Budget Thermal Imaging with the Raspberry Pi 2
Channel: Charles Werbick
Date: 2015-04-24

Short video demo of Thermography using the Raspberry Pi 2 and the Melexis MLX90620 16x4 thermopile array.

Parts Used: 
 - Raspberry Pi 2
 - small HDMI monitor  or PiTFT
 - Raspberry Pi Camera
 - MLX90620 16x4 thermopile array
 - 1N4001 diode

The MLX sensor is bolted to the raspberry pi camera and they are pointed in the same direction. The sensor is I2C and will work on 3.3V, but runs best on ~2.6V. So the 1N4001 diode is used to lower the voltage to the positive pin of the MLX90620. This sensor also requires 'repeat starts'. So the BCM2835 library is used instead of the kernel I2c device driver.

Software consists of two programs-
 mlxd - a simple user space device driver/daemon written in C that reads the sensor and writes the temperature array to a FIFO
 mlxview.py - a demo script that access the fifo and the pi camera, generates a color heat map from the array and overlays it on the camera preview.
 
Acknowledgements - The daemon portion of this project uses code by Mike Strean from his PIIR project - https://github.com/strean/piir  

Source code for this project - 
https://github.com/alphacharlie/mlxd