This documentation was generated automatically from the AVR Studio part description file `ATmega48.pdf`.

## 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

### UDR0 - USART I/O Data Register

`sfrb UDR0 = 0xC6;`

##### UDR0-0 - USART I/O Data Register bit 0

`#define UDR0-0_BIT 0`

`#define UDR0-0_MASK 1`

##### UDR0-1 - USART I/O Data Register bit 1

`#define UDR0-1_BIT 1`

`#define UDR0-1_MASK 2`

##### UDR0-2 - USART I/O Data Register bit 2

`#define UDR0-2_BIT 2`

`#define UDR0-2_MASK 4`

##### UDR0-3 - USART I/O Data Register bit 3

`#define UDR0-3_BIT 3`

`#define UDR0-3_MASK 8`

##### UDR0-4 - USART I/O Data Register bit 4

`#define UDR0-4_BIT 4`

`#define UDR0-4_MASK 16`

##### UDR0-5 - USART I/O Data Register bit 5

`#define UDR0-5_BIT 5`

`#define UDR0-5_MASK 32`

##### UDR0-6 - USART I/O Data Register bit 6

`#define UDR0-6_BIT 6`

`#define UDR0-6_MASK 64`

##### UDR0-7 - USART I/O Data Register bit 7

`#define UDR0-7_BIT 7`

`#define UDR0-7_MASK 128`

### UCSR0A - USART Control and Status Register A

`sfrb UCSR0A = 0xC0;`

##### MPCM0 - Multi-processor Communication Mode

`#define MPCM0_BIT 0`

`#define MPCM0_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.

##### U2X0 - Double the USART transmission speed

`#define U2X0_BIT 1`

`#define U2X0_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.

##### UPE0 - Parity Error

`#define UPE0_BIT 2`

`#define UPE0_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.

##### DOR0 - Data overRun

`#define DOR0_BIT 3`

`#define DOR0_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.

##### FE0 - Framing Error

`#define FE0_BIT 4`

`#define FE0_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.

##### UDRE0 - USART Data Register Empty

`#define UDRE0_BIT 5`

`#define UDRE0_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 re

##### TXC0 - USART Transmitt Complete

`#define TXC0_BIT 6`

`#define TXC0_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

##### RXC0 - USART Receive Complete

`#define RXC0_BIT 7`

`#define RXC0_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.

### UCSR0B - USART Control and Status Register B

`sfrb UCSR0B = 0xC1;`

##### TXB80 - Transmit Data Bit 8

`#define TXB80_BIT 0`

`#define TXB80_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.

##### RXB80 - Receive Data Bit 8

`#define RXB80_BIT 1`

`#define RXB80_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.

##### UCSZ02 - Character Size

`#define UCSZ02_BIT 2`

`#define UCSZ02_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.

##### TXEN0 - Transmitter Enable

`#define TXEN0_BIT 3`

`#define TXEN0_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.

##### RXEN0 - Receiver Enable

`#define RXEN0_BIT 4`

`#define RXEN0_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.

##### UDRIE0 - USART Data register Empty Interrupt Enable

`#define UDRIE0_BIT 5`

`#define UDRIE0_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.

##### TXCIE0 - TX Complete Interrupt Enable

`#define TXCIE0_BIT 6`

`#define TXCIE0_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.

##### RXCIE0 - RX Complete Interrupt Enable

`#define RXCIE0_BIT 7`

`#define RXCIE0_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.

### UCSR0C - USART Control and Status Register C

`sfrb UCSR0C = 0xC2;`

##### UCPOL0 - Clock Polarity

`#define UCPOL0_BIT 0`

`#define UCPOL0_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).

##### UCSZ00 - Character Size

`#define UCSZ00_BIT 1`

`#define UCSZ00_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.

##### UCSZ01 - Character Size

`#define UCSZ01_BIT 2`

`#define UCSZ01_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.

##### USBS0 - Stop Bit Select

`#define USBS0_BIT 3`

`#define USBS0_MASK 8`

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

##### UPM00 - Parity Mode Bit 0

`#define UPM00_BIT 4`

`#define UPM00_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.

##### UPM01 - Parity Mode Bit 1

`#define UPM01_BIT 5`

`#define UPM01_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.

##### UMSEL00 - USART Mode Select

`#define UMSEL00_BIT 6`

`#define UMSEL00_MASK 64`

##### UMSEL01 - USART Mode Select

`#define UMSEL01_BIT 7`

`#define UMSEL01_MASK 128`

### UBRR0H - USART Baud Rate Register High Byte

`sfrb UBRR0H = 0xC5;`

##### 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`

### UBRR0L - USART Baud Rate Register Low Byte

`sfrb UBRR0L = 0xC4;`

##### 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`

## TWI

TWI: Simple yet powerful and flexible communications interface, only two bus lines needed. Both master and slave operation supported. Device can operate as transmitter or receiver. 7-bit address space allows up to 128 different slave addresses. Multi-master arbitration support Up to 400 kHz data transfer speed Slew-rate limited output drivers Noise suppression circuitry rejects spikes on bus lines Fully programmable slave address with general call support Address recognition causes wake-up when AVR is in sleep mode The Two-Wire Serial Interface (TWI) is ideally suited to typical microcontroller applications. The TWI protocol allows the systems designer to interconnect up to 128 different devices using only two bidirectional bus lines, one for clock (SCL) andone for data (SDA). The only external hardware needed to implement the bus is a single pull-up resistor for each of the TWI bus lines. All devices connected to the bus have individual addresses, and mechanisms for resolving bus contention are inherent in the TWI pr

