Python, PHP, MySQL, C++ , Arduino, RFID (MFRC522), GSM (Sim800L).
The payments are received on the server, and transmitted via GSM to the devices on-site. On presentation of the RFID card of an account holder, the relays activate the machine, while Hall sensors measure the current consumed to charge the right amount.
Picture of the stripped down prototype:
Last updated: July 2020