R01UH0823EJ0100 Rev.1.00
Page 1293 of 1823
Jul 31, 2019
RX23W Group
36. CAN Module (RSCAN)
Figure 36.28
Transmit Buffer Transmission Timing Chart (Transmit Abort Completed)
(1) When the TMCa.TMTR bit (a = 0 to 3) is set to 1 while the CAN bus is idle, the transmit priority determination
processing starts to determine the highest-priority transmit buffer. If transmit buffer a is determined to be the
highest-priority transmit buffer, the corresponding TMSTSa.TMTSTS flag becomes 1 (transmission is in progress)
and the CAN channel starts transmitting data.
(2) When it is determined that the transmit buffer is used for the next transmission or transmission is in progress,
message transmission is not aborted unless an error or arbitration lost occurs even if the TMCa.TMTAR bit is set to
1 (transmit abort is requested).
(3) The priority determination starts with the CRC delimiter for the next transmission. In this timing chart, buffer b is
not selected as the next transmit buffer.
(4) When transmit completes successfully, the TMSTSa.TMTRF[1:0] flags become 11b (transmission has been
completed (with transmit abort request)), the TMSTSa.TMTSTS flag and the TMCa.TMTR bit become 0, and the
TMTCSTS.TMTCSTSa flag becomes 1.
When the TMIEC.TMIEa value is 1 (transmit buffer interrupt is enabled), a transmit interrupt request is generated.
(1)
(2)
(4)
01b
00b
00b
SOF
Determine next
transmit priority
Determine next
transmit priority
EOF
SOF
CRC delimiter EOF
INT
00b
a = 0 to 3, b = 0 to 3
TMTR, TMTAR: Bits in the TMCa or TMCb register
TMTSTS, TMTRF[1:0]: Flags in the TMSTSa or TMSTSb register
TMTCSTSa, TMTCSTSb: Flags in the TMTCSTS register
TMTASTSa, TMTASTSb: Flags in the TMTASTS register
INT
High
Low
11b
[Transmit buffer a]
Example of transmission from transmit buffers a and b
1
0
1
0
CAN bus
TMTR bit
TMTAR bit
TMTSTS flag
TMTRF[1:0] flags
TMTCSTSa flag
Determine next
transmit priority
(3)
(5)
(6)
1
0
1
0
TMTASTSa flag
1
0
[Transmit buffer b]
1
0
1
0
TMTR bit
TMTAR bit
TMTSTS flag
TMTRF[1:0] flags
TMTCSTSb flag
1
0
1
0
TMTASTSb flag
1
0
CRC delimiter