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C6657 McBSP throughput in TDM mode

Nori Shinozaki
Intellectual 2430 points

Hello champs,

I need to achieve 36.864 Mbps in McBSP in TDM mode.

From the C6657 Data Manual(SPRS814A), the max bit clock is 50MHz, so I thought it should be Ok.

However I found this note in "7.22.2.1 McBSP Timing".

"the maximum usable speed may be lower due to EDMA limitations and AC timing requirements"

Then I found this comment,
"on 6455 I saw issues when going over 20 MHz because EDMA could not keep up due to transfer latency" in
http://e2e.ti.com/support/dsp/tms320c6000_high_performance_dsps/f/112/p/31657/110333.aspx#110333

As long as McBSP can only requets EDMA to transfer by 1 element, it is also true to C6657.

Is there other way to go over 36.864 Mbps or closer to 50 Mbps?

Regards,
Nori Shinozaki

  • 0
    TI__Genius 12065 points

    Nori,

    For C6657, the McBSP module seems to be able to achieve 50Mbps in loopback mode with internal clock (CPU/6=166MHz with 1GHz CPU clock) and CLKGDV=2.

    The testing is using EDMA with FIFO enabled and word length=32bit.

    But I am not sure about the data rate in TDM mode and with external clock.

    There is one McBSP example project in C5567 PDK package. The default mode is internal loopback mode. But you probably can start from there and extend the test case to get the feel of the McBSP throughput in real setup.

    Hope it helps.

  • 0 in reply to Steven Ji
    TI__Intellectual 2430 points

    Hello Steven,

    Thanks, good to know that!

    Regards,

    Nori Shinozaki