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RTOS/TM4C1294NCPDT: DMA SPI TX in pingpong mode

Manohar B
Intellectual 610 points
Part Number: TM4C1294NCPDT


Tool/software: TI-RTOS

Hi,

I am using SPI TX through DMA in pingpong mode as SPI is configured as slave device.

I have configured the SPI to DMA interrupt DMA transfer complete interrupt, This interrupt will raise request if the transfer is completed.

Since I have configured the device in slave mode, it will wait for clock from master then only data will be send out of the device.

But without master clock, the interrupt is getting triggered and the ping pong is performing transfer alternately even in slave mode.

Regards,

Manohar

  • 0
    TI__Guru*** 135355 points
    Hello Manohar,

    While your setup is presented quite well, I am not clear what your question is. Can you please clarify your concerns/questions?
  • 0 in reply to Ralph Jacobi
    Intellectual 610 points
    Hi,

    My question:

    1. I have configured my SPI DMA as Slave in ping pong mode. Without the clock from master, The DMA continuous the transfer from DMA buffer to SPI buffer and not out of SPI buffer.
    I think its overwriting the SPI buffer, When I initiate a transfer from another device as master. The received data in master device is not uniform. It keep on varies.
    (E.x)Buffer data in Slave device is 1,2,3,4 . But I am receiving as 2,3,4,1.
    Don't know why this mismatch is happening.