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ADS1015: ADC1015 - Is a delay between Set MUX via configuration and Read data necessary?

Robert Salasidis
Prodigy 10 points
Part Number: ADS1015

Tool/software:

I am trying to use an ADS1015 in a Meadow environment.

I need to switch the MUX input and scroll through a number of channels on 3 devices. I am using single shot reading. I find that unless I add a 1-2 mS delay between the channel configuration I2C command, and the Read I2C command, the analog data is unreliable (sometimes OK, sometimes not).

Adding the delay seems to fix this.

I looked in the datasheet, and did not find a specification for a delay requirement between the channel setting, and the conversion start. Does such a parameter exist, and if so, what is the right amount of time delay.

Thanks

  • 0
    TI__Mastermind 41751 points

    Hi Robert Salasidis,

    Our support person for this device is out of the office today, we will respond to you in the next 1-2 days

    Thanks for your patience

    -Bryan

  • 0
    TI__Expert 6080 points

    Hi Robert,

    What is the data rate being set in the configuration register? 

    There is no delay requirement between changing the mux channel setting, and the conversion start. There is only some delay in between the conversion start, and the conversion result being ready, which is dependent on the data rate setting. 

    After a conversion start command (write 1 to bit 15 in the configuration register), it will take some time for an ADC conversion to be ready. 

    The conversion will take about 1/DR (data rate) to be ready. If using the default data rate of 1600SPS for example, it would take about 1/1600 = 0.625ms for the conversion result to be ready. You should add ~10% to this delay before reading the conversion result, to account for Data Rate Variation:

    1ms is a reasonable delay in this case, if there isn't a need to sample faster.

    The best approach would be to simply use the ALERT/RDY pin functionality to monitor for when conversion data is ready.

    Best Regards,

    Angel