RL78/D1A User's Manual: Hardware - Renesas

Under development
Preliminary document
Specifications in this document are tentative and subject to change.
RL78/D1A CHAPTER 14 CAN CONTROLLER
Caution If only two CAN nodes are connected to the CAN bus and one of them is operating in the receiveonly
mode, there is no ACK on the CAN bus. Due to the missing ACK, the transmitting node will
transmit an active error flag, and repeat transmitting a message frame. The transmitting node
becomes error passive after transmitting the message frame 16 times (assuming that the error
counter was 0 in the beginning and no other errors have occurred). After the message frame for
the 17th time is transmitted, the transmitting node generates a passive error flag. The receiving
node in the receive-only mode detects the first valid message frame at this point, and the VALID bit
is set to 1 for the first time.
14.13.2 Single-shot mode
In the single-shot mode, automatic re-transmission as defined in the CAN protocol is switched off (According to the
CAN protocol, a message frame transmission that has been aborted by either arbitration loss or error occurrence has to
be repeated without control by software.). All other behavior of single shot mode is identical to normal operation mode.
Features of single shot mode can not be used in combination with normal mode with ABT.
The single-shot mode disables the re-transmission of an aborted message frame transmission according to the setting
of the AL bit of the C0CTRL register. When the AL bit is cleared to 0, re-transmission upon arbitration loss and upon error
occurrence is disabled. If the AL bit is set to 1, re-transmission upon error occurrence is disabled, but re-transmission
upon arbitration loss is enabled. As a consequence, the TRQ bit in a message buffer defined as a transmit message
buffer is cleared to 0 by the following events.
- Successful transmission of the message frame
- Arbitration loss while sending the message frame
- Error occurrence while sending the message frame
The events arbitration loss and error occurrence can be distinguished by checking the CINTS4 and CINTS3 bits of the
C0INTS register respectively, and the type of the error can be identified by reading the LEC[2:0] bits of the C0LEC register.
Upon successful transmission of the message frame, the transmit completion interrupt bit CINTS0 of the C0INTS
register is set to 1. If the CIE0 bit of the C0IE register is set to 1 at this time, an interrupt request signal is output.
The single-shot mode can be used when emulating time-triggered communication methods (e.g. TTCAN level 1).
Caution The AL bit is only valid in Single-shot mode. It does not influence the operation of re-transmission
upon arbitration loss in the other operation modes.
R01UH0317EJ0004 Rev. 0.04 906
Feb. 22, 2013