Datasheet

V850ES/JG3-H, V850ES/JH3-H CHAPTER 20 CAN CONTROLLER
R01UH0042EJ0500 Rev.5.00 Page 990 of 1513
Aug 12, 2011
20.10 Message Transmission
20.10.1 Message transmission
In all the operation modes, if the C0MCTRLm.TRQ bit is set to 1 in a message buffer that satisfies the following
conditions, the message buffer that is to transmit a message is searched.
• Used as a message buffer
(C0MCONFm.MA0 bit set to 1.)
• Set as a transmit message buffer
(C0MCONFm.MT2 to C0MCONFm.MT0 bits set to 000B.)
• Ready for transmission
(C0MCTRLm.RDY bit is set to 1.)
Remark m = 00 to 31
The CAN system is a multi-master communication system. In a system like this, the priority of message transmission is
determined based on message identifiers (IDs). To facilitate transmission processing by software when there are several
messages awaiting transmission, the CAN module uses hardware to check the ID of the message with the highest priority
and automatically identifies that message. This eliminates the need for software-based priority control.
Transmission priority is controlled by the identifier (ID).
Figure 20-31. Message Processing Example
Message No.
The CAN module transmits messages in the following sequence.
Message waiting to be transmitted
ID = 120H
ID = 229H
ID = 223H
ID = 023H
ID = 123H
0
1
2
3
4
5
6
7
8
9
1. Message 6
2. Message 1
3. Message 8
4. Message 5
5. Message 2