How to Use mlx90614: Examples, Pinouts, and Specs

The MLX90614 is a contactless infrared (IR) temperature sensor that provides a digital output corresponding to the temperature of the object it is pointed at. This sensor is manufactured by Melexis and is designed for non-contact temperature measurements in various applications, including industrial controls, automotive systems, medical equipment, and home appliances.

• Industrial Systems: Monitoring temperatures in machinery and processes.
• Automotive: HVAC climate control and engine cooling systems.
• Medical Equipment: Non-contact thermometers for patient monitoring.
• Consumer Electronics: Home appliances like microwave ovens and cooktops.
• DIY Projects: Integration with microcontrollers like Arduino for hobbyist projects.

• Supply Voltage (Vdd): 3.3V to 5V
• Measurement Range: -70°C to +380°C for object temperature
• Field of View (FOV): 90° typical
• Resolution: 0.02°C
• Accuracy: ±0.5°C for ambient temperature; ±1°C for object temperature
• Interface: I2C-compatible digital interface

1. Power Supply: Connect the Vdd pin to a 3.3V or 5V power supply.
2. Ground: Connect the GND pin to the ground of the power supply.
3. I2C Communication: Connect the SDA and SCL pins to the I2C data and clock lines of your microcontroller.

• Power Supply: Ensure that the power supply is within the specified voltage range.
• I2C Pull-up Resistors: Typically, 4.7kΩ pull-up resistors are required on the SDA and SCL lines.
• Filtering: Place a capacitor close to the Vdd pin to filter out power supply noise.
• Field of View: Be aware of the sensor's FOV to ensure accurate temperature readings of the intended object.
• Calibration: For critical applications, calibrate the sensor in the specific environment where it will be used.

#include <Wire.h>
#include <Adafruit_MLX90614.h>

Adafruit_MLX90614 mlx = Adafruit_MLX90614();

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

void loop() {
  Serial.print("Ambient = "); Serial.print(mlx.readAmbientTempC()); 
  Serial.print("*C\tObject = "); Serial.print(mlx.readObjectTempC()); Serial.println("*C");
  delay(500);
}

• #include <Wire.h>: Includes the I2C library for communication.
• #include <Adafruit_MLX90614.h>: Includes the library for the MLX90614 sensor.
• Adafruit_MLX90614 mlx: Creates an instance of the MLX90614 class.
• Serial.begin(9600): Initializes serial communication at 9600 baud rate.
• mlx.begin(): Initializes the sensor.
• mlx.readAmbientTempC(): Reads the ambient temperature in Celsius.
• mlx.readObjectTempC(): Reads the object temperature in Celsius.
• delay(500): Pauses the loop for 500 milliseconds.

• Inaccurate Readings: Ensure that the sensor is not exposed to sudden temperature changes and that the FOV is correctly aligned with the target.
• No Data on I2C: Check the wiring, ensure pull-up resistors are installed, and verify that the correct I2C address is being used.

• Power Supply Issues: Verify that the power supply is stable and within the specified voltage range.
• I2C Communication: Use an I2C scanner sketch to confirm that the sensor is detected on the I2C bus.
• Sensor Placement: Adjust the sensor's position to avoid interference from surrounding objects.

Q: Can the MLX90614 measure the temperature through glass? A: No, the sensor cannot measure through glass as it blocks IR radiation.

Q: Is the MLX90614 waterproof? A: The sensor itself is not waterproof. It requires additional protection if used in a moist environment.

Q: How can I calibrate the MLX90614? A: Calibration should be done against a known temperature reference in the same environmental conditions as the intended application.

Q: What is the I2C address of the MLX90614? A: The default I2C address is 0x5A. However, it can vary with different versions of the sensor.

This documentation provides a comprehensive guide to the MLX90614 IR temperature sensor, ensuring users can effectively integrate and utilize this component in their projects.