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# <util/twi.h>: TWI bit mask definitions

## Detailed Description

     #include <util/twi.h>

This header file contains bit mask definitions for use with the AVR TWI interface.

## TWSR values

Mnemonics: TW_MT_xxx - master transmitter TW_MR_xxx - master receiver TW_ST_xxx - slave transmitter TW_SR_xxx - slave receiver
#define | TW_START 0x08
#define | TW_REP_START 0x10
#define | TW_MT_SLA_ACK 0x18
#define | TW_MT_SLA_NACK 0x20
#define | TW_MT_DATA_ACK 0x28
#define | TW_MT_DATA_NACK 0x30
#define | TW_MT_ARB_LOST 0x38
#define | TW_MR_ARB_LOST 0x38
#define | TW_MR_SLA_ACK 0x40
#define | TW_MR_SLA_NACK 0x48
#define | TW_MR_DATA_ACK 0x50
#define | TW_MR_DATA_NACK 0x58
#define | TW_ST_SLA_ACK 0xA8
#define | TW_ST_ARB_LOST_SLA_ACK 0xB0
#define | TW_ST_DATA_ACK 0xB8
#define | TW_ST_DATA_NACK 0xC0
#define | TW_ST_LAST_DATA 0xC8
#define | TW_SR_SLA_ACK 0x60
#define | TW_SR_ARB_LOST_SLA_ACK 0x68
#define | TW_SR_GCALL_ACK 0x70
#define | TW_SR_ARB_LOST_GCALL_ACK 0x78
#define | TW_SR_DATA_ACK 0x80
#define | TW_SR_DATA_NACK 0x88
#define | TW_SR_GCALL_DATA_ACK 0x90
#define | TW_SR_GCALL_DATA_NACK 0x98
#define | TW_SR_STOP 0xA0
#define | TW_NO_INFO 0xF8
#define | TW_BUS_ERROR 0x00
#define | TW_STATUS_MASK
#define | TW_STATUS (TWSR & TW_STATUS_MASK)

## R/~W bit in SLA+R/W address field.

#define | TW_READ 1
#define | TW_WRITE 0

## Define Documentation

#define TW_BUS_ERROR 0x00

illegal start or stop condition

#define TW_MR_ARB_LOST 0x38

arbitration lost in SLA+R or NACK

#define TW_MR_DATA_ACK 0x50

data received, ACK returned

#define TW_MR_DATA_NACK 0x58

data received, NACK returned

#define TW_MR_SLA_ACK 0x40

SLA+R transmitted, ACK received

#define TW_MR_SLA_NACK 0x48

SLA+R transmitted, NACK received

#define TW_MT_ARB_LOST 0x38

arbitration lost in SLA+W or data

#define TW_MT_DATA_ACK 0x28

data transmitted, ACK received

#define TW_MT_DATA_NACK 0x30

data transmitted, NACK received

#define TW_MT_SLA_ACK 0x18

SLA+W transmitted, ACK received

#define TW_MT_SLA_NACK 0x20

SLA+W transmitted, NACK received

#define TW_NO_INFO 0xF8

no state information available

#define TW_READ 1

SLA+R address

#define TW_REP_START 0x10

repeated start condition transmitted

#define TW_SR_ARB_LOST_GCALL_ACK 0x78

arbitration lost in SLA+RW, general call received, ACK returned

#define TW_SR_ARB_LOST_SLA_ACK 0x68

arbitration lost in SLA+RW, SLA+W received, ACK returned

#define TW_SR_DATA_ACK 0x80

data received, ACK returned

#define TW_SR_DATA_NACK 0x88

data received, NACK returned

#define TW_SR_GCALL_ACK 0x70

general call received, ACK returned

#define TW_SR_GCALL_DATA_ACK 0x90

general call data received, ACK returned

#define TW_SR_GCALL_DATA_NACK 0x98

general call data received, NACK returned

#define TW_SR_SLA_ACK 0x60

SLA+W received, ACK returned

#define TW_SR_STOP 0xA0

stop or repeated start condition received while selected

#define TW_ST_ARB_LOST_SLA_ACK 0xB0

arbitration lost in SLA+RW, SLA+R received, ACK returned

#define TW_ST_DATA_ACK 0xB8

data transmitted, ACK received

#define TW_ST_DATA_NACK 0xC0

data transmitted, NACK received

#define TW_ST_LAST_DATA 0xC8

last data byte transmitted, ACK received

#define TW_ST_SLA_ACK 0xA8

SLA+R received, ACK returned

#define TW_START 0x08

start condition transmitted

#define TW_STATUS (TWSR & TW_STATUS_MASK)

TWSR, masked by TW_STATUS_MASK

#define TW_STATUS_MASK

Value:

    (_BV(TWS7)|_BV(TWS6)|_BV(TWS5)|_BV(TWS4)|\
                                    _BV(TWS3))

The lower 3 bits of TWSR are reserved on the ATmega163. The 2 LSB carry the prescaler bits on the newer ATmegas.

#define TW_WRITE 0

SLA+W address

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