### TWAMR - TWI (Slave) Address Mask Register

`sfrb TWAMR = 0xBD;`

##### TWAM0

`#define TWAM0_BIT 1`

`#define TWAM0_MASK 2`

##### TWAM1

`#define TWAM1_BIT 2`

`#define TWAM1_MASK 4`

##### TWAM2

`#define TWAM2_BIT 3`

`#define TWAM2_MASK 8`

##### TWAM3

`#define TWAM3_BIT 4`

`#define TWAM3_MASK 16`

##### TWAM4

`#define TWAM4_BIT 5`

`#define TWAM4_MASK 32`

##### TWAM5

`#define TWAM5_BIT 6`

`#define TWAM5_MASK 64`

##### TWAM6

`#define TWAM6_BIT 7`

`#define TWAM6_MASK 128`

### TWBR - TWI Bit Rate register

`sfrb TWBR = 0xB8;`

##### TWBR0

`#define TWBR0_BIT 0`

`#define TWBR0_MASK 1`

##### TWBR1

`#define TWBR1_BIT 1`

`#define TWBR1_MASK 2`

##### TWBR2

`#define TWBR2_BIT 2`

`#define TWBR2_MASK 4`

##### TWBR3

`#define TWBR3_BIT 3`

`#define TWBR3_MASK 8`

##### TWBR4

`#define TWBR4_BIT 4`

`#define TWBR4_MASK 16`

##### TWBR5

`#define TWBR5_BIT 5`

`#define TWBR5_MASK 32`

##### TWBR6

`#define TWBR6_BIT 6`

`#define TWBR6_MASK 64`

##### TWBR7

`#define TWBR7_BIT 7`

`#define TWBR7_MASK 128`

### TWCR - TWI Control Register

`sfrb TWCR = 0xBC;`

##### TWIE - TWI Interrupt Enable

`#define TWIE_BIT 0`

`#define TWIE_MASK 1`

When this bit is written to one, and the I-bit in SREG is set, the TWI interrupt request will be activated for as long as the TWINT flag is high.

##### TWEN - TWI Enable Bit

`#define TWEN_BIT 2`

`#define TWEN_MASK 4`

The TWEN bit enables TWI operation and activates the TWI interface. When TWEN is written to one, the TWI takes control over the I/O pins connected to the SCL and SDA pins, enabling the slew-rate limiters and spike filters. If this bit is written to zero, the TWI is switched off and all TWI transmissions are terminated, regardless of any ongoing operation.

##### TWWC - TWI Write Collition Flag

`#define TWWC_BIT 3`

`#define TWWC_MASK 8`

The TWWC bit is set when attempting to write to the TWI Data Register - TWDR when TWINT is low. This flag is cleared by writing the TWDR register when TWINT is high.

##### TWSTO - TWI Stop Condition Bit

`#define TWSTO_BIT 4`

`#define TWSTO_MASK 16`

Writing the TWSTO bit to one in master mode will generate a STOP condition on the 2-wire Serial Bus. When the STOP condition is executed on the bus, the TWSTO bit is cleared automatically. In slave mode, setting the TWSTO bit can be used to recover from an error condition. This will not generate a STOP condition, but the TWI returns to a well-defined unaddressed slave mode and releases the SCL and SDA lines to a high impedance state.

##### TWSTA - TWI Start Condition Bit

`#define TWSTA_BIT 5`

`#define TWSTA_MASK 32`

The application writes the TWSTA bit to one when it desires to become a master on the 2-wire Serial Bus. The TWI hard-ware checks if the bus is available, and generates a START condition on the bus if it is free. However, if the bus is not free, the TWI waits until a STOP condition is detected, and then generates a new START condition to claim the bus Master sta-tus. TWSTA is cleared by the TWI hardware when the START condition has been transmitted.

##### TWEA - TWI Enable Acknowledge Bit

`#define TWEA_BIT 6`

`#define TWEA_MASK 64`

The TWEA bit controls the generation of the acknowledge pulse. If the TWEA bit is written to one, the ACK pulse is gener-ated on the TWI bus if the following conditions are met: 1. The device?s own slave address has been received. 2. A general call has been received, while the TWGCE bit in the TWAR is set. 3. A data byte has been received in master receiver or slave receiver mode. By writing the TWEA bit to zero, the device can be virtually disconnected from the 2-wire Serial Bus temporarily. Address recognition can then be resumed by writing the TWEA bit to one again

##### TWINT - TWI Interrupt Flag

`#define TWINT_BIT 7`

`#define TWINT_MASK 128`

This bit is set by hardware when the TWI has finished its current job and expects application software response. If the I-bit in SREG and TWIE in TWCR are set, the MCU will jump to the TWI interrupt vector. While the TWINT flag is set, the SCL low period is stretched. The TWINT flag must be cleared by software by writing a logic one to it. Note that this flag is not automatically cleared by hardware when executing the interrupt routine. Also note that clearing this flag starts the operation of the TWI, so all accesses to the TWI Address Register (TWAR), TWI Status Register (TWSR), and TWI Data Register (TWDR) must be complete before clearing this flag

### TWSR - TWI Status Register

`sfrb TWSR = 0xB9;`

##### TWPS0 - TWI Prescaler

`#define TWPS0_BIT 0`

`#define TWPS0_MASK 1`

Bits 1..0: These bits can be read and written, and control the bit rate prescaler. See ?Bit Rate Generator Unit? on page 165 for calculating bit rates.

##### TWPS1 - TWI Prescaler

`#define TWPS1_BIT 1`

`#define TWPS1_MASK 2`

Bits 1..0: These bits can be read and written, and control the bit rate prescaler. See ?Bit Rate Generator Unit? on page 165 for calculating bit rates.

##### TWS3 - TWI Status

`#define TWS3_BIT 3`

`#define TWS3_MASK 8`

Bits 7..3: These 5 bits reflect the status of the TWI logic and the 2-Wire Serial Bus. The different status codes are described later in this chapter. Note that the value read from TWSR contains both the 5-bit status value and the 2-bit prescaler value. The application designer should consider masking the prescaler bits to zero when checking the Status bits. This makes status checking independent of prescaler setting. This approach is used in this datasheet, unless otherwise noted. If the prescaler setting remains unchanged in the application, the prescaler bits need not be masked. Instead, bit 1:0 in the values that TWSR is compared to can be modified to match the prescaler setting. This will yield more efficient co

##### TWS4 - TWI Status

`#define TWS4_BIT 4`

`#define TWS4_MASK 16`

Bits 7..3: These 5 bits reflect the status of the TWI logic and the 2-Wire Serial Bus. The different status codes are described later in this chapter. Note that the value read from TWSR contains both the 5-bit status value and the 2-bit prescaler value. The application designer should consider masking the prescaler bits to zero when checking the Status bits. This makes status checking independent of prescaler setting. This approach is used in this datasheet, unless otherwise noted. If the prescaler setting remains unchanged in the application, the prescaler bits need not be masked. Instead, bit 1:0 in the values that TWSR is compared to can be modified to match the prescaler setting. This will yield more efficient co

