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PROCESSOR-SDK-C6748: Dev Kit problems with SPIO0 SOMI

Javier Villegas
Prodigy 25 points
Part Number: PROCESSOR-SDK-C6748


I am trying to connect a slave device to the SPI0 port using the C6748 Development Kit. I put 0 ohms resistors in SIMO, MOSI, Clk and Cs5 (R214,R215,R216  and R219)  and take away resistors R172, R178,R179 and R184.  Everything seems to be working fine in the SIMO, clck and CS pins. The slave device is returning the expected waveform in the SOMI line, but the 6748 SOMI is always reading zeros. I checked the PinMux registers and they are configured correctly, I tested changing the SOMI pin as a GPIO input and I have the same problem, it reads everything as a zero. Any suggestions?

  • 0
    TI__Guru**** 161600 points
    How is the SPI Pin Control Register 1 (SPIPC1) set? Especially bit 11 SOMIDIR:
    " SPIx_SOMI pin direction. Controls the direction of the SPIx_SOMI pin when it is used as a general purpose I/O pin. If the SPIx_SOMI pin is used as a SPI functional pin, the I/O direction is determined by whether the SPI is configured as master or slave.
    0 SPIx_SOMI pin is an input.
    1 SPIx_SOMI pin is an output "

    Best Regards,
    Yordan
  • 0 in reply to Yordan Kovachev
    Prodigy 25 points
    Hello Yordan,
    All bits in SPIPC1 are 0 (input), even the SPI outputs that are working fine. This is consistent with the documentation (same that you quote) that says that this value is only relevant if the pins are configured as GPIOs.