This project came out of necessity. With the amount of members we have, it made more sense to make an automated door access system, than to give everyone keys. We originally used an Arduino for the last 2 years, but we wanted to be able to control the database of users easier, our current setup wrote the users to the eeprom of the Arduino. We were thinking about using an ethernet module to talk with a server on our network but if our network had issues that would prevent someone from entering. The small footprint of the Pi makes it a better choice than to run a server fulltime. Our modest server burns through around $200 a year worth of electricity. By comparison a Raspberry Pi consumes about $3 per year. With the Raspberry Pi we could now have ethernet capabilities, could store its own database, gpio pins , video output and more.
Starting the project I needed to figure out how to interface a RFID reader with the Pi. I wanted to interface it with the UART pins but due to time constraints I ended up using a sparkfun USB adapter with my Innovations ID-20 RFID reader. The only thing I has to do was monitor the USB in /dev and receive the RFID tag ID when someone scanned their card. To do this I used python script that monitored serial connection on /dev/ttyUSB0 the base of the script which I have posted to my github account and used a sqlite3 database to verify if the card scanned was a valid member, if so it would trigger the door. Also used a RGB LED to notify if the card was good or not.