##### TWS5 - TWI Status

`#define TWS5_BIT 5`

`#define TWS5_MASK 32`

Bits 7..3: These 5 bits reflect the status of the TWI logic and the 2-Wire Serial Bus. The different status codes are described later in this chapter. Note that the value read from TWSR contains both the 5-bit status value and the 2-bit prescaler value. The application designer should consider masking the prescaler bits to zero when checking the Status bits. This makes status checking independent of prescaler setting. This approach is used in this datasheet, unless otherwise noted. If the prescaler setting remains unchanged in the application, the prescaler bits need not be masked. Instead, bit 1:0 in the values that TWSR is compared to can be modified to match the prescaler setting. This will yield more efficient c

##### TWS6 - TWI Status

`#define TWS6_BIT 6`

`#define TWS6_MASK 64`

Bits 7..3: These 5 bits reflect the status of the TWI logic and the 2-Wire Serial Bus. The different status codes are described later in this chapter. Note that the value read from TWSR contains both the 5-bit status value and the 2-bit prescaler value. The application designer should consider masking the prescaler bits to zero when checking the Status bits. This makes status checking independent of prescaler setting. This approach is used in this datasheet, unless otherwise noted. If the prescaler setting remains unchanged in the application, the prescaler bits need not be masked. Instead, bit 1:0 in the values that TWSR is compared to can be modified to match the prescaler setting. This will yield more efficient co

##### TWS7 - TWI Status

`#define TWS7_BIT 7`

`#define TWS7_MASK 128`

Bits 7..3: These 5 bits reflect the status of the TWI logic and the 2-Wire Serial Bus. The different status codes are described later in this chapter. Note that the value read from TWSR contains both the 5-bit status value and the 2-bit prescaler value. The application designer should consider masking the prescaler bits to zero when checking the Status bits. This makes status checking independent of prescaler setting. This approach is used in this datasheet, unless otherwise noted. If the prescaler setting remains unchanged in the application, the prescaler bits need not be masked. Instead, bit 1:0 in the values that TWSR is compared to can be modified to match the prescaler setting. This will yield more efficient c

### TWDR - TWI Data register

`sfrb TWDR = 0xBB;`

##### TWD0 - TWI Data Register Bit 0

`#define TWD0_BIT 0`

`#define TWD0_MASK 1`

##### TWD1 - TWI Data Register Bit 1

`#define TWD1_BIT 1`

`#define TWD1_MASK 2`

##### TWD2 - TWI Data Register Bit 2

`#define TWD2_BIT 2`

`#define TWD2_MASK 4`

##### TWD3 - TWI Data Register Bit 3

`#define TWD3_BIT 3`

`#define TWD3_MASK 8`

##### TWD4 - TWI Data Register Bit 4

`#define TWD4_BIT 4`

`#define TWD4_MASK 16`

##### TWD5 - TWI Data Register Bit 5

`#define TWD5_BIT 5`

`#define TWD5_MASK 32`

##### TWD6 - TWI Data Register Bit 6

`#define TWD6_BIT 6`

`#define TWD6_MASK 64`

##### TWD7 - TWI Data Register Bit 7

`#define TWD7_BIT 7`

`#define TWD7_MASK 128`

### TWAR - TWI (Slave) Address register

`sfrb TWAR = 0xBA;`

##### TWGCE - TWI General Call Recognition Enable Bit

`#define TWGCE_BIT 0`

`#define TWGCE_MASK 1`

##### TWA0 - TWI (Slave) Address register Bit 0

`#define TWA0_BIT 1`

`#define TWA0_MASK 2`

##### TWA1 - TWI (Slave) Address register Bit 1

`#define TWA1_BIT 2`

`#define TWA1_MASK 4`

##### TWA2 - TWI (Slave) Address register Bit 2

`#define TWA2_BIT 3`

`#define TWA2_MASK 8`

##### TWA3 - TWI (Slave) Address register Bit 3

`#define TWA3_BIT 4`

`#define TWA3_MASK 16`

##### TWA4 - TWI (Slave) Address register Bit 4

`#define TWA4_BIT 5`

`#define TWA4_MASK 32`

##### TWA5 - TWI (Slave) Address register Bit 5

`#define TWA5_BIT 6`

`#define TWA5_MASK 64`

##### TWA6 - TWI (Slave) Address register Bit 6

`#define TWA6_BIT 7`

`#define TWA6_MASK 128`

## TIMER COUNTER 1

### TIMSK1 - Timer/Counter Interrupt Mask Register

`sfrb TIMSK1 = 0x6F;`

##### 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 CompareA 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 CompareB 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/Counter Interrupt Flag register

`sfrb TIFR1 = 0x16;`

##### 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.

### TCCR1A - Timer/Counter1 Control Register A

`sfrb TCCR1A = 0x80;`

##### 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 - Comparet Ouput 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 = 0x81;`

##### 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/Counter1 Control Register C

`sfrb TCCR1C = 0x82;`

##### FOC1B

`#define FOC1B_BIT 6`

`#define FOC1B_MASK 64`

##### FOC1A

`#define FOC1A_BIT 7`

`#define FOC1A_MASK 128`

### TCNT1H - Timer/Counter1 High Byte

`sfrb TCNT1H = 0x85;`

##### 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 = 0x84;`

##### 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 High Byte

`sfrb OCR1AH = 0x89;`

##### 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 Low Byte

`sfrb OCR1AL = 0x88;`

##### 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 High Byte

`sfrb OCR1BH = 0x8B;`

##### 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 Low Byte

`sfrb OCR1BL = 0x8A;`

##### 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 = 0x87;`

##### 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 = 0x86;`

##### 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`

### GTCCR - General Timer/Counter Control Register

`sfrb GTCCR = 0x23;`

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

`#define PSRSYNC_BIT 0`

`#define PSRSYNC_MASK 1`

When this bit is one, Timer/Counter1 and Timer/Counter0 prescaler will be Reset. This bit is normally cleared immediately by hardware, except if the TSM bit is set. Note that Timer/Counter1 and Timer/Counter0 share the same prescaler and a reset of this prescaler will affect both timers.

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

`#define TSM_BIT 7`

`#define TSM_MASK 128`

Writing the TSM bit to one activates the Timer/Counter Synchronization mode. In this mode, the value that is written to the PSR2 and PSR10 bits is kept, hence keeping the corresponding prescaler reset signals asserted. This ensures that the corresponding Timer/Counters are halted and can be configured to the same value without the risk of one of them advancing during configuration. When the TSM bit is written to zero, the PSR2 and PSR10 bits are cleared by hardware, and the Timer/Counters start counting simultaneous

## 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

### TIMSK2 - Timer/Counter Interrupt Mask register

`sfrb TIMSK2 = 0x70;`

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

`#define TOIE2_BIT 0`

`#define TOIE2_MASK 1`

When the TOIE2 bit is written to one and the I-bit in the Status Register is set (one), the Timer/Counter2 Overflow interrupt is enabled. The corresponding interrupt is executed if an overflow in Timer/Counter2 occurs, i.e., when the TOV2 bit is set in the Timer/Counter2 Interrupt Flag Register ? TIFR2.

