Each Tx Buffer has its own Transmission Request Pending bit.

The bits are reset after a requested transmission has completed or has been cancelled via register TXBCR.

TXBRP bits are set only for those Tx Buffers configured via TXBC. After a TXBRP bit has been set, a Tx scan is started to check for the pending Tx request with the highest priority (Tx Buffer with lowest Message ID).

A cancellation request resets the corresponding transmission request pending bit of register TXBRP. In case a transmission has already been started when a cancellation is requested, this is done at the end of the transmission, regardless whether the transmission was successful or not. The cancellation request bits are reset directly after the corresponding TXBRP bit has been reset.

After a cancellation has been requested, a finished cancellation is signaled via TXBCF

• after successful transmission together with the corresponding TXBTO bit
• when the transmission has not yet been started at the point of cancellation
• when the transmission has been aborted due to lost arbitration
• when an error occurred during frame transmission

In DAR mode all transmissions are automatically canceled if they are not successful. The corresponding TXBCF bit is set for all unsuccessful transmissions.