How to Measure Force using FSR406 Force Sensor and Arduino

How to Measure Force using FSR406 Force Sensor and Arduino

3286 Views October 10, 2025 Afzal Rehmani
Arduino Uno R3 Projects & Tutorials

If you’ve ever wanted to detect pressure or measure how hard something is pressed using Arduino, this project is perfect for you. In this tutorial, we’ll show you how to measure force or pressure using an FSR406 Force Sensing Resistor (FSR) with an Arduino UNO and display the measured force in real time on a 0.96” OLED SSD1306 display.

What is an FSR406 Force Sensing Resistor?

An FSR (Force Sensing Resistor) changes its resistance depending on the pressure applied to its surface.

  • Higher pressure → lower resistance
  • Lower pressure → higher resistance

This change in resistance can easily be read using Arduino’s analog input pins. By processing this analog signal, we can calculate and display the corresponding force or pressure value on an OLED screen.

Project Overview

This simple Arduino project will help you:

  • Understand how analog sensors work
  • Learn about variable resistance and voltage dividers
  • Build your own pressure-sensing or weight-detection system

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Components Required

ComponentQuantityDescription
Arduino UNO1Main microcontroller board
FSR406 Force Sensing Resistor1Detects pressure/force
OLED Display (SSD1306, 0.96”, I²C)1128×64 pixel display module
10kΩ Resistor1Used in voltage divider circuit
Breadboard1For prototyping connections
Jumper Wires—For circuit connections

Circuit Diagram and Connections

FSR406 → Arduino UNO

FSR PinArduino Pin
One side of FSR5V
Other side of FSRA0 (connected via 10kΩ resistor to GND)

This setup forms a voltage divider circuit, where the analog pin (A0) measures the voltage that varies with the applied force.

OLED (SSD1306 I²C) → Arduino UNO

OLED PinArduino Pin
VCC5V
GNDGND
SCLA5
SDAA4

How It Works

  1. The FSR acts as a variable resistor whose resistance decreases when pressure is applied.
  2. Arduino reads the resulting voltage change on its analog input pin (A0).
  3. The analog value (0–1023) is converted into a force estimate (e.g., in Newtons).
  4. The force value is displayed on the OLED display and printed to the Serial Monitor.

When no pressure is applied, the resistance can be greater than 1MΩ. Under force, it drops drastically, resulting in a higher voltage reading.

Arduino Code

Below is the complete Arduino sketch to read FSR data and display the force on the OLED screen:

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define FSR_PIN A0  // FSR connected to analog pin A0

float smoothForce = 0;
float smoothingFactor = 0.15;

void setup() {
  Serial.begin(9600);
  
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  
  display.setCursor(10, 25);
  display.println("FSR406 Force Sensor");
  display.display();
  delay(2000);
}

void loop() {
  int fsrReading = analogRead(FSR_PIN); // 0–1023
  Serial.print("Raw: "); Serial.println(fsrReading);

  float mappedForce = pow((float)fsrReading / 1023.0, 2.5) * 100.0;
  smoothForce = (smoothingFactor * mappedForce) + ((1 - smoothingFactor) * smoothForce);

  display.clearDisplay();
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("FSR406 Pressure Test");

  display.setTextSize(2);
  display.setCursor(10, 25);
  display.print(smoothForce, 1);
  display.println(" N");

  display.setTextSize(1);
  display.setCursor(0, 55);
  display.println("Press sensor surface...");
  
  display.display();
  delay(100);
}

Output and Results

When you press the FSR406 sensor:

  • The OLED display shows the real-time force value increasing.
  • The Serial Monitor displays the corresponding analog readings.
  • Once released, both readings gradually return to zero.

Experiment Ideas

  • Measure grip strength or button press force
  • Integrate into a robotic gripper to detect object weight
  • Combine multiple FSRs to create a pressure-sensing mat or glove

Calibration Tips

FSR sensors are non-linear — readings depend on factors like resistor value, surface contact, and temperature.
For accurate force measurement:

  1. Use known weights (e.g., 100g, 200g, 500g) to record analog values.
  2. Plot a calibration curve in Excel or Python.
  3. Apply a custom mapping in your Arduino code for more precise results.

Conclusion

This project demonstrates how simple and powerful it is to measure and visualize physical force using an FSR406 Force Sensing Resistor, Arduino UNO, and OLED display.
With a bit of calibration, you can integrate this system into robotics, wearables, or pressure-sensitive devices.

Stay tuned to Circuits-DIY.com for more hands-on tutorials on Arduino, sensors, and IoT projects!

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