Question : If I have the highest priority channel servicing the serial port at a rate of 500 nS/ transfer, is it possible for the next highest priority channel to service the EMIF port between the serial port transfers?

Answer : The lower priority channel will be allowed to service the EMIF between serial port transfers.

The way the DMA works, the highest priority channel which is not waiting on a synchronization event (or paused, or stopped) gets to execute its transfers.

Note that if a high priority channel has control, then a low priority channel must wait until it is either paused, stopped, or waiting for a sync event in order to go.

Because of this, the higher priority channels should be used to service sync'd events, as they will disrupt a block transfer. Once the event is serviced, control will return to the other channel.

Since there are four channels, 0 and 1 should be used to service the serial ports, with 2 and 3 being used for block moves.