SH7760 Datasheet, PDF (864/1345 Pages) Renesas Technology Corp – SuperHTM RISC engine

22.6.3 Message Transmission Sequence
(1) Event Trigger Transmission
• Message Transmission Request
The following is an example to transmit a CAN frame onto the bus. Note that IRR8 is set
when one of the CANTXACK or CANABACK bits is set, meaning one of the Mailbox has
completed its transmission or transmission abortion and is now ready to be updated for the
next transmission, whereas the GSR3 means that there is currently no transmission request
made (CANTXPR = H'0000).
HCAN2 is in normal mode
(MBC=H'000 or H'001,
TTT=0)
Mailbox[˜] is ready
to be updated for
next transmission
Update message data of
Mailbox
Write a 1 to CANTXPR
at any desired time
Internal arbitration
No
in the highest priority?
Yes
Transmission start
Clear CANTXACK [˜]
Yes
No
CANTXACK [˜] set?
Yes
No
IRR8 set?
CAN bus
arbitration
End of frame
CAN bus
Figure 22.6 Transmission Request
Rev. 1.0, 02/03, page 814 of 1294