Datasheet

220
2490R–AVR–02/2013
ATmega64(L)
running as normal. Observe that if the AVR is set up with a long start-up time, the SCL line may
be held low for a long time, blocking other data transmissions.
Note that the Two-wire Serial Interface Data Register – TWDR does not reflect the last byte
present on the bus when waking up from these Sleep modes.
Table 90. Status Codes for Slave Receiver Mode
Status Code
(TWSR)
Prescaler Bits
Are 0
Status of the Two-wire Serial Bus
and Two-wire Serial Interface
Hardware
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
returned
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
returned
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
returned
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
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
returned
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
returned
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
general call; data has been re-
ceived; 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
returned
Data byte will be received and ACK will be returned
0x98 Previously addressed with
general 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
received 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