cycles. Refer to the description of the WDE bit for a watchdog disable procedure.

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 = $1F;

EEAR8 - EEPROM Read/Write Access Bit 8

#define EEAR8 0

EEARL - EEPROM Address Register Low Byte

sfrb EEARL = $1E;

EEAR0 - EEPROM Read/Write Access Bit 0

#define EEAR0 0

EEAR1 - EEPROM Read/Write Access Bit 1

#define EEAR1 1

EEAR2 - EEPROM Read/Write Access Bit 2

#define EEAR2 2

EEAR3 - EEPROM Read/Write Access Bit 3

#define EEAR3 3

EEAR4 - EEPROM Read/Write Access Bit 4

#define EEAR4 4

EEAR5 - EEPROM Read/Write Access Bit 5

#define EEAR5 5

EEAR6 - EEPROM Read/Write Access Bit 6

#define EEAR6 6

EEAR7 - EEPROM Read/Write Access Bit 7

#define EEAR7 7

EEDR - EEPROM Data Register

sfrb EEDR = $1D;

EEDR0 - EEPROM Data Register bit 0

#define EEDR0 0

EEDR1 - EEPROM Data Register bit 1

#define EEDR1 1

EEDR2 - EEPROM Data Register bit 2

#define EEDR2 2

EEDR3 - EEPROM Data Register bit 3

#define EEDR3 3

EEDR4 - EEPROM Data Register bit 4

#define EEDR4 4

EEDR5 - EEPROM Data Register bit 5

#define EEDR5 5

EEDR6 - EEPROM Data Register bit 6

#define EEDR6 6

EEDR7 - EEPROM Data Register bit 7

#define EEDR7 7

EECR - EEPROM Control Register

sfrb EECR = $1C;

EERE - EEPROM Read Enable

#define EERE 0

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 1

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 2

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 3

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.

CPU

SREG - Status Register

sfrb SREG = $3F;

SPH - Stack Pointer High

sfrb SPH = $3E;

SP8 - Stack pointer bit 8

#define SP8 0

SP9 - Stack pointer bit 9

#define SP9 1

SPL - Stack Pointer Low

sfrb SPL = $3D;

SP0 - Stack pointer bit 0

#define SP0 0

SP1 - Stack pointer bit 1

#define SP1 1

SP2 - Stack pointer bit 2

#define SP2 2

SP3 - Stack pointer bit 3

#define SP3 3

SP4 - Stack pointer bit 4

#define SP4 4

SP5 - Stack pointer bit 5

#define SP5 5

SP6 - Stack pointer bit 6

#define SP6 6

SP7 - Stack pointer bit 7

#define SP7 7

MCUCR - MCU Control Register

sfrb MCUCR = $35;

ISC00 - Interrupt Sense Control 0 bit 0

#define ISC00 0

ISC01 - Interrupt Sense Control 0 bit 1

#define ISC01 1

ISC10 - Interrupt Sense Control 1 bit 0

#define ISC10 2

ISC11 - Interrupt Sense Control 1 bit 1

#define ISC11 3

SM0 - Sleep Mode Select 0

#define SM0 4

SM1 and SM0 selects between different sleep modes. Please refer to the manual for further details.

SM1 - Sleep Mode Select 1

#define SM1 5

SM1 and SM0 selects between different sleep modes. Please refer to the manual for further details.

SE - Sleep Enable

#define SE 6

The SE bit must be set (one) to make the MCU enter the sleep mode when the SLEEP instruction is executed. To avoid the MCU entering the sleep mode unless it is the programmers purpose, it is recommended to set the Sleep Enable SE bit just before the execution of the SLEEP instruction.

MCUSR -

sfrb MCUSR = $34;

PORF - Power-on Reset Flag

#define PORF 0

EXTRF - External Reset Flag

#define EXTRF 1

EXTERNAL INTERRUPT

GIMSK - General Interrupt Mask Register

sfrb GIMSK = $3B;

INT0 - External Interrupt Request 0 Enable

#define INT0 6

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 MCU general Control Register (MCUCR) defines whether the external interrupt is activated on rising 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 program memory address $001. See also ?External Interrupts.? ? Bits 5..0 - Res: Reserved bits

INT1 - External Interrupt Request 1 Enable

#define INT1 7

When the INT1 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 Control1 bits 1/0 (ISC11 and ISC10) in the MCU general Control Register (MCUCR) defines whether the external interrupt is activated on rising or falling edge of the INT1 pin or level sensed. Activity on the pin will cause an interrupt request even if INT1 is configured as an output. The corresponding interrupt of External Interrupt Request 1 is executed from program memory address $002. See also ?External Interrupts?.

GIFR - General Interrupt Flag register

sfrb GIFR = $3A;

INTF0 - External Interrupt Flag 0

#define INTF0 6

When an event on the INT0 pin triggers an interrupt request, INTF0 becomes set (one). If the I-bit in SREG and the INT0 bit in GIMSK are set (one), the MCU will jump to the interrupt vector at address $001. The flag is cleared when the interrupt routine is executed. Alternatively, the flag can be cleared by writing a logical one to it.

INTF1 - External Interrupt Flag 1

#define INTF1 7

When an event on the INT1 pin triggers an interrupt request, INTF1 becomes set (one). If the I-bit in SREG and the INT1 bit in GIMSK are set (one), the MCU will jump to the interrupt vector at address $002. The flag is cleared when the interrupt routine is executed. Alternatively, the flag can be cleared by writing a logical one to it.