MLX90614 is a very useful infrared thermometer (no contact needed) that gives you the average temperature reading of all objects in the view range. In addition to it`s principal temperature reading function, it can be used for movement or even presence detection. There are two ways of interfacing this sensor, through PWM communication or SMBus (TWI or I ²C) communication.
Click here to download the full size of the above Circuit.
I wasn`t able to get the first one working, so tried SMBus I ²C that is not easier to code but gives you some advantages over PWM. Through I ²C you can connect over 127 devices using just two Wiring pins and also, in this specific sensor (MLX90614) you get better resolution readings. Wiring comes with a special library for interfacing I ²C devices (wire library) but unfortunately this library is not compatible with MLX90614 because it doesn`t support the use of the repeated start function (if you want to read further about this issue check this link ). So, we are going to use the I ²Cmaster library that has been modified by the guys at bildr. blog for working properly with the Wiring board. The first thing that has to be done is to download and instal the the I ²Cmaster library. As I said before, were using a version modified by the guys at bildr. blog. Once you have the library installed, you can use the following setup diagram and code for reading temperature from one MLX90614 connected to the TWI pins (on the Wiring v1 board 0 (SCL) and 1 (SDA) and on Wiring S board 8 (SCL) and 9 (SDA). Both (diagram and code) are based on the Is it hot Arduino + MLX90614 IR Thermometer bildr. blog post. /* * Infrared Thermometer MLX90614 * by Jaime Patarroyo * based on `Is it hot Arduino + MLX90614 IR Thermometer` by bildr. blog * * Returns the temperature in Celcius and Fahrenheit from a MLX90614 * Infrared Thermometer, connected to...
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