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

`#define OCIE2A_BIT 1`

`#define OCIE2A_MASK 2`

When the OCIE2A bit is written to one and the I-bit in the Status Register is set (one), the Timer/Counter2 Compare Match A interrupt is enabled. The corresponding interrupt is executed if a compare match in Timer/Counter2 occurs, i.e., when the OCF2A bit is set in the Timer/Counter 2 Interrupt Flag Register ? TIFR2.

##### OCIE2B - Timer/Counter2 Output Compare Match B Interrupt Enable

`#define OCIE2B_BIT 2`

`#define OCIE2B_MASK 4`

When the OCIE2B bit is written to one and the I-bit in the Status Register is set (one), the Timer/Counter2 Compare Match B interrupt is enabled. The corresponding interrupt is executed if a compare match in Timer/Counter2 occurs, i.e., when the OCF2B bit is set in the Timer/Counter 2 Interrupt Flag Register ? TIFR2.

### TIFR2 - Timer/Counter Interrupt Flag Register

`sfrb TIFR2 = 0x17;`

##### 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, TOIE2A (Timer/Counter2 Overflow Interrupt Enable), and TOV2 are set (one), the Timer/Counter2 Overflow interrupt is executed. In PWM mode, this bit is set when Timer/Counter2 changes counting direction at 0x00.

##### OCF2A - Output Compare Flag 2A

`#define OCF2A_BIT 1`

`#define OCF2A_MASK 2`

The OCF2A bit is set (one) when a compare match occurs between the Timer/Counter2 and the data in OCR2A ? Output Compare Register2. OCF2A is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, OCF2A is cleared by writing a logic one to the flag. When the I-bit in SREG, OCIE2A (Timer/Counter2 Compare match Interrupt Enable), and OCF2A are set (one), the Timer/Counter2 Compare match Interrupt is executed.

##### OCF2B - Output Compare Flag 2B

`#define OCF2B_BIT 2`

`#define OCF2B_MASK 4`

The OCF2B bit is set (one) when a compare match occurs between the Timer/Counter2 and the data in OCR2B ? Output Compare Register2. OCF2B is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, OCF2B is cleared by writing a logic one to the flag. When the I-bit in SREG, OCIE2B (Timer/Counter2 Compare match Interrupt Enable), and OCF2B are set (one), the Timer/Counter2 Compare match Interrupt is executed.

### TCCR2A - Timer/Counter2 Control Register A

`sfrb TCCR2A = 0xB0;`

##### WGM20 - Waveform Genration Mode

`#define WGM20_BIT 0`

`#define WGM20_MASK 1`

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.

##### WGM21 - Waveform Genration Mode

`#define WGM21_BIT 1`

`#define WGM21_MASK 2`

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.

##### COM2B0 - Compare Output Mode bit 0

`#define COM2B0_BIT 4`

`#define COM2B0_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 functio

##### COM2B1 - Compare Output Mode bit 1

`#define COM2B1_BIT 5`

`#define COM2B1_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

##### COM2A0 - Compare Output Mode bit 1

`#define COM2A0_BIT 6`

`#define COM2A0_MASK 64`

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 7`

`#define COM2A1_MASK 128`

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

### TCCR2B - Timer/Counter2 Control Register B

`sfrb TCCR2B = 0xB1;`

##### 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.

##### WGM22 - Waveform Generation Mode

`#define WGM22_BIT 3`

`#define WGM22_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.

##### FOC2B - Force Output Compare B

`#define FOC2B_BIT 6`

`#define FOC2B_MASK 64`

Writing a logical one to this bit, forces a change in the compare match output pin PD7 (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 mode

##### 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 PD7 (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 mode

