BAT32G1x9 user manual | Chapter 22 CAN control
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Rev.1.02
Note: If only two CAN nodes are connected to the CAN bus and one of the nodes is running in
receive-only mode, there is no ACK on the CAN bus. Due to the lack of an ACK, the
transport node transmits the active error flag and sends the message frame repeatedly.
The transport node becomes a passive error after sending the message frame 16 times
(assuming that the error counter starts with 0 and no other errors occur). After the 17th
packet frame is transmitted, the transmission node generates a passive error flag. The
receive node in receive-only mode now detects the first valid message frame, and the
VALID bit is set to 1 for the first time.
22.13.2
Single-shot mode
In single-pass mode, the automatic retransmission defined in the CAN protocol is turned off (under the
CAN protocol, packet frame transmissions that are aborted due to loss of arbitration or the occurrence of an
error must be repeated (without software control)). All other behaviors in single-shot mode are the same as
in normal operating mode. Single-shot mode cannot be used with regular mode with ABT.
Single-pass mode disables retransmissions that abort packet frame transmissions based on the AL bit
setting of the CnCTRL register. When the AL bit is cleared to 0, the Arbitration is lost and the retransmission
is disabled when an error occurs. If the AL bit is set to 1, retransmission is disabled when an error occurs,
but retransmission is enabled when Arbitration is lost. Therefore, the following event is defined as a TRQ bit
in the packet buffer of the send packet buffer cleared to 0.
- The message frame was successfully sent
- Arbitration loss occurs for sending packet frames
- An error occurred while sending a message frame
By examining the CNNTS4 and CNTS3 bits of the CnINTS registers separately, it is possible to
distinguish between event arbitration losses and error occurrences, and the type of error can be identified by
reading the LEC [2:0] bit of the CnLEC register.
After the packet frame is successfully transmitted, the transmission of the CnINTS register completes
with the interrupt bit CINTS0 set to 1. If the CIE0 bit of the CnIE register is set to 1 at this point, an interrupt
request signal is output.
Single-pass mode can be used when simulating time-triggered communication methods such as
TTCAN level 1.
Note: The AL bit is only valid in single-shot mode. The retransmission operation does not affect
arbitrate losses in other operating modes.