Atmel ATmega328P Xplained Mini MEGA328P-XMINI MEGA328P-XMINI Data Sheet
Product codes
MEGA328P-XMINI
222
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
Atmel-8271H-AVR- ATmega-Datasheet_08/2014
Table 22-3.
Status codes for Master Receiver Mode
Status Code
(TWSR)
Prescaler Bits
are 0
(TWSR)
Prescaler Bits
are 0
Status of the 2-wire Serial Bus
and 2-wire Serial Interface
Hardware
and 2-wire Serial Interface
Hardware
Application Software Response
Next Action Taken by TWI Hardware
To/from TWDR
To TWCR
STA
STO
TWIN
T
TWE
A
0x08
A START condition has been
transmitted
transmitted
Load SLA+R
0
0
1
X
SLA+R will be transmitted
ACK or NOT ACK will be received
ACK or NOT ACK will be received
0x10
A repeated START condition
has been transmitted
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 NOT ACK will be received
SLA+W will be transmitted
Logic will switch to Master Transmitter mode
ACK or NOT ACK 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
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
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
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
returned
Data byte will be received and ACK will be returned
0x48
SLA+R has been transmitted;
NOT ACK has been received
NOT ACK has been received
No TWDR action or
No TWDR action or
No TWDR action or
No TWDR action
1
0
0
1
0
1
1
1
1
1
1
1
X
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
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
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
returned
Data byte will be received and ACK will be returned
0x58
Data byte has been received;
NOT ACK has been returned
NOT ACK has been returned
Read data byte or
Read data byte or
Read data byte or
Read data byte
1
0
0
1
0
1
1
1
1
1
1
1
X
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
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