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Wiegand 4 bit, 8 bit, 24 bit, 26 bit, 32 bit and 34 bit library for Arduino

The Wiegand interface is a de facto standard commonly used to connect a card reader or keypad to an electronic entry system. Wiegand interface has the ability to transmit signal over long distance with a simple 3 wires connection. This library uses interrupt pins from Arduino to read the pulses from Wiegand interface and return the code and type of the Wiegand.

NON Standard Bit Length

This library was designed to decode standard Wiegand protocol with 1 START bit, 1 STOP bit and bit length stated in the title. For multi-bit length protocol, please try Wiegand NG Multi Bit Wiegand Library for Arduino.


The following are needed

  • Arduino - Any ATMEGA328 compatible board should work.
  • Wiegand RFID Reader - The code was written for this reader however customers reported working with HID compatible readers.
  • DATA0 of Wiegand connects to Arduino PIN 2 and DATA1 of Wiegand connects to Arduino PIN 3


Create a folder named Wiegand in Arduino's libraries folder. You will have the following folder structure:

cd arduino/libraries
git clone Wiegand

Arduino Sketch

alt text

Execute Arduino IDE, select Example-->Wiegand-->WiegandTest


#include <Wiegand.h>


void setup() {
	// default Wiegand Pin 2 and Pin 3 see image on
	// for non UNO board, use wg.begin(pinD0, pinD1) where pinD0 and pinD1 
	// are the pins connected to D0 and D1 of wiegand reader respectively.

void loop() {
		Serial.print("Wiegand HEX = ");
		Serial.print(", DECIMAL = ");
		Serial.print(", Type W");


softwarefoundry added

Francesco Uggetti (ugge75) improved this version of library to support multiple readers for ATMEGA2560. Please check out his version of multiple wiegand readers library here

Apollon77 improved interrupt safety and removed sysTick from global

paulfurley added 4 bit code

PaulStoffregen added Use digitalPinToInterrupt on newer Arduino software, if present

tholum Simpler Instructions

zanhecht Recognize 24- and 32-bit

luckymallari Simplified begin(D0, D1) for ESP(8266/32) devices.

Written by JP Liew

Project home:

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.


Wiegand 26 and Wiegand 34 Protocol Library for Arduino



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