I'm using the callback which is passed the index of the transmitted mailbox when the status is kStatus_FLEXCAN_TxIdle. I could use this to keep track of which mailboxes are free when a new request comes in but is there an existing way to check if a TX mailbox is free?
Related to this: When the status is kStatus_FLEXCAN_ErrorStatus, the other parameter passed to the callback is the status bits not the mailbox index. If I attempt to transmit and it is NACK'd I expect to get an error. How do I recover the mailbox index that failed to transmit?