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The wall clock and voting tabulator is built using a RaspberryPi to create a WiFi Access Point for the voting boxes. This then communicates with an Arduino Mega 2560 that runs the display and tabulates votes. The date and time are kept by a DS3231 real-time clock module.
The available commands on the keypad are:
The source code for the clock is in the attached file. In addition, there are a number of third-party libraries used. The DS3231 library can be found here. The other libraries are standard libraries and most can be installed directly within the Arduino IDE.