Datasheet

233
2545T–AVR–05/11
ATmega48/88/168
Table 22-5. Status codes for slave transmitter mode.
Status code
(TWSR)
prescaler bits
are 0
Status of the 2-wire serial bus
and 2-wire serial interface hard-
ware
Application software response
Next action taken by TWI hardware
To/from TWDR
To TWCR
STA STO TWIN
T
TWE
A
0xA8 Own SLA+R has been received;
ACK has been returned
Load data byte or
load data byte
X
X
0
0
1
1
0
1
Last data byte will be transmitted and NOT ACK should
be received
Data byte will be transmitted and ACK should be re-
ceived
0xB0 Arbitration lost in SLA+R/W as
Master; own SLA+R has been
received; ACK has been returned
Load data byte or
load data byte
X
X
0
0
1
1
0
1
Last data byte will be transmitted and NOT ACK should
be received
Data byte will be transmitted and ACK should be re-
ceived
0xB8 Data byte in TWDR has been
transmitted; ACK has been
received
Load data byte or
load data byte
X
X
0
0
1
1
0
1
Last data byte will be transmitted and NOT ACK should
be received
Data byte will be transmitted and ACK should be re-
ceived
0xC0 Data byte in TWDR has been
transmitted; NOT ACK has been
received
No TWDR action or
no TWDR action or
no TWDR action or
no TWDR action
0
0
1
1
0
0
0
0
1
1
1
1
0
1
0
1
Switched to the not addressed slave mode;
no recognition of own SLA or GCA
Switched to the not addressed slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
Switched to the not addressed slave mode;
no recognition of own SLA or GCA;
a START condition will be transmitted when the bus
becomes free
Switched to the not addressed slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”;
a START condition will be transmitted when the bus
becomes free
0xC8 Last data byte in TWDR has been
transmitted (TWEA = “0”); ACK
has been received
No TWDR action or
no TWDR action or
no TWDR action or
no TWDR action
0
0
1
1
0
0
0
0
1
1
1
1
0
1
0
1
Switched to the not addressed slave mode;
no recognition of own SLA or GCA
Switched to the not addressed slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
Switched to the not addressed slave mode;
no recognition of own SLA or GCA;
a START condition will be transmitted when the bus
becomes free
Switched to the not addressed slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”;
a START condition will be transmitted when the bus
becomes free