This software shows a 5-minute countup (need to fix it to countdown) timer in the terminal and sends information to Arduino turn on/off the red or green lights.

To make it work:

• Connect a red light to digital port 4 and green to digital 2 of your Arduino;
• Upload countdown.ino to your Arduino;
• Plug your Arduino in your computer using a USB cable;
• Run python countdown.py

You need to install pyserial. To do so, execute:

pip install pyserial

or:

aptitude install python-serial

(If do you use Ubuntu, execute sudo apt-get install aptitude and be happy)