Rainbow Electronics AT91CAP9S250A - Manual (Page 500)

500
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
7. If TWI has to be set in Slave mode, wait until TXCOMP flag is at 1 and then program the
Slave mode.
Note: In the case where the arbitration is lost and TWI is addressed, TWI will not acknowledge even if it
is programmed in Slave mode as soon as ARBLST is set to 1. Then, the Master must repeat
SADR.
Figure 34-20. Programmer Sends Data While the Bus is Busy
Figure 34-21. Arbitration Cases
The flowchart shown in Figure 34-22 on page 501 gives an example of read and write operations
in Multi-master mode.
TWCK
TWD DATA sent by a master
STOP sent by the master START sent by the TWI
DATA sent by the TWI
Bus is busy
Bus is free
A transfer is programmed
(DADR + W + START + Write THR)
Transfer is initiated
TWI DATA transfer
Transfer is kept
Bus is considered as free
TWCK
Bus is busy Bus is free
A transfer is programmed
(DADR + W + START + Write THR)
Transfer is initiated
TWI DATA transfer Transfer is kept
Bus is considered as free
Data from a Master
Data from TWI S 0
S 0 0
1
1
1
ARBLST
S 0
S 0 0
1
1
1
TWD S 0 0 1
1 1
1 1
Arbitration is lost
TWI stops sending data
P
S 0 1 P 0
1 1
1 1 Data from the master Data from the TWI
Arbitration is lost
The master stops sending data
Transfer is stopped
Transfer is programmed again
(DADR + W + START + Write THR)
TWCK
TWD