### TCNT2 - Timer/Counter2

`sfrb TCNT2 = 0xB2;`

##### 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`

### OCR2B - Timer/Counter2 Output Compare Register B

`sfrb OCR2B = 0xB4;`

##### OCR2-0 - Timer/Counter2 Output Compare Register Bit 0

`#define OCR2-0_BIT 0`

`#define OCR2-0_MASK 1`

##### OCR2-1 - Timer/Counter2 Output Compare Register Bit 1

`#define OCR2-1_BIT 1`

`#define OCR2-1_MASK 2`

##### OCR2-2 - Timer/Counter2 Output Compare Register Bit 2

`#define OCR2-2_BIT 2`

`#define OCR2-2_MASK 4`

##### OCR2-3 - Timer/Counter2 Output Compare Register Bit 3

`#define OCR2-3_BIT 3`

`#define OCR2-3_MASK 8`

##### OCR2-4 - Timer/Counter2 Output Compare Register Bit 4

`#define OCR2-4_BIT 4`

`#define OCR2-4_MASK 16`

##### OCR2-5 - Timer/Counter2 Output Compare Register Bit 5

`#define OCR2-5_BIT 5`

`#define OCR2-5_MASK 32`

##### OCR2-6 - Timer/Counter2 Output Compare Register Bit 6

`#define OCR2-6_BIT 6`

`#define OCR2-6_MASK 64`

##### OCR2-7 - Timer/Counter2 Output Compare Register Bit 7

`#define OCR2-7_BIT 7`

`#define OCR2-7_MASK 128`

### OCR2A - Timer/Counter2 Output Compare Register A

`sfrb OCR2A = 0xB3;`

##### OCR2-0 - Timer/Counter2 Output Compare Register Bit 0

`#define OCR2-0_BIT 0`

`#define OCR2-0_MASK 1`

##### OCR2-1 - Timer/Counter2 Output Compare Register Bit 1

`#define OCR2-1_BIT 1`

`#define OCR2-1_MASK 2`

##### OCR2-2 - Timer/Counter2 Output Compare Register Bit 2

`#define OCR2-2_BIT 2`

`#define OCR2-2_MASK 4`

##### OCR2-3 - Timer/Counter2 Output Compare Register Bit 3

`#define OCR2-3_BIT 3`

`#define OCR2-3_MASK 8`

##### OCR2-4 - Timer/Counter2 Output Compare Register Bit 4

`#define OCR2-4_BIT 4`

`#define OCR2-4_MASK 16`

##### OCR2-5 - Timer/Counter2 Output Compare Register Bit 5

`#define OCR2-5_BIT 5`

`#define OCR2-5_MASK 32`

##### OCR2-6 - Timer/Counter2 Output Compare Register Bit 6

`#define OCR2-6_BIT 6`

`#define OCR2-6_MASK 64`

##### OCR2-7 - Timer/Counter2 Output Compare Register Bit 7

`#define OCR2-7_BIT 7`

`#define OCR2-7_MASK 128`

### ASSR - Asynchronous Status Register

`sfrb ASSR = 0xB6;`

##### TCR2BUB - Timer/Counter Control Register2 Update Busy

`#define TCR2BUB_BIT 0`

`#define TCR2BUB_MASK 1`

When Timer/Counter2 operates asynchronously and TCCR2B is written, this bit becomes set. When TCCR2B has been updated from the temporary storage register, this bit is cleared by hardware. A logical zero in this bit indicates that TCCR2B is ready to be updated with a new value.

##### TCR2AUB - Timer/Counter Control Register2 Update Busy

`#define TCR2AUB_BIT 1`

`#define TCR2AUB_MASK 2`

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.

##### OCR2BUB - Output Compare Register 2 Update Busy

`#define OCR2BUB_BIT 2`

`#define OCR2BUB_MASK 4`

When Timer/Counter2 operates asynchronously and OCR2B is written, this bit becomes set. When OCR2B has been updated from the temporary storage register, this bit is cleared by hardware. A logical zero in this bit indicates that OCR2B is ready to be updated with a new value.

##### OCR2AUB - Output Compare Register2 Update Busy

`#define OCR2AUB_BIT 3`

`#define OCR2AUB_MASK 8`

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 - Timer/Counter2 Update Busy

`#define TCN2UB_BIT 4`

`#define TCN2UB_MASK 16`

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 - Asynchronous Timer/Counter2

`#define AS2_BIT 5`

`#define AS2_MASK 32`

When AS2 is written to zero, Timer/Counter2 is clocked from the I/O clock, clkI/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, OCR2B, TCCR2A and TCCR2B might be corrupted.

##### EXCLK - Enable External Clock Input

`#define EXCLK_BIT 6`

`#define EXCLK_MASK 64`

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.

### GTCCR - General Timer Counter Control register

`sfrb GTCCR = 0x23;`

##### PSRASY - Prescaler Reset Timer/Counter2

`#define PSRASY_BIT 1`

`#define PSRASY_MASK 2`

When this bit is one, the Timer/Counter2 prescaler will be reset. This bit is normally cleared immediately by hardware. If the bit is written when Timer/Counter2 is operating in asynchronous mode, the bit will remain one until the prescaler has been reset. The bit will not be cleared by hardware if the TSM bit is set. Refer to the description of the ?Bit 7 ? TSM: Timer/Counter Synchronization Mode? on page 107 for a description of the Timer/Counter Synchronization mode.

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

`#define TSM_BIT 7`

`#define TSM_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 No

### ADMUX - The ADC multiplexer Selection Register

`sfrb ADMUX = 0x7C;`

##### 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).

##### 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.

### ADCH - ADC Data Register High Byte

`sfrb ADCH = 0x79;`

##### 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 = 0x78;`

##### 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`

### ADCSRA - The ADC Control and Status register A

`sfrb ADCSRA = 0x7A;`

##### 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.

### ADCSRB - The ADC Control and Status register B

`sfrb ADCSRB = 0x7B;`

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

`#define ADTS0_BIT 0`

`#define ADTS0_MASK 1`

Please refer to table on page 240 in datasheet for trigger selection.

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

`#define ADTS1_BIT 1`

`#define ADTS1_MASK 2`

Please refer to table on page 240 in datasheet for trigger selection.

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

`#define ADTS2_BIT 2`

`#define ADTS2_MASK 4`

Please refer to table on page 240 in datasheet for trigger selection.

