Update 28th April 2020: The firmware has been updated to v1.1, with lots of new features and improvements!
This is a simple, yet very useful, IR (infrared) thermal camera project for the Odroid Go handheld ESP32 system. It allows saving of data to an SD card as well as having a Bluetooth interface to wirelessly get data off the camera to a computer, tablet or mobile phone. It's based on the MLX90640 32x24 pixel infrared thermal array modules that you can get relatively inexpensively many places online. Here's a short list of some of it's features:
- Onscreen display of the IR image, with a movable cursor to let you query the temperature for any single pixel (press up, down, left and right on the + control to move the cursor).
- A range of colour maps, which are easily added to in the Arduino code.
- A zoom button so you can switch the IR image to/from full-screen mode.
- Saving of data to the SD card on your ODroid GO in text CSV format for later analysis.
- A fever screening colour map, which shows temperatures above 36C in red to indicate when checking for a fever may be necessary (not for medical diagnosis).
- In fever checking mode IR images with temperatures above 36C are indicated by an audible beep, to help with rapid screening of your family and friends.
- An on-screen battery indicator, so you know when to recharge your GO.
- A Bluetooth interface that lets you take full control of the IR camera, including transferring the IR data to a PC as ASCII text or binary data.
- 3D printing STL files to make a forward-facing or rear-facing case to protect your thermal IR module.
Below is a photo of the project in action on an Odroid GO:
There are two ways to use the thermal camera code. The really simple way is to go to the 'FW file' folder and copy the 'goircam.fw' file to the firmware folder on your Odroid Go SD card. Then when you turn the Go on with the B button held down you should get an option to load the camera firmware. Obviously you'll need the camera built and attached for the firmware to run.
The more advanced way is for people who want to use the Arduino IDE to edit or build the firmware. To do that just use the files in the 'Arduino code' folder as you would do for code in any other Arduino project you have. All of the details are available on the Odroid Go website for setting up the Arduino IDE for the Go, so I won't cover it here.
If you're using the Arduino IDE method and want to create a firmware file, as described on the Go site, the graphics for use with the MKFW utility are included in the 'Graphics' folder.
Building the module is very simple, as it uses just the MLX90640 module, with wires for ground, VCC, SCL and SDA (so just power and I2C). According to the Go wiki the header pinout is as follows, so you can wire the module easily even just using some wires and a breadboard.
| Header Pin | Function |
|---|---|
| 1 | GND |
| 4 | SDA |
| 5 | SCL |
| 6 | VCC |
Once you've got things wired up and tested, the simplicity of the circuit makes it very simple to solder up some header pins on a piece of veroboard to make a more robust connector for the Odroid Go header sockets. Below is a photo of how I did that. I put the header pins on top of the veroboard and soldered the wires to the track on the back, which meant the wires didn't obstruct the connection, although you could just use a bigger piece of veroboard too.
The 'Case 3D model' folder includes files I used to make 3D printed enclosures. The STL files are designed for the Pimoroni MLX90640 module I used. If that doesn't work for your needs, or the MLX90640 module you have, the OpenSCAD files are included so you can make a custom version. By cutting the veroboard to the right size the IR module should fit perfectly into the back of the enclosure, leaving the header pins properly positioned as shown in the front-facing example photo below. The veroboard was glued in, and it's necessary to check the pins as the glue goes off to make sure they stay perpendicular to the enclosure.
Below are some links that may be useful if you decide to build this project.
The Odroid Go Wiki is a useful resource for all Go things: https://wiki.odroid.com/odroid_go/odroid_go
The Wiki page for a 16x2 I2C LCD project contains details of how to connect an I2C module to the Go header: https://wiki.odroid.com/odroid_go/arduino/09_16x2lcd_i2c
The front facing 3D printed case can also be downloaded from Thingiverse: https://www.thingiverse.com/thing:3648653
And the rear facing 3D printed case can also be downloaded from MyMiniFactory: https://www.myminifactory.com/object/3d-print-odroid-go-thermal-infrared-ir-camera-ideal-for-covid-coronavirus-screening-122446