Datasheet

Status Code
(TWSR)
Prescaler
Bits are 0
Status of the 2-wire Serial
Bus and 2-wire Serial
Interface Hardware
Application Software Response Next Action Taken by TWI
Hardware
To/from
TWDR
To TWCRn
STA STO TWINT TWEA
0x28 Data byte has been
transmitted;
ACK has been received
Load data
byte or
0 0 1 X Data byte will be transmitted
and ACK or NOT ACK will be
received
No TWDR
action or
1 0 1 X Repeated START will be
transmitted
No TWDR
action or
0 1 1 X STOP condition will be
transmitted and TWSTO Flag
will be reset
No TWDR
action
1 1 1 X STOP condition followed by a
START condition will be
transmitted and TWSTO Flag
will be reset
0x30 Data byte has been
transmitted;
NOT ACK has been received
Load data
byte or
0 0 1 X Data byte will be transmitted
and ACK or NOT ACK will be
received
No TWDR
action or
1 0 1 X Repeated START will be
transmitted
No TWDR
action or
0 1 1 X STOP condition will be
transmitted and TWSTO Flag
will be reset
No TWDR
action
1 1 1 X STOP condition followed by a
START condition will be
transmitted and TWSTO Flag
will be reset
0x38 Arbitration lost in SLA+W or
data bytes
No TWDR
action or
0 0 1 X 2-wire Serial Bus will be
released and not addressed
Slave mode entered
No TWDR
action
1 0 1 X A START condition will be
transmitted when the bus
becomes free
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
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