mlx90640-library

MLX90640 library functions

Raspberry Pi Users

** EXPERIMENTAL **

This port uses either generic Linux I2C or the bcm2835 library. Upon building, the mode is set with the I2C_MODE property, i.e. make I2C_MODE=LINUX or make I2C_MODE=RPI. The default is LINUX, without the need for the bcm2835 library or root access.

Generic Linux I2C Mode

Make sure the Linux I2C dev library is installed:

sudo apt-get install libi2c-dev

To get the best out of your sensor you should modify /boot/config.txt and change your I2C baudrate.

The fastest rate recommended for compatibility with other sensors is 400kHz. This is compatible with SMBus devices:

dtparam=i2c1_baudrate=400000

This will give you a framerate of - at most - 8FPS.

If you're just using the MLX90640 and, for example, the 1.12" OLED, you can safely use 1MHz:

dtparam=i2c1_baudrate=1000000

This will give you a framerate of - at most - 32FPS.

Now build the MLX90640 library and examples in LINUX I2C mode:

make clean
make I2C_MODE=LINUX

BCM2835 Library Mode

To use the bcm2835 library, install like so:

make bcm2835

Or, step by step:

wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.55.tar.gz
tar xvfz bcm2835-1.55.tar.gz
cd bcm2835-1.55
./configure
make
sudo make install

Dependencies

libav for video example:

sudo apt-get install libavutil-dev libavcodec-dev libavformat-dev

SDL2 for sdlscale example:

sudo apt install libsdl2-dev

Building

After installing the dependencies, you can build the library. Build-modes are:

• make or make all: build the library and all dependencies. Default is to use standard linux I2C-Drivers, specify Raspberry Pi driver with make I2C_MODE=RPI
• make examples: only build examples, see below
• sudo make install: install libraries and headers into $PREFIX, default is /usr/local

Afterwards you can run the examples or build the python binding, see readme in the subfolder. If you built the examples or library using the native bcm2835 I2C-Driver, you need to run all applications and examples as root. Hence, sudo examples/<exampleame> for one of the examples listed below, or without sudo when using the standard Linux driver.

Examples

fbuf

make examples/fbuf
sudo examples/fbuf

This example uses direct-to-framebuffer rendering and black-blue-green-yellow-red-purple-white false colouring.

If you gave issues with the output image, set "IMAGE_SCALE" to a smaller number.

interp

make examples/interp
sudo examples/interp

This example uses direct-to-framebuffer rendering and black-blue-green-yellow-red-purple-white false colouring.

It also has 2x bicubic resize filter.

If you have issues with the output image, set "IMAGE_SCALE" to a smaller number.

test

make examples/test
sudo examples/test

This example draws out to the console using ANSI colours and the full block char.

To see the actual temperature values, change "FMT_STRING" from the block char to the float format.

step

make examples/step
sudo examples/step

Attempt to run in step by step mode (experimental)

sdlscale

Displays the MLX90640 sensor full-screen using hardware acceleration in SDL2.

Hit Spacebar to change from aspect-ratio correct to full-screen-stretched modes.

Hit Escape to exit.

make examples/sdlscale
sudo examples/sdlscale

Requires SDL2 libraries:

sudo apt install libsdl2-dev

On Raspbian Lite you may wish to build SDL2 from source with X support disabled to avoid pulling in ~200MB of dependencies. Before configuring/compiling ensure you have libudev-dev installed for input support.