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MSP432P401R: ADC14 error for measured voltage in msp432

Part Number: MSP432P401R

Hi,

I am using a MSP432P401R Red Launchpad. I am trying to interface an LM35 temperature sensor with the controller and display the same over a K350 QVGA display. The LM35 is interfaced at P5.5 with ADC MEM15. 

The issue I am facing is that the microcontroller is unable to show the proper room temperature. The program I have writtten is working as desired sinceif the adc is fed with onboard 3.3 V supply, it shows 3300mV as output on the display. But on interfacing the same with LM35 gives weird output which is much higher or lower with respect to room temperature. Inorder to verify if the LM35 is working fine, I measured the output signal with DMM and it was showing 310 mV which is same to room temperature. But on interfacing it with msp432, the DMM reading keeps fluctuating around 160 mV and higher. Also an important thing i noticed is that when i measured the voltage at ADC channel i.e. P5.5, DMM gives reading of around 80mV and I guess its much greater that it should be.

Regards,

Amit Kotal 

  • Are you doing anything else with port 5 bit 5?
  • In reply to Keith Barkley:

    Hi Keith,
    Thanks for your reply. No I am not using PORT 5 bit 5 for any other purpose.

    Regards,
    Amit Kotal
  • In reply to Amit Kotal:

    The LM35 has a very low impedance, so it should be fine. Two WAG's:
    Try a pot on 5.5
    Use a different ADC input, you might have ESD'd it.
  • In reply to Keith Barkley:

    Amit,
    Just curious if you were able to try any of Keith's suggestions and if you could discern if the port was damaged.

    Thanks,
    Chris
  • In reply to Chris Sterzik:

    Hi Chris,

    Indeed the issue was with the port pins of the LaunchPad.

    Regards,

    Amit Kotal

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