230
7530J–AVR–03/12
Atmel ATmega48/88/168 Automotive
Table 19-6.
Status Codes for Slave Transmitter Mode
Status
Code
(TWSR)
Prescal-
er Bits
are 0
Status of the 2-wire Seri-
al Bus and 2-wire Serial
Interface Hardware
Application Software Response
Next Action Taken by TWI Hardware
To/from
TWDR
To TWCR
ST
A
ST
O
TWI
NT
TW
EA
0xA8
Own SLA+R has been
received;
ACK has been returned
Load
data
byte or
Load
data
byte
X
0
1
0
1
Last data byte will be transmitted and
NOT ACK should be received
Data byte will be transmitted and ACK
should be received
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
0
1
0
1
Last data byte will be transmitted and
NOT ACK should be received
Data byte will be transmitted and ACK
should be received
0xB8
Data byte in TWDR has
been
transmitted;
ACK
has
been
received
Load
data
byte or
Load
data
byte
X
0
1
0
1
Last data byte will be transmitted and
NOT ACK should be received
Data byte will be transmitted and ACK
should be received
0xC0
Data byte in TWDR has
been
transmitted; NOT ACK
has been
received
No TWDR ac-
tion or
No TWDR ac-
tion or
No TWDR ac-
tion or
No TWDR ac-
tion
0
1
0
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 ac-
tion or
No TWDR ac-
tion or
No TWDR ac-
tion or
No TWDR ac-
tion
0
1
0
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