ESP32 - LM35 Temperature Sensors

Video Tutorial

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Hardware Required

Introduction to LM35 Temperature Sensor

LM35 Temperature Sensor Pinout

LM35 temperature sensor has three pins:

• GND pin:connect this pin to GND (0V)
• VCC pin: connect this pin to VCC (5V)
• OUT pin: This pin outputs voltage in proportion to the temperature value.

How LM35 Temperature Sensor Works

The LM35 sensor outputs the voltage in linearly proportion to the Celsius temperature. The output scale factor of the LM35 is 10 mV/°C. By measuring the voltage on the LM32's OUT pin, we can calculate the temperature value.

Wiring Diagram

Schematic Diagram

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Breadboard Connections

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click to see ESP32 pin out

ESP32 Code

#define ADC_VREF_mV    3300.0 // in millivolt
#define ADC_RESOLUTION 4096.0
#define PIN_LM35       36 // ESP32 pin GIOP36 (ADC0) connected to LM35

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

void loop() {
  // read the ADC value from the temperature sensor
  int adcVal = analogRead(PIN_LM35);
  // convert the ADC value to voltage in millivolt
  float milliVolt = adcVal * (ADC_VREF_mV / ADC_RESOLUTION);
  // convert the voltage to the temperature in °C
  float tempC = milliVolt / 10;
  // convert the °C to °F
  float tempF = tempC * 9 / 5 + 32;

  // print the temperature in the Serial Monitor:
  Serial.print("Temperature: ");
  Serial.print(tempC);   // print the temperature in °C
  Serial.print("°C");
  Serial.print("  ~  "); // separator between °C and °F
  Serial.print(tempF);   // print the temperature in °F
  Serial.println("°F");

  delay(500);
}          

Book Tutorial

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See Also

• ESP32 - Button - Debounce
• ESP32 - Button - Long Press Short Press
• ESP32 - Button Toggle LED

References

• Arduino IDE
• ESP32