The DMU signals to the attached DMA Controller (DMA request) when there is a newly received message available at one of the attached M_CAN's Rx FIFOs respectively when there is the possibility to load a new Tx message into the M_CAN's Tx FIFO/Queue.
The DMA controller then autonomously transfers the received message from the M_CAN's Message RAM to the System Memory or the message to be transmitted from the System Memory to the M_CAN's Message RAM.
After the DMA transfer has completed, the DMU acknowledges this to the M_CAN's Rx FIFO respectively sets the related M_CAN's transmission request.