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TM4C1290NCPDT: SSI Advanced Mode with SSI Interrupt

Bryan Radke
Expert 1313 points
Part Number: TM4C1290NCPDT

Is there a reason why the SSI RXFF interrupt would not get handled when using SSI_ADV_MODE_READ_WRITE? I have both the TXFF and RXFF interrupts enabled when trying to get data from my slave. The TXFF gets called, which allows me to clock out the next byte. However, I never get the RXFF interrupt called.

  • 0
    TI__Guru**** 191026 points

    Hi Bryan,

      There is no RXFF interrupt per se if you meant an interrupt when the RX is completely full (e.g. 100% full). Rather, a RX FIFO interrupt can be generated when its FIFO is half-full or more. Since you are in full-duplex operation and each time you transmit, you may have also read the received data from the RXFIFO and therefore, you never crossed the half-full threshold. For experiment purpose, just change your code to Legacy mode. Do you still not see the RXFIFO interrupt? Another experiment, try not to read the RX FIFO data each time you transmit. Let's say you write to TX FIFO more than half-full (e.g. 5 or 6) bytes of data first before reading RX FIFO. Will you see the RX FIFO flag set?

      

  • 0 in reply to Charles Tsai
    Expert 1313 points

    Hello Charles,

    I was using the RXRIS bit for the RX FIFO half full, and it was not getting activated. I came back today, and now it's working as expected even though my code had not changed. I will continue to watch this issue.

    Bryan

  • 0 in reply to Bryan Radke
    TI__Guru**** 191026 points

    Hi Bryan,

      Glad your problem is resolved. You must have done some magic. :-) I will close the thread. In case you have new questions, please open a new thread.