##### ACME

`#define ACME_BIT 6`

`#define ACME_MASK 64`

### DIDR0 - Digital Input Disable Register

`sfrb DIDR0 = 0x7E;`

##### ADC0D

`#define ADC0D_BIT 0`

`#define ADC0D_MASK 1`

##### ADC1D

`#define ADC1D_BIT 1`

`#define ADC1D_MASK 2`

##### ADC2D

`#define ADC2D_BIT 2`

`#define ADC2D_MASK 4`

##### ADC3D

`#define ADC3D_BIT 3`

`#define ADC3D_MASK 8`

##### ADC4D

`#define ADC4D_BIT 4`

`#define ADC4D_MASK 16`

##### ADC5D

`#define ADC5D_BIT 5`

`#define ADC5D_MASK 32`

## ANALOG COMPARATOR

### ACSR - Analog Comparator Control And Status Register

`sfrb ACSR = 0x30;`

##### 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

`#define ACIC_BIT 2`

`#define ACIC_MASK 4`

##### 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 = 0x7F;`

##### AIN0D - AIN0 Digital Input Disable

`#define AIN0D_BIT 0`

`#define AIN0D_MASK 1`

##### AIN1D - AIN1 Digital Input Disable

`#define AIN1D_BIT 1`

`#define AIN1D_MASK 2`

## PORTB

### PORTB - Port B Data Register

`sfrb PORTB = 0x05;`

##### 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 = 0x04;`

##### 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 = 0x03;`

##### 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 = 0x08;`

##### 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`

### DDRC - Port C Data Direction Register

`sfrb DDRC = 0x07;`

##### 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`

### PINC - Port C Input Pins

`sfrb PINC = 0x06;`

##### 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`

## PORTD

### PORTD - Port D Data Register

`sfrb PORTD = 0x0B;`

##### 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 = 0x0A;`

##### 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 = 0x09;`

##### 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`

## TIMER COUNTER 0

### OCR0B - Timer/Counter0 Output Compare Register

`sfrb OCR0B = 0x28;`

##### OCR0B_0

`#define OCR0B_0_BIT 0`

`#define OCR0B_0_MASK 1`

##### OCR0B_1

`#define OCR0B_1_BIT 1`

`#define OCR0B_1_MASK 2`

##### OCR0B_2

`#define OCR0B_2_BIT 2`

`#define OCR0B_2_MASK 4`

##### OCR0B_3

`#define OCR0B_3_BIT 3`

`#define OCR0B_3_MASK 8`

##### OCR0B_4

`#define OCR0B_4_BIT 4`

`#define OCR0B_4_MASK 16`

##### OCR0B_5

`#define OCR0B_5_BIT 5`

`#define OCR0B_5_MASK 32`

##### OCR0B_6

`#define OCR0B_6_BIT 6`

`#define OCR0B_6_MASK 64`

##### OCR0B_7

`#define OCR0B_7_BIT 7`

`#define OCR0B_7_MASK 128`

### OCR0A - Timer/Counter0 Output Compare Register

`sfrb OCR0A = 0x27;`

##### OCROA_0

`#define OCROA_0_BIT 0`

`#define OCROA_0_MASK 1`

##### OCROA_1

`#define OCROA_1_BIT 1`

`#define OCROA_1_MASK 2`

##### OCROA_2

`#define OCROA_2_BIT 2`

`#define OCROA_2_MASK 4`

##### OCROA_3

`#define OCROA_3_BIT 3`

`#define OCROA_3_MASK 8`

##### OCROA_4

`#define OCROA_4_BIT 4`

`#define OCROA_4_MASK 16`

##### OCROA_5

`#define OCROA_5_BIT 5`

`#define OCROA_5_MASK 32`

##### OCROA_6

`#define OCROA_6_BIT 6`

`#define OCROA_6_MASK 64`

##### OCROA_7

`#define OCROA_7_BIT 7`

`#define OCROA_7_MASK 128`

### TCNT0 - Timer/Counter0

`sfrb TCNT0 = 0x26;`

##### 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`

### TCCR0B - Timer/Counter Control Register B

`sfrb TCCR0B = 0x25;`

##### CS00 - Clock Select

`#define CS00_BIT 0`

`#define CS00_MASK 1`

##### CS01 - Clock Select

`#define CS01_BIT 1`

`#define CS01_MASK 2`

##### CS02 - Clock Select

`#define CS02_BIT 2`

`#define CS02_MASK 4`

##### WGM02

`#define WGM02_BIT 3`

`#define WGM02_MASK 8`

##### FOC0B - Force Output Compare B

`#define FOC0B_BIT 6`

`#define FOC0B_MASK 64`

##### FOC0A - Force Output Compare A

`#define FOC0A_BIT 7`

`#define FOC0A_MASK 128`

### TCCR0A - Timer/Counter Control Register A

`sfrb TCCR0A = 0x24;`

##### WGM00 - Waveform Generation Mode

`#define WGM00_BIT 0`

`#define WGM00_MASK 1`

##### WGM01 - Waveform Generation Mode

`#define WGM01_BIT 1`

`#define WGM01_MASK 2`

##### COM0B0 - Compare Output Mode, Fast PWm

`#define COM0B0_BIT 4`

`#define COM0B0_MASK 16`

##### COM0B1 - Compare Output Mode, Fast PWm

`#define COM0B1_BIT 5`

`#define COM0B1_MASK 32`

##### COM0A0 - Compare Output Mode, Phase Correct PWM Mode

`#define COM0A0_BIT 6`

`#define COM0A0_MASK 64`

##### COM0A1 - Compare Output Mode, Phase Correct PWM Mode

`#define COM0A1_BIT 7`

`#define COM0A1_MASK 128`

### TIMSK0 - Timer/Counter0 Interrupt Mask Register

`sfrb TIMSK0 = 0x6E;`

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

`#define TOIE0_BIT 0`

`#define TOIE0_MASK 1`

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

`#define OCIE0A_BIT 1`

`#define OCIE0A_MASK 2`

##### OCIE0B - Timer/Counter0 Output Compare Match B Interrupt Enable

`#define OCIE0B_BIT 2`

`#define OCIE0B_MASK 4`

### TIFR0 - Timer/Counter0 Interrupt Flag register

`sfrb TIFR0 = 0x15;`

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

`#define TOV0_BIT 0`

`#define TOV0_MASK 1`

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

`#define OCF0A_BIT 1`

`#define OCF0A_MASK 2`

##### OCF0B - Timer/Counter0 Output Compare Flag 0B

`#define OCF0B_BIT 2`

`#define OCF0B_MASK 4`

### GTCCR - General Timer/Counter Control Register

`sfrb GTCCR = 0x23;`

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

`#define PSRSYNC_BIT 0`

`#define PSRSYNC_MASK 1`

When this bit is one, Timer/Counter1 and Timer/Counter0 prescaler will be Reset. This bit is normally cleared immediately by hardware, except if the TSM bit is set. Note that Timer/Counter1 and Timer/Counter0 share the same prescaler and a reset of this prescaler will affect both timers.

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

`#define TSM_BIT 7`

`#define TSM_MASK 128`

Writing the TSM bit to one activates the Timer/Counter Synchronization mode. In this mode, the value that is written to the PSR2 and PSR10 bits is kept, hence keeping the corresponding prescaler reset signals asserted. This ensures that the corresponding Timer/Counters are halted and can be configured to the same value without the risk of one of them advancing during configuration. When the TSM bit is written to zero, the PSR2 and PSR10 bits are cleared by hardware, and the Timer/Counters start counting simultaneousl

## 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 = 0x69;`

##### 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.

##### ISC10 - External Interrupt Sense Control 1 Bit 0

`#define ISC10_BIT 2`

`#define ISC10_MASK 4`

The External Interrupt 1 is activated by the external pin INT1 if the SREG I-flag and the corresponding interrupt mask are set.The value on the INT1 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.

##### ISC11 - External Interrupt Sense Control 1 Bit 1

`#define ISC11_BIT 3`

`#define ISC11_MASK 8`

The External Interrupt 1 is activated by the external pin INT1 if the SREG I-flag and the corresponding interrupt mask are set.The value on the INT1 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 = 0x1D;`

##### 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.

##### INT1 - External Interrupt Request 1 Enable

`#define INT1_BIT 1`

`#define INT1_MASK 2`

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 External Interrupt Control Register A (EICRA)define whether the external interrupt is activated on rising and/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 the INT1 interrupt vector.

### EIFR - External Interrupt Flag Register

`sfrb EIFR = 0x1C;`

##### 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.

##### INTF1 - External Interrupt Flag 1

`#define INTF1_BIT 1`

`#define INTF1_MASK 2`

When an edge or logic change on the INT1 pin triggers an interrupt request,INTF1 becomes set (one).If the I-bit in SREG and the INT1 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.

