I'm trying to measure the voltage using a voltage sensor. If the power source is activated, the sensor outputs 2.6V, and if deactivated it outputs around 20mV.

However, If I connect the signal pin to the ADC pin on the Raspberry Pi Pico, the output voltage of the sensor drops to ~50mV. Thus, I can't measure anything because the ADC pin always outputs the same value.

This voltage drop does not happen if I connect the signal pin on the sensor to any other GPIO pin on the Pico.

Is this normal behaviour or are my ADC pins broken?

  • Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Community Bot
    Aug 27, 2023 at 19:41
  • The ADC cant OUTPUT something, its a INPUT! And add a schematic drawing, it is highly likely you have either a short circuit or have connected the wrong GPIO to your sensor.
    – MatsK
    Aug 31, 2023 at 6:15
  • To add to @MatsK comment it's also possible you have a software issue and the ADC pin has been accidentally configured as an output set to 0 (low) rather than an ADC input. Jan 3 at 17:50


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