DMA and ADC connection

[mathias_edman]

Hi,

I am working with MPC5777C. At the moment I try to understand EQADC together with DMA. I have looked at many examples (for other MCUs since none exist for mine) and read quite a bit in reference manual.

As I understand it, for EQADC you can configure it so that it will be filled and drained by DMA automatically. This is done with IDCRx register:

"Generate DMA request to move data from the system memory to CFIFOx."

"Generate DMA request to move data from RFIFOx to the system memory."

For DMA you can easily configure the source and destination so that it will fill the EQADC command FIFO and drain the EQADC result FIFO.

But I struggle to understand what the connection is between the two. I mean how do EQADC know what DMA to trigger in order to fill or drain the FIFOs?

Regards,

Mathias

[davidtosenovjan · Accepted solution]

Hi, it is fixed according eDMA channel. DMA triggering must be initiated by eQADC module (by CFFFx and RFDFx flag) and its triggers particular DMA channel according the table below.

[mathias_edman]

Thanks for answering, very helpful!