R01UH0823EJ0100 Rev.1.00
Page 1295 of 1823
Jul 31, 2019
RX23W Group
36. CAN Module (RSCAN)
Figure 36.30
Transmit/Receive FIFO Buffer Transmission Timing Chart (Transmission Completed
Successfully)
(1) While the CAN bus is idle, when the CFCCL0.CFE value is 1 (transmit/receive FIFO buffer 0 is used) and the
CFCCL0.CFDC[2:0] value is 001b (4 messages) or more and the CFSTS0.CFMC[5:0] value is 01h or more, the
priority determination processing starts to determine the highest-priority transmit message. When the highest-
priority transmit message has been determined, transmission of the message starts.
(2) When a transmit request from a buffer is present, the priority determination starts with the CRC delimiter for the
next transmission.
(3) When transmit completes successfully, the CFSTS0.CFMC[5:0] value is decremented. Setting the CFCCL0.CFIM
bit to 1 (a FIFO transmit interrupt request is generated each time a message has been transmitted) sets the
CFSTS0.CFTXIF flag to 1 (a transmit/receive FIFO transmit interrupt request is present).
(4) The CFSTS0.CFTXIF flag can be cleared by the program.
(5) Message transmission from transmit/receive FIFO buffer 0 has been completed and the CFSTS0.CFMC[5:0] value
is decremented. The CFSTS0.CFMC[5:0] flags become 00h and therefore the CFSTS0.CFEMP flag becomes 1 (the
transmit/receive FIFO buffer contains no message (buffer empty)).
Transmission is continued until the CFSTS0.CFEMP flag becomes 1. It is possible to continuously store transmit
messages in FIFO buffers until the CFSTS0.CFFLL flag becomes 1 (the transmit/receive FIFO buffer is full).
CFDC[2:0], CFE: Bits in the CFCCL0 register
CFMC[5:0], CFEMP, CFTXIF: Flags in the CFSTS0 register
Example of transmission from transmit/receive FIFO buffer 0
SOF
Determine next
transmit priority
Determine next
transmit priority
EOF
SOF
INT
CRC
delimiter
High
Low
[Transmit/receive FIFO buffer 0]
CAN bus
0
1
2
0
1
0
1
(1)
(2)
(3)
(4)
(5)
EOF
INT
CRC
delimiter
Determine next
transmit priority
CFDC[2:0] bits
CFE bit
CFMC[5:0] flags
CFEMP flag
CFTXIF flag
1
0
1
0
1
0