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Original question:

TINA/Spice/ADS1115: Data converters forum

ADS1115: using ALERT/RDY pin iwhen OS done

Hemi Shay Mizrahi
Prodigy 70 points
Part Number: ADS1115

Hi,

I am using the ADS1115 to measure 4 different analog channels. The range of 3 of the 4 channels is 0 – 1.024V, the range of last one is 0 – 2.048V.

Now I am checking only one channel (up to 1.024V), but later I will check all of them.

I would like to use the ALERT/RDY pin for detecting whenever the conversion is over, but I could not get it works with the datasheet instructions (or maybe I did not understand them).

Please help.

 

Thanks,

 

Hemi

  • 0
    TI__Guru* 94295 points

    Hemi,


    The ADS1115 uses a digital comparator to trigger the ALERT/RDY pin. The pin is triggered every time the ADC output (whatever data is in the conversion register) is higher than the Hi_thresh register or lower than the Lo_thresh register.

    If you set the Lo_thresh register higher than the Hi_thresh register then the comparator should trigger each time. To do this, you can set the Lo_thresh register to 7FFFh (which would be positive full scale) and set the Hi_thresh register to 8000h (negative full scale). This means that regardless of whatever the ADC puts out, the ADC will trigger one of these two thresholds.

    You just need to set the COMP_MODE to a traditional comparator, COMP_LAT to a non-latching comparator, and set COMP_QUE to assert after one (each) conversion.

    One thing to note about changing channels and configurations. When you write to the configuration register, the new configuration does not get set until AFTER the ADC conversion in progress completes. When this happens, you could write the new configuration, but the next ALERT/RDY would give you the previous configuration ADC data. Because of this, I find it's easier to keep track of conversions when using single shot conversion mode.


    Joseph Wu

  • 0 in reply to Joseph Wu
    Prodigy 70 points

    Thanks Joseph for your support.

    It works :-)

    Hemi