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ADS125H02: AD conversion operation after power-on

toru morichi
Prodigy 40 points
Part Number: ADS125H02

Tool/software:

To reduce the number of connection pins between the ADS125H02 and the CPU, /RESET (pin 7) and START (pin 8) are pulled up to DVDD.
In this case, when a power-on reset is performed by turning on the power, will the registers be initialized and AD conversion automatically start in continuous conversion mode (20 sps)?
Also, when changing the settings, is it okay to send a stop command to stop AD conversion, then set the registers and finally send a start command?

  • 0
    TI__Mastermind 41461 points

    Hi toru morichi,

    Answers to your questions are below

    toru morichi said:
    In this case, when a power-on reset is performed by turning on the power, will the registers be initialized and AD conversion automatically start in continuous conversion mode (20 sps)?

    This is correct. With the START pin pulled high, the ADC will automatically start converting. You can verify this by probing the DRDY pin, which should pulse at approximately the default data rate (20SPS). If you want to control conversions using the commands, hold the START pin low as per the datasheet

    toru morichi said:
    Also, when changing the settings, is it okay to send a stop command to stop AD conversion, then set the registers and finally send a start command?

    Yes, this is okay. You can also see that writing to some registers will automatically restart the conversion. So if you write to these specific registers in continuous conversion mode, the ADC will automatically restart with you having to send the commands.

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 40 points

    Hi Bryan.

    Thank you for your reply.

    Let me confirm again.

    I understand that if the power is turned on with the START pin pulled up, the ADC starts in continuous conversion mode, and the DRDY pin changes at a cycle of 20 sps.
    I also understand that if a stop command is sent in this state, AD conversion stops and the DRDY pin stops changing.

    So, if I change even one register (for example, changing MUX and GAIN in the MODE4 register), will AD conversion automatically restart since the START pin is pulled up?
    Or, even if I change some registers, will AD conversion remain stopped until the START command is sent?

    Thank you in advance.

  • 0 in reply to toru morichi
    TI__Mastermind 41461 points

    HI toru morichi,

    toru morichi said:
    I understand that if the power is turned on with the START pin pulled up, the ADC starts in continuous conversion mode, and the DRDY pin changes at a cycle of 20 sps.

    Correct

    toru morichi said:
    I also understand that if a stop command is sent in this state, AD conversion stops and the DRDY pin stops changing.

    Correct

    toru morichi said:
    So, if I change even one register (for example, changing MUX and GAIN in the MODE4 register), will AD conversion automatically restart since the START pin is pulled up?

    Correct, assuming the ADC is converting. If you have stopped the ADC conversions (by issuing the STOP command or taking the START pin low), the ADC will not automatically restart conversions even if you change those specific registers.

    -Bryan