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Original question:

LMP91000EVM: issue with using 91000EVM software on Windows 10

LMP91000EVM: problem with conducting Cyclic voltammetry experiments; no change in output

Yomna ElSaboni
Prodigy 80 points
Part Number: LMP91000EVM
Other Parts Discussed in Thread: LMP91000

Hi Gordon, 


I spoke to you early this year about this board and I was trying to use it to CV measurements using SPIO4 board and you suggested my board could be damaged and that is why it isnt working. You were right we got a new one recently and I am trying to use it and the software is working fine thankfully and it is recognizing all the boards, but I am not sure how to conduct the cyclic voltammetry experiments, because every measurement I make is more or less is the same regardless if the electrodes are connected or what the solution is, how can I know the settings of the software to make my experiment. 

Also, every time I pick a sensor from the list in the software, I get a message saying I need to open 2-wire jumper although I did remove the jumper on the board. Is there something inside the program that I need to change?

Thank you. 

Yomna 

  • 0
    TI__Genius 9310 points

    Yomna,

      I am happy that you are up and running. 

    Most likely you do not have the EVM configured correctly for your probe. The sensor manufactures have basic settings for their sensors. However these basic settings don't always apply to every design or IC that can be used to measure the sensor. The LMP91000 is a transimpedance amplifier that is very sensitive and low current. Small adjustment to gain and Rload will have big impact to your readings.

    Most designers, begin with the incorrect settings for the LMP91000 board. 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 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.