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ADS8685: Command to read conversion result

Jack Lucas
Prodigy 40 points
Part Number: ADS8685


Hello,

Something that is unclear to me in the ADS868x datasheet is how you actually read the conversion result. I understand how you would send a command to read/write data to the configuration registers, but what do you do to simply read the conversion result? Do you just send no command at all, holding SDI low?

Thank you.

  • 0
    TI__Mastermind 45995 points

    Hi Jack,

    To read conversion data, there is no command needed. There are four steps to start a conversion and read back the data from the ADC:

    1. Your host controller pulls CONVST/CS signal from low to high to initiate a data conversion.

    2. After detecting a rising edge of RVS signal or waiting for tconv_max time specificed in the datasheet instead of monitoring RVS signal, your host controller can pull CONVST/CS to low to start a data transfer frame

    3. During the frame, the host controller provides clocks on the SCLK pin to clock out the conversion data from the ADC. To provide clocks, your controller has to send some data to the SDI line, using NOP (0x0000) command is a good solution to send out the clocks from the host controller.

    4. Your controller pulls the CONVST/CS pin high to end the data transfer frame.

    I hope this helps.

    Thanks&regards,

    Dale