Force Sensor: Pressure to LED Brightness

Why it’s here

Relate a pressure input to output brightness.

How it works

The pressure control stands in for an ADC reading from a force-sensing resistor divider. It sets LED PWM through integer division by four. No force unit is inferred without calibration.

Try it

1. Open this experiment
2. Run and increase the input from 0 through 512 to 1023. Compare the monitor’s PWM value with the LED brightness.

Connections

• A0 — FSR voltage divider
• D9 ~ — LED through resistor

Example sketch

void setup() {
  pinMode(9, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  int pressure = analogRead(A0);
  analogWrite(9, pressure / 4);
  Serial.println(pressure);
}

Check your understanding

Does an input of 512 mean a force of 512 newtons?