Texas Instruments MSP430x4xx Family, User Manual

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USCI Operation: I2C Mode
21-16 Universal Serial Communication Interface, I2C Mode
Figure 21−12 illustrates the I
2
C master transmitter operation.
Figure 21−12. I
2
C Master Transmitter Mode
Other master continues
S SLA/W
A
DATA
A
P
Successful
transmission to a
slave receiver
UCBxTXIFG= 1
DATA DATA
A A
UCTXSTP= 1
UCBxTXIFG=0
Next transfer started
with a repeated start
condition
DATA
A
S SLA/W
1) UCTR= 1(Transmitter)
2) UCTXSTT= 1
DATA
A
S SLA/R
1) UCTR= 0(Receiver)
2) UCTXSTT= 1
3) UCBxTXIFG= 0
Not acknowledge
received after slave
address
P
S SLA/W
S SLA/R
UCTXSTP= 1
1) UCTR= 1(Transmitter)
2) UCTXSTT= 1
1) UCTR= 0(Receiver)
2) UCTXSTT= 1
Arbitration lost in
slave address or
data byte
A
A
Other master continues
Arbitration lost and
addressed as slave
Other master continues
A
UCALIFG= 1
UCMST= 0
UCTR= 0(Receiver)
UCSTTIFG= 1
(UCGC= 1if general call)
UCBxTXIFG= 0
UCSTPIFG= 0
USCI continues as Slave Receiver
Not acknowledge
received after a data
byte
UCTXSTT= 0
UCTXSTP= 0
UCTXSTP= 0
UCALIFG= 1
UCMST= 0
(UCSTTIFG= 0)
Bus stalled (SCL held low)
until data available
Write data to UCBxTXBUF
1) UCTR= 1(Transmitter)
2) UCTXSTT= 1
UCBxTXIFG= 1
UCBxTXBUF discarded
UCTXSTT= 0
UCNACKIFG= 1
UCBxTXIFG= 0
UCBxTXBUF discarded
UCBxTXIFG= 1
UCBxTXBUF discarded
UCNACKIFG= 1
UCBxTXIFG= 0
UCBxTXBUF discarded
UCALIFG= 1
UCMST= 0
(UCSTTIFG= 0)