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SDA(NSS) pin of RFID RC522 isnt working


I'm working on a mifare card key program using TI-RTOS but my SDA(NSS) signal has an error.

It has an up board that coundt be there.
I tried having a close look into the SPI.h code but i cant find the line about the SDA (NSS) signal.
Please help me.

  • Not sure what your SDA is? (Generally, that's a I2C pin, not SPI)

    The chip select scrobe in your ENABLE signal is probably generated by the SPI (SSI) controller if you are on a Tiva device (which device are you on?). The TI-RTOS SPI driver does not have a concept of an integrated chip select. If the hardware chip select doesn't work for you, you can do a few things.

    1. You can perhaps change the Phase and Polarity of the SPI controller in a mode that doesn't strobe the _CS pin. See the device's datasheet / User manual, it probably has the waveforms documented there.

    2. You can use a software GPIO pin rather a hardware chip select. In this case, you need to assert and deassert the pin yourself before and after calling SPI_transfer.

    3. (Unlikely solution) You can use a SPI frame size of 16 (if its supported, docs in the datasheet) and then you wouldn't see the strobe between the 2 bytes (and your data would be packed in a 16-bit word)