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Transmission while transmitter is busy

If a task or function wants to transmit a CAN frame by calling the function CanBusWrite() while the configured CAN transmitter is busy, the following steps will be performed:

CAN transmission while transmitter is busy

  • The function CanBusWrite() is pending on the counting semaphore with the configured TxTimeout. The timeout must be set with CanBusIoCtl() CANBUS_SET_TX_TIMEOUT
  • If the function has the semaphore within the timeout, the given CAN frame is copied to the internal transmission queue. If a timeout error was detected, the function CanBusWrite() exits with an error-code.

    • Asynchronous to this actions, the transmission complete interrupt of the CAN controller shall activate the function CanBusTxHandler():

  • The interrupt handler checks if a CAN frame is in the internal transmission queue.
  • If a CAN frame is in the queue, the low level device driver function Write() is used to pass the CAN frame to the CAN controller.
  • The counting semaphore will be posted and the handler will be finished.
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