smart card | CuVoodoo

reversing washing machine payment cards:
To use the washing machines in my apartment complex you need to pay using a rechargeable contact card. I was curious to find out how it works. It turns out it's an I²C EEPROM in a card. By recording the communication between the card and the machine I figured out where and how the credit value is stored. Now I can read and write the value on cards using a Raspberry Pi or simple micro-controller, but also program my own cards to work with the machines.