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CC3220SF-LAUNCHXL: How to enable SPI DMA?

Markel Robregado
Guru 86745 points
Part Number: CC3220SF-LAUNCHXL
Other Parts Discussed in Thread: CC3220SF

Hi,

    I read at UART Echo TI-RTOS Example Program that to enable DMA, just set TI_DRIVERS_UART_DMA at predefined symbols. How do I set DMA for SPI? Also, which code file has this TI_DRIVERS_UART_DMA?

    I am trying to implement SPI DMA driver for NeoPixel Ring RGB leds.

-kel

  • 0
    TI__Mastermind 38980 points
    Hi Kel,

    DMA should be enabled on SPI when you cross the minDmaTransferSize threshold attribute defined in CC3220SF_LAUNCHXL.c. Please be sure that you are using CC3220 SDK 1.60, as there is a known SPI + DMA issue in v1.50.

    All CC3220-specific TI Drivers implementation are available in the peripheral folders in source/ti/drivers.

    Best regards,
    Sarah
  • 0 in reply to Sarah P
    Guru 86745 points
    Hi Sarah,

    Thanks for your reply. I am still learning how to implement SPI DMA. How do I "cross the minDmaTransferSize threshold attribute"? If I increase the value by +1 would that SPI DMA will be enabled?

    -kel
  • 0 in reply to Markel Robregado
    TI__Mastermind 38980 points
    Hi Kel,

    Yes, if you complete a SPI transfer larger than the threshold minimum, the device will automatically use DMA. You can change the threshold minimum as well.

    Best regards,
    Sarah
  • 0 in reply to Sarah P
    Intellectual 731 points

    Hi Sarah,

    I am using AWS IoT Plugin and it only *officially* works with SDK 1.4 although I am using it with 1.5 with no problems so far.

    What is the SPI DMA bug you speak of? Is there a work around I can use without updating the SDK to 1.6?  Unfortunately, the AWS IoT examples won't compile with 1.6.

  • 0 in reply to ironman
    Intellectual 731 points
    Update:

    The problem I was having with SPI DMA transfers was that when I set minDmaTransferSize = 1 (in order to force use of the DMA), only the first frame would be transferred. It seems like the DMA interrupt wasn't telling the SPI hardware to send the next frame.

    When I set minDmaTransferSize to something larger than the message I'm trying to send, the SPI driver went into polling mode and everything worked correctly.

    I looked into the differences between the SPI and DMA drivers in Simplelink SDK version 1.50.00.06 and 1.60.00.04.

    UDMACC32XX.c - No Change
    UDMACC32XX.h - No Change
    SPICC32XXDMA.c - Different
    SPICC32XXDMA.h - No Change

    Added the new SPICC32XXDMA.c to my project and SPI DMA works now.
  • 0 in reply to ironman
    TI__Mastermind 38980 points
    Hi ironman,

    Copying SPICC32XXDMA.c and .h from v1.60 into your project will resolve the issue. There was a bug introduced in v1.50 that stopped the SPI DMA transfer prematurely, and the fix was included in v1.60.

    Best regards,
    Sarah