AD7671 interfacing with ADSP21369


I am currently working on interfacing AD7671 with ADSP21369 using SPI communication protocol. Here ADSP acts as master and ADC as a slave. I have configured all the spi registers, srus. I am struck how to use ADC's CNVST pin to read the converted values from ADC to ADSP. Could you please help me on this

  • +1
    •  Analog Employees 
    on Sep 18, 2019 3:11 PM over 1 year ago

    Hi savitha,

    Apologies for the late response.

    I'm not very familiar with the ADSP21369 myself, but there's a figure in the AD7671 data sheet that gives an example connection diagram with a typical SPI. See figure 22 on page 20 of the AD7671 data sheet.

    It shows the CNVST pin connected to a generic "I/O Port," which must be programmed to be synchronous to the SPI read instructions which read back the ADC results. If the ADSP21369 has the ability to generate an output from its timer peripheral, then that may be the best way to ensure a periodic CNVST signal reaches the AD7671. I've used one of our Blackfin DSP processors in the past to trigger an interrupt off a timer to change the state of GPIOs controlling other peripheral circuitry around our ADCs, but I haven't yet tried this with a convert-start signal as I'm suggesting here.

    Hope that helps. Let me know if you have further questions.


  • Hi Tyler,

    Thanks for the response.

    Could you pls tell me how to make this "synchronous to the SPI read instructions which read back the ADC results". Could you pls share the sample code if any. also pls share the Blackfin DSP code which you have done.

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