Datasheet

234
7593L–AVR–09/12
AT90USB64/128
Table 21-5. Status codes for Slave Receiver 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 TWINT TWEA
0x60 Own SLA+W has been received;
ACK has been returned
No TWDR action
or
No TWDR action
X
X
0
0
1
1
0
1
Data byte will be received and NOT ACK will be re-
turned
Data byte will be received and ACK will be returned
0x68 Arbitration lost in SLA+R/W as
Master; own SLA+W has been
received; ACK has been returned
No TWDR action
or
No TWDR action
X
X
0
0
1
1
0
1
Data byte will be received and NOT ACK will be re-
turned
Data byte will be received and ACK will be returned
0x70 General call address has been
received; ACK has been returned
No TWDR action
or
No TWDR action
X
X
0
0
1
1
0
1
Data byte will be received and NOT ACK will be re-
turned
Data byte will be received and ACK will be returned
0x78 Arbitration lost in SLA+R/W as
Master; General call address has
been received; ACK has been re-
turned
No TWDR action
or
No TWDR action
X
X
0
0
1
1
0
1
Data byte will be received and NOT ACK will be re-
turned
Data byte will be received and ACK will be returned
0x80 Previously addressed with own
SLA+W; data has been received;
ACK has been returned
Read data byte
or
Read data byte
X
X
0
0
1
1
0
1
Data byte will be received and NOT ACK will be re-
turned
Data byte will be received and ACK will be returned
0x88 Previously addressed with own
SLA+W; data has been received;
NOT ACK has been returned
Read data byte
or
Read data byte
or
Read data byte
or
Read data byte
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
0x90 Previously addressed with gener-
al call; data has been received;
ACK has been returned
Read data byte
or
Read data byte
X
X
0
0
1
1
0
1
Data byte will be received and NOT ACK will be re-
turned
Data byte will be received and ACK will be returned
0x98 Previously addressed with gener-
al call; data has been received;
NOT ACK has been returned
Read data byte
or
Read data byte
or
Read data byte
or
Read data byte
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
0xA0 A STOP condition or repeated
START condition has been re-
ceived while still addressed as
Slave
No 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