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Issue with multichannel DMA operation for MCBSP on TMS320C6424

arun krishnan
Prodigy 80 points

Hi,

We are trying to configure MCBSP for 8 channel operation with DMA(CH0..CH7).

We are using Code Composer Studio 4.0 with BIOS 6.0. When we use Multichannel DMA, instead of witing to the next channel, the DMA is reading the sample from the 4th channel . So we get the output configuration some what like below.

DMA configured to receive data from MCBSP in the order 0,1,2,3,4,5,6,7.

Data read by DMA in this order : 0,4,1,5,2,6,3,7

We are allocating the memory for DMA from L2RAM(10800000).

Please suggest a solution to this problem.

 Regards,

Arun Krishnan

 

  • 0
    TI__Guru* 84110 points

    Some suggestions to help you find the reason for this incorrect behavior:

    To confirm that the McBSP and the data source are working correctly, do all the data handling with the DSP and not the DMA. You can poll the RRDY bit to see when data is ready, then read it into a single array for all the data, say 100 elements. After reading in all 100 elements, look at them and see if they would have been the correct data in the correct order 0,1,2,3,4,5,6,7.

    Once you have proven to yourself that the data coming to the McBSP is correct when read by the DSP, then try going back to using the DMA to respond to the RRDY events.

    It is not clear what you mean by "multi-channel DMA" for this application. All RRDY events will trigger the same DMA channel. You may use indexing to move from one channel's buffer to the next, but I am not sure what you want to happen with the data.