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 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:.PP

                (_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