R01UH0823EJ0100 Rev.1.00
Page 1272 of 1823
Jul 31, 2019
RX23W Group
36. CAN Module (RSCAN)
36.5.2
Transmission Using Transmit Buffers
Setting the transmit request bit (TMCp.TMTR bit) in a transmit buffer to 1 (transmission is requested) allows
transmission of data frames or remote frames.
Transmit result is shown by the corresponding TMSTSp.TMTRF[1:0] flags. When transmit completes successfully, the
TMSTSp.TMTRF[1:0] flags become 10b (transmission has been completed (without transmit abort request)) or 11b
(transmission has been completed (with transmit abort request)).
(1) Transmit Abort Function
With respect to transmit buffers for which the TMSTSp.TMTRM flag is 1 (a transmit request is present), when the
TMCp.TMTAR bit is set to 1 (transmit abort is requested), the transmit request is canceled. When transmit abort is
completed, the TMSTSp.TMTRF[1:0] flags become 01b (transmit abort has been completed) and the transmit request is
canceled (the TMSTSp.TMTRM flag becomes 0).
A message that is being transmitted or a message to be transmitted next according to the transmit priority determination
cannot be aborted. However, when an arbitration lost or an error has occurred while a message for which the
TMCp.TMTAR bit is set to 1 is being transmitted, retransmission is not performed.
(2) One-Shot Transmission Function (Retransmission Disabling Function)
When the TMCp.TMOM bit is set to 1 (one-shot transmission is enabled), transmission is performed only once. Even if
an arbitration lost or an error occurs, retransmission is not performed.
One-shot transmit result is shown by the corresponding TMSTSp.TMTRF[1:0] flags. When one-shot transmit completes
successfully, the TMSTSp.TMTRF[1:0] flags become 10b or 11b. When an arbitration lost or an error has occurred, the
TMSTSp.TMTRF[1:0] flags become 01b (transmit abort has been completed).
36.5.3
Transmission Using FIFO Buffers
Messages of a volume of the FIFO buffer depth set by the CFCCL0.CFDC[2:0] bits can be stored in a single transmit/
receive FIFO buffer. Messages are transmitted sequentially on a first-in, first-out basis.
Transmit/receive FIFO buffers are linked to transmit buffers selected by the CFCCH0.CFTML[1:0] bits.
When the CFCCL0.CFE bit is set to 1 (transmit/receive FIFO buffers are used), transmit/receive FIFO buffers become
targets of transmit priority determination. Priority determination is made for only the message to be transmitted next in a
FIFO buffer.
When the CFCCL0.CFE bit is set to 0 (no transmit/receive FIFO buffer is used), the CFSTS0.CFEMP flag becomes 1
(the transmit/receive FIFO buffer contains no message (buffer empty)) at the timing below.
The transmit/receive FIFO buffer becomes empty immediately when the message in it is not being transmitted or is
not to be transmitted next.
The transmit/receive FIFO buffer becomes empty after transmission completion, CAN bus error detection, or
arbitration lost when the message in it is being transmitted or to be transmitted next.
When the CFCCL0.CFE bit is set to 0, all messages in transmit/receive FIFO buffers are lost and messages cannot be
stored in FIFO buffers. Confirm that the CFSTS0.CFEMP flag becomes 1 before setting the CFCCL0.CFE bit to 1 again.
(1) Interval Transmission Function
To transmit messages from the same FIFO buffer while a transmit/receive FIFO buffer that is set to transmit mode is in
use, message transmission interval time can be set.
Immediately after the first message has been transmitted successfully from the FIFO buffer with the CFCCL0.CFE bit
set to 1, the interval timer starts counting (after EOF7 of the CAN protocol). After that, when the interval time has
passed, the next message is transmitted. The interval timer stops in channel reset mode or by setting the CFCCL0.CFE
bit to 0.
The interval time is set by the CFCCH0.CFITT[7:0] bits. When the interval timer is not used, set the