Arduino Resistance Measurement


The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor. It is measured in Ohms.

What you will learn?

  1. How to use arduino to measure resistance?
  2. How to apply simple ohms law?
  3. What are the different methods of resistance measurement?

Measurement of resistance (50 Ohm to 500K)

Measurement of resistance is again from V=I x R,  R = I / V or using voltage divider circuit.

  I = Vout / 1K
VRx = 5 – Vout
Rx = Vrx / I
Rx = (5 – Vout) / I
Rx = Resistance to be measured
VRx = Voltage Across Rx
I = Current flowing through voltage divider
Vout = Voltage measured by ADC

Resistance Measurement Circuit

Arduino Resistance Measurement Circuit
Arduino Resistance Measurement Circuit

Resistance Measurement Arduino Code

  Resistance Measurement -
  Reads an analog input on pin 0, converts it to resistance, and prints the result to the serial monitor.

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:

// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  // Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):
  float voltage = sensorValue * (5.0 / 1024.0);

  float I = voltage / 1000;
  float VRx = 5 - voltage;
  float Rx = VRx / I;
  Rx = (5 - voltage) / I;

  // print out the value you read:
  Serial.println(" Ohms");

Result of Resistance Measurement

Open the serial terminal and see the resistance value, in this experiment I found that if you remove zero from 5.0 and make it 5 or 1024.0 to 1024 the code will not work.

Result Resistance Measurement
Result Resistance Measurement

This circuit is suitable for higher values of resistance only to measure lower value resistance Low Value Resistance Measurement circuit is use.

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