Datasheet

733
SAM3X / SAM3A [DATASHEET]
Atmel-11057C-ATARM-SAM3X-SAM3A-Datasheet_23-Mar-15
Figure 33-30. 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.
Reversal of Write to Read
The master initiates the communication by a write command and finishes it by a read command.Figure 33-31 on
page 733 describes the repeated start + reversal from Write to Read mode.
Figure 33-31. 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.
33.10.6 Read Write Flowcharts
The flowchart shown in Figure 33-32 on page 734 gives an example of read and write operations in Slave mode. A
polling or interrupt method can be used to check the status bits. The interrupt method requires that the interrupt
enable register (TWI_IER) be configured first.
SSADR R ADATA 0A DATA 1
SADRSr
NA
W A DATA2 A DATA 3 AP
Cleared after read
DATA 0 DATA 1
DATA 2 DATA3
SVACC
SVREAD
TWD
TWI_THR
TWI_RHR
EOSACC
TXRDY
RXRDY
TXCOMP
As soon as a START is detected
SSADR W ADATA 0A DATA1
SADRSr
A
R A DATA2 A DATA 3 NA P
Cleared after read
DATA 0
DATA 2 DATA 3
DATA 1
TXCOMP
TXRDY
RXRDY
As soon as a START is detected
Read TWI_RHR
SVACC
SVREAD
TWD
TWI_RHR
TWI_THR
EOSACC