Arduino NTC Thermistor Project for Beginners: Measure Temperature Accurately
Project Overview
This beginner-friendly project demonstrates how to use an NTC Thermistor with Arduino to measure and display temperature in Celsius. The NTC thermistor is a temperature sensor that changes its resistance with temperature, making it suitable for accurate temperature measurements.
Project Goals for Arduino NTC Thermistor
- Learn how to connect an NTC Thermistor to Arduino for temperature measurement.
- Use a voltage divider circuit to read temperature changes from the NTC thermistor.
- Understand how to calculate temperature from the NTC thermistor readings using the Beta value method.
Required Components for Arduino NTC Thermistor Project
Here’s a list of components needed to build this project:
| Component | Description | Link |
|---|---|---|
| Arduino Uno | Main microcontroller board | Buy on Amazon |
| NTC Thermistor (10k) | Temperature sensor with 10k nominal resistance | Check Availability |
| 10k Ohm Resistor | Used in the voltage divider circuit | Check Availability |
| Jumper Wires | Connects components to Arduino | Buy on Amazon |
| Breadboard | For prototyping connections | Buy on Amazon |
What is an NTC Thermistor?
The NTC Thermistor (Negative Temperature Coefficient) is a temperature sensor whose resistance decreases as temperature increases. It is commonly used in temperature measurement and control applications. The thermistor is part of a voltage divider circuit, which allows Arduino to read temperature variations as changes in voltage.
NTC Thermistor Pinout Overview
| Pin | Description |
|---|---|
| Lead 1 | Connected to 5V via the voltage divider resistor |
| Lead 2 | Connected to the analog input (A0) on Arduino |
Circuit Connection for NTC Thermistor with Arduino
Follow these connections to set up the NTC Thermistor with Arduino:
| Component | Arduino Pin | Details |
|---|---|---|
| Thermistor Lead 1 | 5V via 10k resistor | Connected to power through the voltage divider |
| Thermistor Lead 2 | A0 | Analog input to Arduino |
| 10k Resistor | Between Thermistor Lead 1 and 5V | Forms the voltage divider |
| GND | GND | Ground connection |
How the Circuit Works
The NTC Thermistor changes its resistance based on temperature. It is part of a voltage divider circuit that outputs a variable voltage to the Arduino’s analog input. The Arduino reads this voltage and calculates the temperature in Celsius using the Beta value method.
Arduino Code for NTC Thermistor
This code reads the resistance of the NTC Thermistor and calculates the temperature in Celsius using the Beta value formula. Copy and upload this code to your Arduino Uno.
/*!
* @file Arduino_NTC_Interface.ino
* @brief Interfacing NTC Thermistor With Arduino
*/
#define ntc_pin A0 // Pin connected to the voltage divider
#define vd_power_pin 2 // 5V for the voltage divider
#define nominal_resistance 10000 // Nominal resistance at 25⁰C
#define nominal_temperature 25 // Temperature for nominal resistance (25⁰C)
#define sampling_rate 5 // Number of samples
#define beta 3950 // Beta coefficient of the thermistor
#define Rref 10000 // Resistor value in voltage divider
int samples = 0;
void setup() {
pinMode(vd_power_pin, OUTPUT);
Serial.begin(9600); // Initialize serial communication at 9600 baud rate
}
void loop() {
uint8_t i;
float average;
samples = 0;
// Take voltage readings from the voltage divider
digitalWrite(vd_power_pin, HIGH);
for (i = 0; i < sampling_rate; i++) {
samples += analogRead(ntc_pin);
delay(10);
}
digitalWrite(vd_power_pin, LOW);
average = samples / sampling_rate;
Serial.println("\n\nADC Reading: " + String(average));
// Calculate NTC resistance
average = 1023 / average - 1;
average = Rref / average;
Serial.println("Thermistor Resistance: " + String(average) + " ohms");
// Calculate temperature using Beta formula
float temperature;
temperature = average / nominal_resistance;
temperature = log(temperature);
temperature /= beta;
temperature += 1.0 / (nominal_temperature + 273.15);
temperature = 1.0 / temperature;
temperature -= 273.15;
Serial.println("Temperature: " + String(temperature) + " *C");
delay(2000);
}
Steps to Upload Arduino Code
- Connect your Arduino to the computer using a USB cable.
- Open the Arduino IDE and paste the code into a new sketch.
- Select the correct board (e.g., Arduino Uno) and port from the "Tools" menu.
- Click the "Upload" button to transfer the code to the Arduino.
Check Output for NTC Thermistor
- Open the Serial Monitor (Ctrl + Shift + M) after uploading the code.
- The calculated temperature will be displayed in the Serial Monitor in Celsius.
- Observe the temperature change by touching the thermistor or using a heat source.
Troubleshooting Tips for NTC Thermistor
- No Readings in Serial Monitor: Check the wiring and ensure the thermistor is correctly connected.
- Incorrect Temperature Values: Verify the Beta value and nominal resistance of the thermistor used.
- Inconsistent Readings: Ensure stable connections and avoid noise interference.
Suggestions for Beginners
Start by testing the NTC Thermistor to understand its behavior with temperature changes. Once you’re comfortable with the readings, try integrating it into more complex temperature monitoring projects.
Recommended Book for Learning Arduino
Arduino Programming for Absolute Beginners - This book provides easy, step-by-step instructions, making it ideal for beginners who want to learn Arduino programming.
For more Arduino tutorials, visit MechatronicsLab.net, where you’ll find resources on Arduino, ESP8266, ESP32, and Raspberry Pi.
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