### PCMSK2 - Pin Change Mask Register 2

`sfrb PCMSK2 = 0x6D;`

##### PCINT16 - Pin Change Enable Mask 16

`#define PCINT16_BIT 0`

`#define PCINT16_MASK 1`

##### PCINT17 - Pin Change Enable Mask 17

`#define PCINT17_BIT 1`

`#define PCINT17_MASK 2`

##### PCINT18 - Pin Change Enable Mask 18

`#define PCINT18_BIT 2`

`#define PCINT18_MASK 4`

##### PCINT19 - Pin Change Enable Mask 19

`#define PCINT19_BIT 3`

`#define PCINT19_MASK 8`

##### PCINT20 - Pin Change Enable Mask 20

`#define PCINT20_BIT 4`

`#define PCINT20_MASK 16`

##### PCINT21 - Pin Change Enable Mask 21

`#define PCINT21_BIT 5`

`#define PCINT21_MASK 32`

##### PCINT22 - Pin Change Enable Mask 22

`#define PCINT22_BIT 6`

`#define PCINT22_MASK 64`

##### PCINT23 - Pin Change Enable Mask 23

`#define PCINT23_BIT 7`

`#define PCINT23_MASK 128`

### PCMSK1 - Pin Change Mask Register 1

`sfrb PCMSK1 = 0x6C;`

##### 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`

### PCMSK0 - Pin Change Mask Register 0

`sfrb PCMSK0 = 0x6B;`

##### 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`

### PCIFR - Pin Change Interrupt Flag Register

`sfrb PCIFR = 0x1B;`

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

`#define PCIF0_BIT 0`

`#define PCIF0_MASK 1`

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 PCICR 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 1`

`#define PCIF1_MASK 2`

When a logic change on any PCINT14..8 pin triggers an interrupt request, PCIF1 becomes set (one). If the I-bit in SREG and the PCIE1 bit in PCICR 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.

##### PCIF2 - Pin Change Interrupt Flag 2

`#define PCIF2_BIT 2`

`#define PCIF2_MASK 4`

When a logic change on any PCINT23..16 pin triggers an interrupt request, PCIF2 becomes set (one). If the I-bit in SREG and the PCIE2 bit in PCICR 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.

## SPI

The Serial Peripheral Interface (SPI) allows high-speed synchronous data transfer between the device and peripheral devices or between several AVR devices. The SPI includes the following features: ? Full-duplex, 3-wire Synchronous Data Transfer ? Master or Slave Operation ? LSB First or MSB First Data Transfer ? Seven Programmable Bit Rates ? End of Transmission Interrupt Flag ? Write Collision Flag Protection ? Wake-up from Idle Mode ? Double Speed (CK/2) Master SPI Mode

### SPDR - SPI Data Register

`sfrb SPDR = 0x2E;`

##### 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`

### SPSR - SPI Status Register

`sfrb SPSR = 0x2D;`

##### 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 (see Table 71). 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 ck / 4 or lower. The SPI interface on the ATmega104 is also used for program memory and EEPROM downloading or uploading. See page 253 for serial programming and verification.

##### 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).

### SPCR - SPI Control Register

`sfrb SPCR = 0x2c;`

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

`#define SPR0_BIT 0`

`#define SPR0_MASK 1`

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

`#define SPR1_BIT 1`

`#define SPR1_MASK 2`

##### 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.

## CPU

### PCICR -

`sfrb PCICR = 0x68;`

##### PCIE0

`#define PCIE0_BIT 0`

`#define PCIE0_MASK 1`

##### PCIE1

`#define PCIE1_BIT 1`

`#define PCIE1_MASK 2`

##### PCIE2

`#define PCIE2_BIT 2`

`#define PCIE2_MASK 4`

### PRR - Power Reduction Register

`sfrb PRR = 0x64;`

##### 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`

##### PRTIM0 - Power Reduction Timer/Counter0

`#define PRTIM0_BIT 5`

`#define PRTIM0_MASK 32`

##### PRTIM2 - Power Reduction Timer/Counter2

`#define PRTIM2_BIT 6`

`#define PRTIM2_MASK 64`

##### PRTWI - Power Reduction TWI

`#define PRTWI_BIT 7`

`#define PRTWI_MASK 128`

### OSCCAL - Oscillator Calibration Value

`sfrb OSCCAL = 0x66;`

##### 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 = 0x61;`

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

`#define CLKPS0_BIT 0`

`#define CLKPS0_MASK 1`

These bits define the division factor between the selected clock source and the internal system clock. These bits can be written run-time to vary the clock frequency to suit the application requirements. As the divider divides the master clock input to the MCU, the speed of all synchronous peripherals is reduced when a division factor is used.

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

`#define CLKPS1_BIT 1`

`#define CLKPS1_MASK 2`

These bits define the division factor between the selected clock source and the internal system clock. These bits can be written run-time to vary the clock frequency to suit the application requirements. As the divider divides the master clock input to the MCU, the speed of all synchronous peripherals is reduced when a division factor is used.

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

`#define CLKPS2_BIT 2`

`#define CLKPS2_MASK 4`

These bits define the division factor between the selected clock source and the internal system clock. These bits can be written run-time to vary the clock frequency to suit the application requirements. As the divider divides the master clock input to the MCU, the speed of all synchronous peripherals is reduced when a division factor is used.

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

`#define CLKPS3_BIT 3`

`#define CLKPS3_MASK 8`

These bits define the division factor between the selected clock source and the internal system clock. These bits can be written run-time to vary the clock frequency to suit the application requirements. As the divider divides the master clock input to the MCU, the speed of all synchronous peripherals is reduced when a division factor is used.

##### CLKPCE - Clock Prescaler Change Enable

`#define CLKPCE_BIT 7`

`#define CLKPCE_MASK 128`

The CLKPCE bit must be written to logic one to enable change of the CLKPS bits. The CLKPCE bit is only updated when the other bits in CLKPR are simultaneously written to zero. CLKPCE is cleared by hardware four cycles after it is written or when CLKPS bits are written. Rewriting the CLKPCE bit within this time-out period does neither extend the time-out period, nor clear the CLKPCE bit.

