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AM2634: MCSPI DMA – Receiving Same Data on RX Without External Connection.

Sahil M
Prodigy 65 points
Part Number: AM2634

Tool/software:

Hi Team,

I'm currently working with the mcspi_loopback_dma example code and have configured it for SPI4. However, I’m facing an issue where, without any external loopback connection, the RX buffer is receiving the same data that I transmit.

I'm unsure if I’ve missed any configuration. I'm sharing my code below for reference. Kindly guide me if there is anything wrong or missing in my setup that could cause this behavior.

mcspi_loopback_dma_am263x-cc_r5fss0-0_nortos_ti-arm-clang.zip

Best Regards,

Sahil M.

  • 0
    TI__Guru**** 196526 points

    Hi Sahil,

    It is expected. The loopback is enabled in your configuration.

    The loopback can be utilized to test the SPI transmit and receive paths, including the shift registers, the buffer registers. In this mode the transmit signal is internally feedback to the receiver, whereas the SPI_Dx and SPI_CLK pin are disconnected; that is, the transmitted data is internally transferred to the corresponding receive buffer while external signals remain unchanged.

    This mode allows the CPU to write into the transmit buffer, and check that the receive buffer contains the correct transmit data.