Trimmer Potentiometer with ESP8266 (Step-by-Step Guide)

Introduction

A potentiometer is a variable resistor that allows you to adjust resistance manually. A trimmer potentiometer (or trimpot) is a small, adjustable version usually used on PCBs for fine-tuning voltage, brightness, contrast, or calibration in circuits.

When we connect a trimmer potentiometer with the ESP8266, we can use it as an analog input device. For example, we can read the resistance value and use it to:

• Control the brightness of an LED
• Adjust motor speed
• Set thresholds in sensor projects
• Tune IoT devices dynamically

Since the ESP8266 has only one ADC pin (A0), we will connect the potentiometer to it and read values ranging from 0 to 1023.

Components Required

• ESP8266 (NodeMCU / Wemos D1 Mini)
• Trimmer Potentiometer (e.g., 10kΩ)
• Breadboard
• Jumper Wires
• USB Cable

Circuit Diagram (Potentiometer → ESP8266)

• Middle pin (wiper) → A0
• One side pin → 3.3V
• Other side pin → GND

⚠️ Note: ESP8266 ADC works on 0–3.3V only, so don’t supply 5V to the potentiometer.

Arduino Code for Trimmer Potentiometer with ESP8266

// Trimmer Potentiometer with ESP8266
int potPin = A0;   // Potentiometer connected to analog pin A0
int potValue = 0;  // Variable to store potentiometer value

void setup() {
  Serial.begin(115200); // Start Serial Monitor
}

void loop() {
  // Read potentiometer value (0 to 1023)
  potValue = analogRead(potPin);

  // Print value to Serial Monitor
  Serial.print("Potentiometer Value: ");
  Serial.println(potValue);

  delay(500); // Wait 0.5 seconds
}

Step-by-Step Code Explanation

Pin Declaration

int potPin = A0;

Setup Function

Serial.begin(115200);

Loop Function

potValue = analogRead(potPin);
Serial.println(potValue);

analogRead(A0) reads values between 0 and 1023 depending on the position of the potentiometer.

The value is printed on the Serial Monitor.

Output

• When the potentiometer knob is turned fully towards GND → Value ~0.
• When turned fully towards 3.3V → Value ~1023.
• Intermediate positions give values between 0 and 1023.

Real-Life Applications

1. Brightness Control
   • Use the potentiometer value to control LED brightness with PWM.
2. Volume Control
   • Potentiometers are used in amplifiers and radios as volume knobs.
3. Sensor Calibration
   • Set threshold levels for gas sensors, temperature cutoffs, etc.
4. Motor Speed Control
   • Adjust DC motor speed in automation projects.
5. IoT Applications
   • Use the potentiometer as a manual input device for IoT dashboards.

Troubleshooting

• Getting only 0 or 1023 values:
  • Check wiring of the 3.3V, GND, and wiper pin.
  • Make sure the potentiometer range is within ESP8266 ADC voltage (0–3.3V).
• Values fluctuate too much:
  • Use a stable breadboard connection.
  • Add a small capacitor (~0.1µF) across the potentiometer to reduce noise.
• ESP8266 not reading analog values properly:
  • Some ESP8266 boards (like NodeMCU) have an onboard voltage divider on A0, so ensure your potentiometer output does not exceed 3.3V.