The sensor is configured and read from over a 2-wire SMBus interface - very similar, and nearly functionally equivalent to I 2C.
Once you've set up an SMBus interface, you can later configure the MLX90614 to produce a pulse-width modulated (PWM) signal representing the measured temperature(s). The two-wire SMBus interface is the primary means for communicating with the IR sensor. The MLX90614 supports two interfaces - though you'll need one to access the other.
If you're one foot away from an object (30.48cm), the sensing area will be two feet (60.96cm). That means for every 1cm you move away from an object, the sensing area grows by 2cm. The MLX90614BAA has a relatively wide field-of-view angle: 90°. The MLX90614's field of view is cone-shaped - its sensing area is very narrow if it's near the object, but gets increasingly wider as it moves farther away. It determines the relationship between the distance from an object and the area of space being observed. Spot DiameterĪn IR thermometer's field-of-view (FOV) is a critical property to be aware of. We're carrying the MLX90614BAA, which is rated for a 3V operating voltage with a single infrared sensor and an internal filter. The different sensor options vary by operating voltage, number of IR thermopiles, and whether they filter inside our outside the sensor. There are many varieties of the MLX90614 out there, each suffixed with three letters. The object temperature measurements can range from -70 to 382.2 ☌ (-94 to 719.96 ☏), while the ambient temperature reading ranges from -40 to 125 ☌.īoth the ambient temperature and object temperatures have a resolution of 0.02 ☌. The ambient can be useful to calibrate the data, but the real meat of our readings will come from the object temperature measurement. The object temperature is the non-contact measurement you'd expect from the sensor, while the ambient temperature measures the temperature on the die of the sensor. The MLX90614 produces two temperature measurements: an object and an ambient reading. MLX90614 pinout - note the notch to help indicate pin 1 (from datasheet page 5). If you're unfamiliar with these topics, consider checking out those tutorials first: This tutorial builds on a few lower-level concepts. MLX90614 Arduino Library - Installing and using the SparkFunMLX90614 infrared thermometer library.
Arduino thermometer how to#
Hardware Hookup - How to create a circuit around the bare sensor and/or interface with the evaluation board.Evaluation Board Overview - A quick rundown of the evaluation board's features.MLX90614 Overview - A brief introduction to IR thermometer theory and the MLX90614's specifications and interfaces.The tutorial is split into the following sections: It dips into theory, paraphrases some datasheet tables, demonstrates example circuits, and introduces a new Arduino library. It covers hookup of both the bare sensor (to an Arduino) and the SparkFun MLX90614 Evaluation Board. This tutorial aims to quickly familiarize you with the MLX90614 IR thermometer and demonstrate how to interface it with an Arduino. Using SMBus - an I 2C-like interface - to communicate with the chip means you only need to devote two wires from your microcontroller to interface with it. The IR Thermometer Evaluation Board is equipped with an MLX90614-ABB - a simple-to-use, but very powerful single-zone infrared thermometer, capable of sensing object temperatures between -70 and 380☌.
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