Renesas RH850 Series

RH850 Series CAN Transmit Procedure (CAN FD Mode)
R01AN6029EJ0100 Rev.1.0 Page
37
of 42
May 10, 2017
7. Transmit Data Padding (only in CAN FD mode)
If the payload length indicated by the DLC value of the set transmit message exceeds the payload storage area size of
the buffer used for transmission, the excess payload is padded with “CCH”.
This processing is performed when the transmit buffer merge mode is not enabled (the TMME bit of the CFG register
is “0”) and when the following cases occur.
・Transmit/receive FIFO set to transmit or gateway mode:
When the payload length of the transmit DLC exceeds the payload storage area size of the transmit/receive FIFO
set in the CFPLS [2: 0] bit of the CFCCk register.
・Transmit buffer (including the transmit queue):
When the payload length of the transmit DLC exceeds 20 bytes
When transmit buffer merge mode is enabled, transmit data padding is not performed for transmissions using the
transmit buffer, the transmit/receive FIFO buffer, or the transmit queue. At this time, do not set the DLC value of the
transmit message to a payload length that exceeds the payload storage size of the buffer used for transmission.