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  • TI Thinks Resolved

OMAP-L137: Using McAsp FIFOs on C6747

Part Number: OMAP-L137

Hi,

I am targeting the OMAP-L137 evaluation board.  I've created a bare-metal (no OS or TI libraries) McASP loopback test.  I have enabled the FIFOs, and setup the registers to read and write 8 slots at time on one transmitter and one receiver.  

I first tried to setup a 16-slot frame, where the first 8 slots were transmitter slots; and the remaining 8 slots were receiver slots.  This didn't work.  The data I read back from the FIFO was always 0.  Where each word that was transmitted was one greater than the previous.  

When I changed it to an 8-slot frame, with the transmitter and receiver both enabled on all 8 slots, it worked as planned.  

So my question is a matter of understanding how to setup frames and slots.  It's my understanding that, in addition to the steps to setup the working case, if I change:

RTDM: 0xFF

XTDM: 0xFF

AFSRCTL.RMOD: 8

AFSXCTL.XMOD: 8

TO: 

RTDM: 0x00FF

XTDM: 0xFF00

AFSRCTL.RMOD: 16

AFSXCTL.XMOD: 16

I would have setup a 16 slot frame where the where the transmitter is only active during the first 8 frames, and the receiver is only active during the remaining 8 frames.  

What am I failing to understand?

Thanks!

  • Hello,

    Please use this forum e2e.ti.com/.../42 for OMAP-L137.
    I am closing this thread.

    BR
    Margarita

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