Rainbow Electronics ATmega163L - Manual (Page 75)

ATmega163(L)
75
Table 32. Status Codes for Master Transmitter Mode
Status code
(TWSR)
Status of the 2-wire Serial Bus
and 2-wire Serial Interface
hardware
Application software response
Next action taken by 2-wire Serial Interface hardware
To/from TWDR
To TWCR
STA STO TWINT TWEA
$08 A START condition has been
transmitted
Load SLA+W X 0 1 X SLA+W will be transmitted;
ACK or NOT ACK will be received
$10 A repeated START condition
has been transmitted
Load SLA+W or
Load SLA+R
X
X
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
$18 SLA+W 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
$20 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 reset
STOP condition followed by a START condition will be
transmitted and TWSTO flag will be reset
$28 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
$30 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
$38 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