ATMEGA48P_10 Datasheet, PDF (233/420 Pages) ATMEL Corporation – 8-bit Microcontroller with 4/8/16K Bytes In-System Programmable Flash

ATmega48P/88P/168P
Table 21-4.
Status Code
(TWSR)
Prescaler Bits
are 0
0x60
0x68
0x70
0x78
0x80
0x88
Status Codes for Slave Receiver Mode
Status of the 2-wire Serial Bus
and 2-wire Serial Interface Hard-
ware
Own SLA+W has been received;
ACK has been returned
Arbitration lost in SLA+R/W as
Master; own SLA+W has been
received; ACK has been returned
General call address has been
received; ACK has been returned
Arbitration lost in SLA+R/W as
Master; General call address has
been received; ACK has been
returned
Previously addressed with own
SLA+W; data has been received;
ACK has been returned
Previously addressed with own
SLA+W; data has been received;
NOT ACK has been returned
Application Software Response
To/from TWDR
To TWCR
STA STO TWIN
T
No TWDR action or X
0
1
No TWDR action
X
0
1
No TWDR action or X
0
1
No TWDR action
X
0
1
No TWDR action or X
0
1
No TWDR action
X
0
1
No TWDR action or X
0
1
No TWDR action
X
0
1
Read data byte or
X
0
1
Read data byte
X
0
1
Read data byte or
0
0
1
Read data byte or
0
0
1
Read data byte or
1
0
1
Read data byte
1
0
1
0x90
0x98
Previously addressed with
Read data byte or
X
0
1
general call; data has been re-
ceived; ACK has been returned Read data byte
X
0
1
Previously addressed with
Read data byte or
0
0
1
general call; data has been
received; NOT ACK has been
Read data byte or
0
0
1
returned
Read data byte or
1
0
1
Read data byte
1
0
1
0xA0
A STOP condition or repeated
START condition has been
received while still addressed as
Slave
No action
0
0
1
0
0
1
1
0
1
1
0
1
TWE
A
0
1
0
1
0
1
0
1
Next Action Taken by TWI Hardware
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
0
Data byte will be received and NOT ACK will be
returned
1
Data byte will be received and ACK will be returned
0
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA
1
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
0
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
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
0
Data byte will be received and NOT ACK will be
returned
1
Data byte will be received and ACK will be returned
0
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA
1
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
0
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
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
0
Switched to the not addressed Slave mode;
no recognition of own SLA or GCA
1
Switched to the not addressed Slave mode;
own SLA will be recognized;
GCA will be recognized if TWGCE = “1”
0
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
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
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