LM35 Temperature Sensor Arduino — Wiring, Code & Proteus

The LM35 Temperature Sensor Arduino combo is the classic first analog project: three pins, one wire to A0, and you're reading temperature in °C. This tutorial covers the LM35 pinout, the correct ADC-to-°C formula, wiring for Arduino Uno, and a working Proteus simulation you can open before you touch hardware.

Welcome to this beginner-friendly Arduino tutorial on the lm35 temperature. By the end of the guide, you'll wire the module to an Arduino UNO, flash a short sketch, and read live values on the Serial Monitor — no prior electronics experience required.

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What you'll learn

• How the module works in plain language
• The exact parts you need and how to wire them safely
• The full Arduino IDE sketch with comments
• Common issues and how to fix them

Arduino code

Open the Arduino IDE, paste the sketch below into a new file, install any libraries the sketch #includes (Tools → Manage Libraries), select your board and COM port, then click Upload.

// LM35 is connected to this PIN
#define sensorPin A0

void setup() {
  // Init serial at 9600 baud 
  Serial.begin(9600);
}

void loop() {
  //Read Raw ADC Data
  int adcData = analogRead(sensorPin);

  // Convert that ADC Data into voltage
  float voltage = adcData * (5.0 / 1024.0);

  // Convert the voltage into temperature 
  float temperature = voltage * 100;

  // Print the temperature data
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println("*C");


  delay(800); // wait a second between readings
}

How it works

The sketch initialises serial communication and the lm35 temperature driver in setup(), then in loop() it samples the sensor at a regular interval and prints the result to the Serial Monitor at 9600 baud. Open the Serial Monitor (Ctrl+Shift+M) after upload to see live readings.

Troubleshooting checklist

• No readings: verify the baud rate in Serial Monitor matches the sketch (usually 9600).
• Garbage characters: wrong baud rate or loose GND wire.
• Library not found: install the exact library referenced in the #include line via Library Manager.
• Sensor not detected (I²C): run an I²C scanner sketch to confirm the address.

What to build next

Once the basic readout works, try logging values to an SD card, sending them over Wi-Fi with an ESP32, or pushing them to a Blynk IoT dashboard. Pair this module with our simulator round-up to prototype the circuit before soldering.

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