Connect LED matrix to Raspberry pi

For a long time, an 8 * 8 LED array was in the box complete with a MAX7219 chip for its control, a 10 kΩ resistor, a 100 nF ceramic capacitor and a 10 μF electrolytic capacitor, a circuit board and several connectors. Kit is obtained as in the photo . Finally, I collected my strength and decided to connect it.

I was looking for a long time how to connect such a kit to raspberry and an example of a C + program, but I did not find it, but there are many examples for Arduino. It was possible to find only a sample code on python and configuration instructions , which, in the absence of the best, and used. And in this article I will tell in detail how to connect.

First, it is necessary to assemble this kit on a printed circuit board - everything is simple there, especially after reading the soldering instructions “soldering is simple . ”
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Getting Started Setting Raspberries

Check if SPI is enabled. To do this, enter in the terminal:

dmesg | grep spi 

It should get something like this:

 [ 8.581285] spi spi0.0: setting up native-CS0 as GPIO 8 [ 8.589797] spi spi0.1: setting up native-CS1 as GPIO 7 

If nothing is returned in response,
Check if we have SPI installed in / dev, for this we type in the terminal:

 ls -l /dev/spi* 

On the screen should get:

 crw-rw---T 1 root spi 153, 0 Jan 1 1970 /dev/spidev0.0 crw-rw---T 1 root spi 153, 1 Jan 1 1970 /dev/spidev0.1 

We connect our module to Raspberry:
VCC - to 5V raspberry
GND - to gnd
DIN (data in) - GPIO 10 (SPI MOSI)
CS (chip select) - GPIO 8 (SPI CS0)
CLK (clock) - GPIO 11 (SPI CLK)

On the other side of the module there are pins with similar designations - they are intended for the serial connection of modules.

Install the necessary programs to display information on the display
Download the library to work with the module:

 git clone https://github.com/rm-hull/max7219.git 

Install the necessary components:

 sudo apt-get install python-dev python-pip sudo pip install spidev sudo python setup.py install 

Run the existing example and check the operation of the module:

 sudo python examples/matrix_test.py 

A running line with the text from the example should appear on the display. The text can be changed, for this we edit the file with the command:

 nano examples/matrix_test.py 

The displayed text is shown in brackets after the device.show_message command.

An example of the display based on the idea dev_random :