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AT32UC3B
Note that a STOP or a repeated START always follows a NACK.
19.13.4.2
Write Sequence
In the case of a Write sequence (SVREAD is low), the RXRDY (Receive Holding Register
Ready) flag is set as soon as a character has been received in the RHR (TWI Receive Holding
Register). RXRDY is reset when reading the RHR.
TWI continues receiving data until a STOP condition or a REPEATED_START + an address dif-
ferent from SADR is detected. Note that at the end of the write sequence TXCOMP flag is set
and SVACC reset.
19.13.4.3
Clock Synchronization Sequence
In the case where THR or RHR is not written/read in time, TWI performs a clock synchronization.
Clock stretching information is given by the SCLWS (Clock Wait state) bit.
19.13.4.4
General Call
In the case where a GENERAL CALL is performed, GACC (General Call ACCess) flag is set.
After GACC is set, it is up to the programmer to interpret the meaning of the GENERAL CALL
and to decode the new address programming sequence.
19.13.4.5
Peripheral DMA Controller
As it is impossible to know the exact number of data to receive/send, the use of Peripheral DMA
Controller is NOT recommended in SLAVE mode.
19.13.5
Data Transfer
19.13.5.1
Read Operation
The read mode is defined as a data requirement from the master.
After a START or a REPEATED START condition is detected, the decoding of the address
starts. If the slave address (SADR) is decoded, SVACC is set and SVREAD indicates the direc-
tion of the transfer.
Until a STOP or REPEATED START condition is detected, TWI continues sending data loaded
in the THR register.
If a STOP condition or a REPEATED START + an address different from SADR is detected,
SVACC is reset.