D. this is done by writing s, Table 25-4 on, Atmega128rfa1 – Rainbow Electronics ATmega128RFA1 User Manual
Page 392
392
8266A-MCU Wireless-12/09
ATmega128RFA1
START enables the Master to switch between Slaves, Master Transmitter mode and
Master Receiver mode without losing control over the bus.
Table 25-4. Status codes for Master Receiver Mode
Application Software Response
To TWCR
Status Code
(TWSR)
Prescaler
Bits are 0
Status of the 2-wire
Serial Bus and 2-wire
Serial Interface Hard-
ware
To/from TWDR
STA
STD
TWINT
TWEA
Next Action Taken by TWI
Hardware
0x08
A START condition has
been transmitted
Load SLA+R
0
0
1
X
SLA+R will be transmitted ACK or
NOT ACK will be received
0x10
A repeated START
condition has been
transmitted
Load SLA+R or
Load SLA+W
0
0
0
0
1
1
X
X
SLA+R will be transmitted ACK or
NOTACK will be received
SLA+W will be transmitted Logic will
switch to Master Transmitter mode
0x38
Arbitration lost in SLA+R
or NOT ACK bit
No TWDR action or
No TWDR action
0
1
0
0
1
1
X
X
2-wire Serial Bus will be released
and not addressed Slave mode will
be entered
A START condition will be
transmitted when the bus becomes
free
0x40
SLA+R has been
transmitted; ACK has
been received
No TWDR action or
No TWDR action
0
0
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
0x48
SLA+R has been
transmitted; NOT ACK
has been received
No TWDR action or
No TWDR action or
No TWDR action
1
0
1
0
1
1
1
1
1
X
X
X
Repeated START will be transmitted
STOP condition will be transmitted
and TWSTO Flag will be reset
STOP condition followed by a
START condition will be transmitted
and TWSTO Flag will be reset
0x50
Data byte has been
received; ACK has been
returned
Read data byte or
Read data byte
0
0
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
0x58
Data byte has been
received; NOT ACK has
been returned
Read data byte or
Read data byte or
Read data byte
1
0
1
0
1
1
1
1
1
X
X
X
Repeated START will be transmitted
STOP condition will be transmitted
and TWSTO Flag will be reset
STOP condition followed by a
START condition will be transmitted
and TWSTO Flag will be reset