While reading voltage readVoltage(a, 'A0'), i am always getting 5 volts, irrespective of if the sensor is in air, or water or soil. What may be the reason?

a = ardunio('COM3', 'uno');

moisture_reading = readVoltage(a, 'A0');

disp("moisture reading is " moisture_reading);

Always getting 5 reading, irerespective of the place where the moisture sensor is, i.e. in air or in water or in soil.

[DGM]

You're asking people to debug an ad hoc circuit and some code without seeing any of it. Establish something that is known. Put a known voltage on a pin and verify that it can be read. Read the sensor output with a known meter and verify that it responds.

Answer 1

[Shuba Nandini]

Hi Shivam,

It is my understanding that, readVoltage(a, 'A0') is always giving a reading of 5 volts irrespective of if the sensor is in air, or water or soil. There could be multiple reasons why readVoltage(a, 'A0') is always giving a reading of 5 volts.

• By default, the Arduino's reference voltage is set to 5 volts. If the sensor is operating at a lower voltage level, this could cause the issue. You can try setting the reference voltage to match the sensor's operating voltage.

To set the reference voltage, you can use the analogReference() function. For example, if you are using a 3.3V voltage supply, you can use the following command:

analogReference(a,EXTERNAL);

• It is also possible that the sensor is not functioning correctly.
• Please make sure that the sensor is connected to the correct pin on the Arduino board.
• Ensure the Arduino board has a proper grounding connection. If there is poor grounding, there could be error in the readings, which may result in incorrect values.
• Check the code for errors or bugs. Please make sure that the “readVoltage” function is used correctly.

To know more about “AnalogReference” function, please refer to:

Connection to the Arduino and Arduino-compatible ESP32 hardware - MATLAB

Hope this helps!