Rainbow Electronics AT91CAP9S250A - Manual (Page 508)

508
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
34.9.5.7 Reversal after a Repeated Start
34.9.5.8 Reversal of Read to Write
The master initiates the communication by a read command and finishes it by a write command.
Figure 34-29 on page 508 describes the repeated start + reversal from Read to Write mode.
Figure 34-29. Repeated Start + Reversal from Read to Write Mode
1. TXCOMP is only set at the end of the transmission because after the repeated start, SADR is detected again.
34.9.5.9 Reversal of Write to Read
The master initiates the communication by a write command and finishes it by a read com-
mand.
Figure 34-30 on page 508 describes the repeated start + reversal from Write to Read
mode.
Figure 34-30. Repeated Start + Reversal from Write to Read Mode
Notes: 1. In this case, if TWI_THR has not been written at the end of the read command, the clock is automatically stretched before
the ACK.
2. TXCOMP is only set at the end of the transmission because after the repeated start, SADR is detected again.
S SADR R A DATA0 A DATA1 SADR RS NA W A DATA2 A DATA3 A P
Cleared after read
DATA0 DATA1
DATA2 DATA3
SVACC
SVREAD
TWD
TWI_THR
TWI_RHR
EOSACC
TXRDY
RXRDY
TXCOMP As soon as a START is detected
S SADR W A DATA0 A DATA1 SADR RS A R A DATA2 A DATA3 NA P
Cleared after read
DATA0
DATA2 DATA3
DATA1
TXCOMP
TXRDY
RXRDY
As soon as a START is detected
Read TWI_RHR
SVACC
SVREAD
TWD
TWI_RHR
TWI_THR
EOSACC