Transmit Abort Function - Renesas M32R/ECU Series User Manual

13
(4) Completion of data frame transmission
When data frame transmission has finished, the CAN Message Slot Control Register's TRFIN (Transmit/
Receive Finished) bit and the CAN Slot Interrupt Request Status Register are set to "1". Also, a timestamp
count value at which transmission has finished is written to the CAN Message Slot Timestamp (C0MSLnTSP,
C1MSLnTSP), and the transmit operation is thereby completed.
If the CAN slot interrupt request has been enabled, an interrupt request is generated at
completion of transmit operation. The slot which has had transmission completed goes to an
inactive state and remains inactive (neither transmit nor receive) until it is newly set in software.
Bit arrangement in the CAN Message Slot Control Register
b0 (b8) 1 2 3
TR RR RM RL
0 0 0 0
Note 1: When in this state, data can be written to the message slot.
Figure 13.5.2 Operation of the CAN Message Slot Control Register during Data Frame Transmission

13.5.3 Transmit Abort Function

The transmit abort function is used to cancel a transmit request that has once been set. This is accomplished by
writing H'0F to the CAN Message Slot Control Register for the slot to be canceled. When transmit abort is
accepted, the CAN module clears the CAN Message Slot Control Register's TRSTAT (Transmit/Receive Sta-
tus) bit to "0", allowing for data to be written to the message slot. The following shows the conditions under which
transmit abort is accepted.
[Conditions]
• When the target message is waiting for transmission
• When a CAN bus error occurs during transmission
• When lost in CAN bus arbitration
4 5 6 b7(b15)
RA ML TRSTAT TRFIN
0 0 0 0
Transmission
aborted
B'0000 0010
B'0000 0001
(Note 1)
13.5 Transmitting Data Frames
B'0000 0000
(Note 1)
Write H'80
Transmission aborted
B'1000 0000
Transmit request
Lost in CAN bus arbitration
accepted
or a CAN bus error occurs
B'1000 0010
Transmission completed
B'1000 0001
13-80
CAN MODULE
Wait for transmission
32180 Group User's Manual (Rev.1.0)