Rainbow Electronics ATmega128RFA1 - Manual (Page 390)

390
8266A-MCU Wireless-12/09
ATmega128RFA1
Table 25-3. Status codes for Master Transmitter 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
Hardware To/from TWDR STA STO TWINT TWEA
Next Action Taken by TWI
Hardware
0x08 A START condition has
been transmitted Load SLA+W 0 0 1 X SLA+W will be transmitted; ACK or
NOT ACK will be received
0x10 A repeated START
condition has been
transmitted Load SLA+W or
Load SLA+R
0
0
0
0
1
1
X
X
SLA+W will be transmitted; ACK or
NOT ACK will be received
SLA+R will be transmitted; Logic will
switch to Master Receiver mode
0x18 SLA+W has been
transmitted; ACK has
been received Load data byte o
No TWDR action or
No TWDR action or
No TWDR action 0
1
0
1
0
0
1
1
1
1
1
1
X
X
X
X
Data byte will be transmitted and
ACK or NOT ACK will be received
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
0x20 SLA+W has been
transmitted; NOT ACK
has been received Load data byte or
No TWDR action or
No TWDR action or
No TWDR action 0
1
0
1
0
0
1
1
1
1
1
1
X
X
X
X
Data byte will be transmitted and
ACK or NOT ACK will be received
Repeated START will be transmitted
STOP condition will be transmitted
and TWSTO Flag will be rese
STOP condition followed by a START
condition will be transmitted and
TWSTO Flag will be reset
0x28 Data byte has been
transmitted; ACK has
been received Load data byte or
No TWDR action or
No TWDR action or
No TWDR action 0
1
0
1
0
0
1
1
1
1
1
1
X
X
X
X
Data byte will be transmitted and
ACK or NOT ACK will be received
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
0x30 Data byte has been
transmitted; NOT ACK
has been received Load data byte or
No TWDR action or
No TWDR action or
No TWDR action 0
1
0
1
0
0
1
1
1
1
1
1
X
X
X
X
Data byte will be transmitted and
ACK or NOT ACK will be received
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
0x38 Arbitration lost in SLA+W
or data bytes 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 entered
A START condition will be
transmitted when the bus be-comes
free
25.7.2 Master Receiver Mode
In the Master Receiver mode, a number of data bytes are received from a Slave
Transmitter (for Slave see
Figure 25-13 on page 391). In order to enter a Master mode,
a START condition must be transmitted. The format of the following address packet
determines whether Master Transmitter or Master Receiver mode is to be entered. If
SLA+W is transmitted, MT mode is entered, if SLA+R is transmitted, MR mode is
entered. All the status codes mentioned in this section assume that the prescaler bits
are zero or are masked to zero.