ADSP-21065L Memory DMA

I am supporting a legacy product that is using the 21065L.  I would like to replace a memcpy() with a DMA copy to improve the throughput.

The original code is:

UNSIGNED32 *extMem = 0x10000000;

UNSIGNED32 *intMem = 0x0000D000;

memcpy(extMem, intMem, 100);

The DMA code is:

    // DMA off
    *pDMAC1 = 0;


    // set DMA control regs
    *pIIEP1 = (UNSIGNED32)(intMem); // internal RAM     
    *pIMEP1 = 1; // single increment
    *pCEP1 = 100; // count
    *pEIEP1 = (UNSIGNED32)(extMem); // external RAM
    *pEMEP1 = 1; // single increment
    *pECEP1 = 100; // count


    // turn DMA on
    *pDMAC1 = (DEN | TRAN | MASTER);


    // wait for DMA to finish, to keep the same flow as with memcpy
    while ((*pDMASTAT & DMA7ST) != 0);  

When I run this, nothing happens.  It doesn't hang, it just falls through with no memory writes at all.

I'm sure it's something simple, as I'm not familiar with this device.

TIA.

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  • After further experimenting, I determined that the reason the DMA didn't start was a bad destination address, as you suggested.  It now works correctly.

    However, I do observe that bit 7 is the correct one to monitor in DMASTAT for polling, as stated in the manual.  Bit 9 does not work for me.

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  • After further experimenting, I determined that the reason the DMA didn't start was a bad destination address, as you suggested.  It now works correctly.

    However, I do observe that bit 7 is the correct one to monitor in DMASTAT for polling, as stated in the manual.  Bit 9 does not work for me.

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