ATMEGA128RFA1_11 Datasheet, PDF (399/560 Pages) ATMEL Corporation – 8-bit Microcontroller with Low Power 2.4GHz Transceiver for ZigBee and IEEE 802.15.4

ATmega128RFA1
will then wake up from sleep and the TWI will hold the SCL clock will low during the
wake up and until the TWINT Flag is cleared (by writing it to one). Further data
transmission will be carried out as normal, with the AVR clocks 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 2-wire Serial Interface Data Register – TWDR does not reflect the last
byte present on the bus when waking up from these sleep modes.
Table 25-6. Status Code for Slave Transmitter Mode
Status Code
(TWSR)
Prescaler
Bits are 0
Status of the 2-wire
Serial Bus and 2-wire
Serial Interface
Hardware
Application Software Response
To TWCR
To/from TWDR ^{STA STD TWINT}
0xA8
Own SLA+R has been
Load data byte or
X
0
1
received; ACK has been
returned
Load data byte
X
0
1
0xB0
0xB8
Arbitration lost in SLA+R/W Load data byte or
X
0
1
as Master; own SLA+R has
been received; ACK has
Load data byte
X
0
1
been returned
Data byte in TWDR has
Load data byte or
X
0
1
been transmitted; ACK has
been received
Load data byte
X
0
1
0xC0
Data byte in TWDR has
No TWDR action or
0
0
1
been transmitted; NOT
ACK has been received
No TWDR action or
0
0
1
No TWDR action or
1
0
1
No TWDR action
1
0
1
0xC8
Last data byte in TWDR
No TWDR action or
0
0
1
has been transmitted
(TWEA = “0”); ACK has
No TWDR action or
0
0
1
been received
No TWDR action or
1
0
1
No TWDR action
1
0
1
TWEA
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Next Action Taken by TWI
Hardware
Last data byte will be transmitted and
NOT ACK should be received Data
byte will be transmitted and ACK
should be received
Last data byte will be transmitted and
NOT ACK should be received Data
byte will be transmitted and ACK
should be received
Last data byte will be transmitted and
NOT ACK should be received
Data byte will be transmitted and
ACK should be received
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
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
8266C-MCU Wireless-08/11
399