This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMP91200: Not getting proper values on ADC

Part Number: LMP91200

Hi sir,

I have query regarding interfacing of lmp91200 ic
not getting proper values on adc.
I was tried to read analog signal using arduino nano board
I have configured adc read in loop() at every 500 ms
when i have change ph buffer no value is changing.

I am just checking adc raw values with different ph buffer solution
I have attached working ph sensor with ic
I am operting that ic on 3.3V DC Voltage
I have also given VREF = 3.3V
and i have attached vout to microcontroller adc
so when i am changing ph buffer solution not getting proper analog output.
means i have 10 bit adc resolution on microcontroller
but adc raw value getting from lmp91200 continues varying.


  • Frank,

    Most designers, begin with the incorrect settings for the LMP91200 board. The software needs to be configured for your probe. In the GUI Software find a sensor that is similar or the same as you are using and change to these default values to begin. Only if you are using a standard solution with the sensor can you know exactly what value you should be getting. Adjust the settings until you get the correct voltage feedback for the standard you are using. 

    Try adjusting the gain and Rload after you configure the GUI for your probe. This should get you a good reading. You will have to craft a formula to get the real values from the voltages you will be measuring. Use the standards to get known voltage for know standards then you will be able to create the formula. Don't forget to temperature compensate the voltage to get more accurate measurements.