MLX90615

Arduino library for the Melexis MLX90615 non-contact IR temperature sensor.

Features

• Read object (IR) and ambient (die) temperature
• Temperature output in Kelvin, Celsius, or Fahrenheit
• Configure emissivity (0.1–1.0)
• Configure IIR digital filter coefficient
• SMBus communication with CRC-8 (PEC) validation

Hardware

MLX90615 Pin	Arduino (Uno)
SDA	A4
SCL	A5
VDD	3.3V
GND	GND

Note: The MLX90615 operates at 3.3V. Use a logic-level shifter if connecting to a 5V Arduino.

Installation

1. Download or clone this repository.
2. Copy the folder into your Arduino libraries/ directory.
3. Restart the Arduino IDE.

Usage

Basic temperature reading

#include <Wire.h>
#include "MLX90615.h"

MLX90615 sensor; // uses default I2C address 0x5B

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

void loop() {
    double objTemp = sensor.readTemp(MLX90615::MLX90615_SRCO, MLX90615::MLX90615_TC);
    double ambTemp = sensor.readTemp(MLX90615::MLX90615_SRCA, MLX90615::MLX90615_TC);

    Serial.print("Object: "); Serial.print(objTemp); Serial.println(" C");
    Serial.print("Ambient: "); Serial.print(ambTemp); Serial.println(" C");
    delay(1000);
}

Custom I2C address

MLX90615 sensor(0x5B); // explicit address

Temperature units

sensor.readTemp(MLX90615::MLX90615_SRCO, MLX90615::MLX90615_TK); // Kelvin
sensor.readTemp(MLX90615::MLX90615_SRCO, MLX90615::MLX90615_TC); // Celsius (default)
sensor.readTemp(MLX90615::MLX90615_SRCO, MLX90615::MLX90615_TF); // Fahrenheit

Emissivity

sensor.setEmissivity(0.95); // set emissivity (0.1–1.0, default 1.0)
float e = sensor.getEmissivity(); // read back current emissivity

IIR filter

sensor.setIIR(1); // 1 = IIR bypassed (default), 7 = strongest filtering
uint8_t iir = sensor.getIIR();

API Reference

Method	Description
begin()	Initialize the sensor and I2C interface
readTemp(src, unit)	Read temperature from MLX90615_SRCO (object) or MLX90615_SRCA (ambient)
setEmissivity(float)	Set emissivity coefficient (0.1–1.0)
getEmissivity()	Get current emissivity coefficient
setIIR(uint8_t)	Set IIR filter coefficient (1–7)
getIIR()	Get current IIR filter coefficient
readEEprom(addr)	Read a raw 16-bit EEPROM register
writeEEprom(addr, data)	Write a raw 16-bit EEPROM register
readRAM(addr)	Read a raw 16-bit RAM register

Error Handling

After any operation, R/W errors are stored in an internal bitmask. Error flags are defined in MLX90615.h:

Flag	Value	Meaning
MLX90615_NORWERROR	0x00	No errors
MLX90615_RXCRC	0x10	CRC mismatch on received data
MLX90615_INVALIDATA	0x20	Data out of valid range
MLX90615_EECORRUPT	0x40	EEPROM may be corrupted

License

MIT