Turn a knob and watch the numbers change.

A potentiometer gives you a controllable analogue voltage. You will wire it as a three-terminal voltage divider, read the wiper on A0, and display both the raw 0–1023 value and a useful percentage in the Serial Monitor.

What you need

Arduino UNO
10 kΩ linear potentiometer
Breadboard and jumper wires

Goal: create a smooth manual input that spans almost the full analogue input range.

▶ YOUTUBE DEMO PLACEHOLDERSuggested: “Arduino Potentiometer — Read 0 to 1023 on Serial Monitor”

Wire the potentiometer correctly

One outer pin → 5 V
Centre pin / wiper → A0
Other outer pin → GND

Although people often call this a variable resistor, here the potentiometer is being used as a voltage divider. The centre wiper slides between 0 V and about 5 V as you turn the shaft.

If the knob works backwards: swap the two outer connections. Leave the centre wiper on A0.

Print raw value and percentage

const int potPin = A0;

void setup() {
  Serial.begin(9600);
}

void loop() {
  int rawValue = analogRead(potPin);
  int percent = map(rawValue, 0, 1023, 0, 100);

  Serial.print("Raw: " );
  Serial.print(rawValue);
  Serial.print("   Percentage: " );
  Serial.print(percent);
  Serial.println("%");

  delay(100);
}

The UNO uses a 10-bit analogue-to-digital conversion for analogRead(), giving 1024 possible codes from 0 to 1023.

Experiments

Turn the knob fully both ways and note the actual minimum and maximum values.
Stop at approximately 25%, 50% and 75%.
Change map() so the displayed range is 0–255 instead of 0–100.
Use the mapped value to change a delay time between 50 ms and 1000 ms.

Challenge

Use the knob to control how fast the built-in LED flashes. At one end it should blink slowly; at the other end it should blink quickly.