Introduction

This repository implements a clock based on MAX7219 LED dot matrix display connected to the Raspberry PI via SPI protocol.

The provided code represents a small framework suitable for development of smart clock / display oriented applications. By inheriting Faces::Face base class, a new clock face can be easily added.

While the current code has only been tested on the Raspberry PI, it should work on any platform as long as appropriate Spi implementation is provided by implementing the Device::Spi interface.

Usage

Build

To build the code with CMake, run following commands:

mkdir build
cd build
cmake ..
make

Alternatively, to compile the code without the CMake, run:

make

Running in test mode

To run the program in the test mode:

touch test
./clock test

Running on Raspberry PI

To run the program on a Raspberry Pi, provide the path to device file for SPI (here assuming that the MAX7219 is connected to the first spi interface):

./clock /dev/spi0.0

Test mode

Development can also be done on a regular workstation without an actual hardware, as the contents of the display can also be dumped to the standard output. To enable this, pass "test" as a parameter instead of the actual device file. Make sure that the test file also exist, as all SPI commands byte stream will be dumped to this file. Example of the console output in test mode is given below.

-----X----XXX-----------X----X--
----XX---X---X---------XX---XX--
-----X---X---X---X----X-X----X--
-----X----XXX--------X--X----X--
-----X---X---X---X---XXXXX---X--
-----X---X---X----------X----X--
----XXX---XXX-----------X---XXX-
--------------------------------

Integration with external programs

The clock supports the "File" face, which loads text from plain text files and displays it in a scrolling manner. This allows for a simple integration with external tools. Weather clock face has been provided as an example. The weather data is first obtained from the openweathermap web api by the python script located in the "fetch" folder. The script will dump the output to the "tmp/weather" which is then read and displayed by the watch face (check main.cpp). To allow for continuous update of the weather data, the runner script could be added as a cronjob.

Before using the Weather script, API key and location needs to be set. To do so, copy the "fetch/env_example" file to "fetch/.env" and update the API key and location environment variables.