RFID lock project

RFID lock project is based on PIC16F84 microcontroller. Device can read 125kHz read only RFID tag cards. Device can work in two modes: toggle lock and pulse. In toggle mode lock changes its state when card is moved near reader while pulse mode lock changes its state for some period and comes back to its previous state. Microcontroller EEPROM memory stores 12 byte long IDs of RFID tags. It is possible to store multiple card IDs, where number is limited only to EEPROM size. Whole project description is Bosnian language – well circuit language is same for all 🙂 Continue reading

RFID reader based on PIC microcontroller

RFID cards are commonly used in many areas like access control, security, and for other identification purposes. One of simplest cards to read are HID ISOProx that don’t use any encryption. Their carrier frequency is 125 kHz.   Hardest part in this reader project is the reader itself as it has to power the tag with magnetic field and sense the transmitted signal. For this series resonance of 150 kHz circuit – antenna is used. Signal from antenna is passed through low pass and band pass circuits and then to PIC comparator, where RFID FSK pulses are detected and decoded. Latest ASM source can be seen here. Probably RFID reader could use more advanced microcontroller than PIC16F628A for more efficient signal reading by using interrupt based compare capture module as this one already uses it for 150 kHz carrier signal generation. Continue reading