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DAC7760 (Eval-Board) interfacing with TMS320F28377D (EVAL-BOARD),trying to communicate with SPI.

Thanks for your fast response !

I am not able to attach the Saleae File capture, so sending out a screenshot.  

The SPI-CLK is running at 781 KHZ .  The following details are regarding the capture-

1> Channel 3 is the Latch signal giving from the DSP(by using a GPIO). 

2> I am not able to get latch exactly at  LSB of the data.

3> Also as I mentioned before, if I don't give the  delay between consecutive transmissions (say between consecutive WRITES) I observe that  just the last/recent transmission being transmitted. Might be because  I am writing to the register too fast , that it has not completed the previous transmission.

I request for your guidance on these issues.

Thank You,

-Prashanth 

  • Hi Prashanth,

    Thank you for the screen capture. It looks to me as though you are trying to latch data on the falling edge. This device latches data on the rising edge of SCLK.
  • I am not able to see the 24 bit transmission if I don't give the delay between consecutive transmissions (say between consecutive WRITES) I observe that just the last/recent transmission being transmitted. Might be because I am writing to the register too fast , that it has not completed the previous transmission.
    Is SCLK slow to take the data out from the MCU?

    Thank You Sir,
    Prashanth
  • Can you provide a capture of this case as well?

    The SCLK being slow should only improve the performance of the SPI. As long as the data is being latched on the correct SCLK edge.

  • Sure, I will provide the capture for that as well.
    Right now , I am trying to use TX-Interrupts with TX-FIFO to generate an interrupt as soon as I send 24 bits (i.e 3 x 8-bit transmissions) so that I can Latch(i.e I am making the GPIO HIGH to have rising edge of Latch synchronize with LSB of the transmission) the data at the LSB of the transmission. But the TX-Interrupts is going HIGH, as soon as I initialize the configuration registers .
    Please help me regarding this.

    Thank You,
    Prashanth
  • Hi Prashanth,

    Prashanth Prakash41 said:
    Right now , I am trying to use TX-Interrupts with TX-FIFO to generate an interrupt as soon as I send 24 bits (i.e 3 x 8-bit transmissions) so that I can Latch(i.e I am making the GPIO HIGH to have rising edge of Latch synchronize with LSB of the transmission) the data at the LSB of the transmission. But the TX-Interrupts is going HIGH, as soon as I initialize the configuration registers .
    Please help me regarding this.

    In this forum we only focus on the data converter support.

    To get better assistance with your request, you will need to post your questions in the MCU forum.