60.5.5.7 Transmit Cancellation

The MCAN supports transmit cancellation. This feature is especially intended for gateway applications and AUTOSAR-based applications. To cancel a requested transmission from a dedicated Tx Buffer or a Tx Queue Buffer, the processor has to write a ‘1’ to the corresponding bit position (=number of Tx Buffer) of register MCAN_TXBCR. Transmit cancellation is not intended for Tx FIFO operation.

Successful cancellation is signalled by setting the corresponding bit of register MCAN_TXBCF to ‘1’.

In case a transmit cancellation is requested while a transmission from a Tx Buffer is already ongoing, the corresponding TXBRP bit remains set as long as the transmission is in progress. If the transmission was successful, the corresponding MCAN_TXBTO and MCAN_TXBCF bits are set. If the transmission was not successful, it is not repeated and only the corresponding MCAN_TXBCF bit is set.

Note: In case a pending transmission is cancelled immediately before this transmission could have been started, there follows a short time window where no transmission is started even if another message is also pending in this node. This may enable another node to transmit a message which may have a lower priority than the second message in this node.