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.

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  1. Pingback: Electronics-Lab.com Blog » Blog Archive » RFID reader based on PIC microcontroller

  2. Hi friend thank you for project but ,Do a full circuit I did not see the value of referance voltage what is the vref voltage value

  3. Did you read this at the end of article? “Currently, I set the Vcc to 10V, 5V is extracted from Vcc using a simple 78L05 voltage regulator. The Vref is set to half of logic voltage supply at 2.5V, this is accomplished using a simple resistor divider consists of two 4.7k resistor.”

  4. Hi friend my english bad I don’t under stand what is your antenna size I’m under stand x=y=6cm, h=1cm b=0.3cm and number turns of coil is 34 are these values true? especially number turns of coil,Because I tried this application with your size and I can not run ,I’m looking for a problem and I’m not sure from coil size because my antenna thin from your antenna I’m waiting your reply ,already thanks

  5. circut diagram of rfid with pic microcontroller

  6. I’m senthil a final year electronic from Malaysia.I’m currently completing a basic RFID based project and in desperate need of your help.
    I found you RFID -D-I-Y online and tried to understand and reproduce it in my project.Could you please clarify me certain things?

    * The Micro controller is there ONLY to produce a PWM.
    * The inductor coil does not effect the workability of the project.

    Is it possible for you to show me a simple circuit the would detect an RFID card when placed near?.When the card is placed nearby, all needeed is an output signal.
    Example: Card detect then led lights up.

    Please do reply asap as i’m running out of time.
    Thanking you in advance.

  7. may i know the type of microcontroller exactly suits this project and also i think this is suitably like electrnic attendance system ,if so can i have the data sheet for this project thanku

  8. i’ve made a reader based on microchip microid fsk reader design guide.i’ve problem testing the circuit and how to interface the reader to the pc??can someone help me…

  9. hi assist me i do not anderstent how does the circuit function.

  10. im having same problem like raj. could you please give the basic circuit for rfid to detect the belonging?

    thanks a lot

  11. this circuit will help me..i want to know the materials used for this circuit..please forward to me


  12. Abdul Subhan Bintory

    Dear Sir,

    Good Day,
    Kindly give me access password to me i need to make project

    Thanks and regards,

    A.Subhan bintory

  13. Hi all
    how to have login access? Anyone know how to register or have source documentation?

    thankyou for reply

  14. Hi,

    I am an electronic hobbyist…Need some help.
    I have nail art led simple device..it is based on 13.56Mhz NFC concept.
    I just need my led to light up with a simple circuit that generates NFC energy. NO data reading is involved.
    Just a simple circuit just to light up the nail art led stickers when it is very close by.. the most about 5 cm

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