Datasheet

SAM9G20
DS60001516A-page 422  2017 Microchip Technology Inc.
Figure 30-20: Programmer Sends Data While the Bus is Busy
Figure 30-21: Arbitration Cases
The flowchart shown in Figure 30-22 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