Table 92. Status Codes for Slave Receiver Mode
Status Code
(TWSR)
Prescaler Bits
are 0
Application Software Response
Status of the Two-wire Serial Bus
and Two-wire Serial Interface
Hardware
To TWCR
STA
To/from TWDR
STO
0
TWINT
1
TWEA
0
Next Action Taken by TWI Hardware
0x60
0x68
0x70
0x78
Own SLA+W has been received;
ACK has been returned
No TWDR action or
X
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
No TWDR action
X
X
0
0
1
1
1
0
Arbitration lost in SLA+R/W as No TWDR action or
master; own SLA+W has been
received; ACK has been returned
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
No TWDR action
X
X
0
0
1
1
1
0
General call address has been
received; ACK has been returned
No TWDR action or
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
No TWDR action
X
X
0
0
1
1
1
0
Arbitration lost in SLA+R/W as No TWDR action or
master; General call address has
Data byte will be received and NOT ACK will be
returned
been received; ACK has been
returned
No TWDR action
X
X
0
0
1
1
1
0
Data byte will be received and ACK will be returned
0x80
0x88
Previously addressed with own Read data byte or
SLA+W; data has been received;
Data byte will be received and NOT ACK will be
returned
ACK has been returned
Read data byte
X
0
0
0
1
1
1
0
Data byte will be received and ACK will be returned
Previously addressed with own Read data byte or
SLA+W; data has been received;
NOT ACK has been returned
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
Read data byte or
0
1
0
0
1
1
1
0
Read data byte or
Read data byte
1
0
0
1
1
1
0
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
0x90
0x98
Previously addressed with
general call; data has been re-
ceived; ACK has been returned
Read data byte or
X
Data byte will be received and NOT ACK will be
returned
Read data byte
X
0
0
0
1
1
1
0
Data byte will be received and ACK will be returned
Previously addressed with
general call; data has been
received; NOT ACK has been
returned
Read data byte or
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
Read data byte or
Read data byte or
0
1
0
0
1
1
1
0
Read data byte
1
0
1
1
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
0xA0
A
STOP condition or repeated Read data byte or
0
0
0
0
1
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;
START condition has been
received while still addressed as Read data byte or
slave
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
Read data byte or
1
1
0
0
1
1
0
1
Read data byte
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
222
AT90CAN128
4250E–CAN–12/04
ATMEL [ ATMEL ]