### SREG - Status Register

`sfrb SREG = 0x3F;`

### SPH - Stack Pointer High

`sfrb SPH = 0x3E;`

##### 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`

### SPL - Stack Pointer Low

`sfrb SPL = 0x3D;`

##### 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`

### SPMCSR - Store Program Memory Control Register

`sfrb SPMCSR = 0x37;`

##### SELFPRGEN - Self Programming Enable

`#define SELFPRGEN_BIT 0`

`#define SELFPRGEN_MASK 1`

The explanation is to long to include here. Please refer to the printed documentation.

##### 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 executed 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.

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

`#define RWWSRE_BIT 4`

`#define RWWSRE_MASK 16`

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

`#define RWWSB_BIT 6`

`#define RWWSB_MASK 64`

##### 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.

### MCUCR - MCU Control Register

`sfrb MCUCR = 0x35;`

##### IVCE

`#define IVCE_BIT 0`

`#define IVCE_MASK 1`

##### PUD

`#define PUD_BIT 4`

`#define PUD_MASK 16`

### MCUSR - MCU Status Register

`sfrb MCUSR = 0x34;`

##### 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.

### SMCR -

`sfrb SMCR = 0x33;`

##### SE

`#define SE_BIT 0`

`#define SE_MASK 1`

##### SM0

`#define SM0_BIT 1`

`#define SM0_MASK 2`

##### SM1

`#define SM1_BIT 2`

`#define SM1_MASK 4`

##### SM2

`#define SM2_BIT 3`

`#define SM2_MASK 8`

### GPIOR2 - General Purpose I/O Register 2

`sfrb GPIOR2 = 0x2B;`

##### GPIOR20

`#define GPIOR20_BIT 0`

`#define GPIOR20_MASK 1`

##### GPIOR21

`#define GPIOR21_BIT 1`

`#define GPIOR21_MASK 2`

##### GPIOR22

`#define GPIOR22_BIT 2`

`#define GPIOR22_MASK 4`

##### GPIOR23

`#define GPIOR23_BIT 3`

`#define GPIOR23_MASK 8`

##### GPIOR24

`#define GPIOR24_BIT 4`

`#define GPIOR24_MASK 16`

##### GPIOR25

`#define GPIOR25_BIT 5`

`#define GPIOR25_MASK 32`

##### GPIOR26

`#define GPIOR26_BIT 6`

`#define GPIOR26_MASK 64`

##### GPIOR27

`#define GPIOR27_BIT 7`

`#define GPIOR27_MASK 128`

### GPIOR1 - General Purpose I/O Register 1

`sfrb GPIOR1 = 0x2A;`

##### GPIOR10

`#define GPIOR10_BIT 0`

`#define GPIOR10_MASK 1`

##### GPIOR11

`#define GPIOR11_BIT 1`

`#define GPIOR11_MASK 2`

##### GPIOR12

`#define GPIOR12_BIT 2`

`#define GPIOR12_MASK 4`

##### GPIOR13

`#define GPIOR13_BIT 3`

`#define GPIOR13_MASK 8`

##### GPIOR14

`#define GPIOR14_BIT 4`

`#define GPIOR14_MASK 16`

##### GPIOR15

`#define GPIOR15_BIT 5`

`#define GPIOR15_MASK 32`

##### GPIOR16

`#define GPIOR16_BIT 6`

`#define GPIOR16_MASK 64`

##### GPIOR17

`#define GPIOR17_BIT 7`

`#define GPIOR17_MASK 128`

### GPIOR0 - General Purpose I/O Register 0

`sfrb GPIOR0 = 0x1E;`

##### GPIOR00

`#define GPIOR00_BIT 0`

`#define GPIOR00_MASK 1`

##### GPIOR01

`#define GPIOR01_BIT 1`

`#define GPIOR01_MASK 2`

##### GPIOR02

`#define GPIOR02_BIT 2`

`#define GPIOR02_MASK 4`

##### GPIOR03

`#define GPIOR03_BIT 3`

`#define GPIOR03_MASK 8`

##### GPIOR04

`#define GPIOR04_BIT 4`

`#define GPIOR04_MASK 16`

##### GPIOR05

`#define GPIOR05_BIT 5`

`#define GPIOR05_MASK 32`

##### GPIOR06

`#define GPIOR06_BIT 6`

`#define GPIOR06_MASK 64`

##### GPIOR07

`#define GPIOR07_BIT 7`

`#define GPIOR07_MASK 128`

## WATCHDOG

### WDTCSR - Watchdog Timer Control Register

`sfrb WDTCSR = 0x60;`

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

`#define WDP0_BIT 0`

`#define WDP0_MASK 1`

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

`#define WDP1_BIT 1`

`#define WDP1_MASK 2`

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

`#define WDP2_BIT 2`

`#define WDP2_MASK 4`

##### 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`

##### WDP3 - Watchdog Timer Prescaler Bit 3

`#define WDP3_BIT 5`

`#define WDP3_MASK 32`

##### WDIE - Watchdog Timeout Interrupt Enable

`#define WDIE_BIT 6`

`#define WDIE_MASK 64`

##### WDIF - Watchdog Timeout Interrupt Flag

`#define WDIF_BIT 7`

`#define WDIF_MASK 128`

## 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

### EEARL - EEPROM Address Register Low Byte

`sfrb EEARL = 0x21;`

##### 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 = 0x20;`

##### 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 = 0x1F;`

##### 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

##### EEPE - EEPROM Write Enable

`#define EEPE_BIT 1`

`#define EEPE_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

##### EEMPE - EEPROM Master Write Enable

`#define EEMPE_BIT 2`

`#define EEMPE_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.

##### EEPM0 - EEPROM Programming Mode Bit 0

`#define EEPM0_BIT 4`

`#define EEPM0_MASK 16`

The EEPROM Programming mode bit setting defines which programming action that will be triggered when writing EEPE. It is possible to program data in one atomic operation (erase the old value and program the new value) or to split the Erase and Write operations in two different operations. The Programming times for the different modes are shown in Table 2. While EEPE is set, any write to EEPMn will be ignored. During reset, the EEPMn bits will be reset to 0b00 unless the EEPROM is busy programming.

##### EEPM1 - EEPROM Programming Mode Bit 1

`#define EEPM1_BIT 5`

`#define EEPM1_MASK 32`

The EEPROM Programming mode bit setting defines which programming action that will be triggered when writing EEPE. It is possible to program data in one atomic operation (erase the old value and program the new value) or to split the Erase and Write operations in two different operations. The Programming times for the different modes are shown in Table 2. While EEPE is set, any write to EEPMn will be ignored. During reset, the EEPMn bits will be reset to 0b00 unless the EEPROM is busy programming.