How to get Values from MLX90614 IR Thermometer

The MLX90614 IR Thermometer breakout from rhydoLABZ is an InfraRed thermometer for non contact temperature measurements. We have designed this product to be compatible in its design with Sparkfun’s Evaluation breakout. We redesigned the circuit with level conversion buffer gates for added reliability. The sensor is interfaced with an ATmega328 onboard, running at 3.3V/5V with STK500 (Arduino) 8MHz bootloader loaded. The ATmega328 can be programmed over the FTDI/CP2102 basic interface and the Arduino environment. The module replaces the use of arduino board and breadboard connections. The GPIO pins taken out help you to interface some more devices with evaluation board is added advantage. We uses I2C protocol for communication with MLX90614.


  • MLX90614 IR sensor
  • Low Cost and compact
  • ATMega328 (8MHz STK500 – Arduino boot loader)
  • Small size, low cost Easy to integrate
  • Factory calibrated in wide temperature range:  High accuracy of 0.5°C over wide temperature range
    • -40 to 125 ̊C for sensor temperature
    • -70 to 380 ̊C for object temperature.
  • Supports 3V and 5V logic levels, jumper selectable
  • Loaded with firmware, temperature output in degree Celsius
  • Provision to update the firmware
  • Can be used for standalone function or along with host controller
  • Compatible with Sparkfun IR Evaluation Board
  • Power and status LEDs 
  • High Quality PTH PCB
  • Automotive grade

Pin out

Hardware Overview

The user can conveniently interface our breakout either with 3V3 or 5V logic levels, as selected by the PCB jumper provided at the bottom side as shown below. It has on-board level converter, so no need of any external level shifting circuitry. This ensures module safety while working with 5V devices.

On-board reset switch (RST) resets the microcontroller. There are two LEDs, one of them(red) indicates on-board power(PWR) and other(green) is user programmable status LED(marked as STS).

The MLX90614 evaluation board is a standalone device with its own atmega328 microcontroller with STK500 (Arduino) 8MHz bootloader loaded. The breakout is pre-programmed to read MLX90614 sensor data and output the ambient temperature serially at 9600 bps. If you want to view the temperature output, then connect the FTDI/CP2102 board with the evaluation board. Open any serial terminal devices of your choice and connect with the detected com  port and 9600 bps. You can see the temperature readings in degree Celsius on the window, e.g; T036.00C. The status LED is programmed to blink after each serial data out. The output format is shown below.

Are you crazy with your own experiments? You have an option to upload your own program to the evaluation board. The atmega328 is already bootloaded so you can program it serially with the help of USB to TTL converter. To program the evaluation board, select board as Arduino PRO or PRO mini and processor as Atmega328 (3.3 V, 8 MHz). The breakout pins such as analog, UART, SPI and power help you to add some more glam to your new projects. In addition to on-board thermometer you can add few of external sensors via these pins. ATmega’s SPI interface is available on the ICSP header. You can download the sample code and adafruits MLX90614 library from Github. To add the library to your Arduino sketchbook, open the IDE, navigate to Sketch > Include Library > Add .ZIP Library… and select the ZIP folder you just downloaded.



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