I set up a humidity meter with a microcontroller, but no matter how much I adjust, the display does not mark zero, even though the sensors are separated in the air. What could be happening?
When we have a high impedance sensor connected to the inputs of any circuit, if the cable is somewhat long, many noises can be picked up, especially those resulting from the power grid. Thus, even if there is a processing circuit that sends the signals in digital form, the pulses can be added to the information affecting its minimum. The cables connecting the sensor circuit to the microcontroller, if they are more than 10 cm long, must be shielded and the mesh properly grounded connected to the zero volt point or GND of the microcontroller board.
