/*
* HID RFID Reader Wiegand Interface for Arduino Uno
* Written by Daniel Smith, 2012.01.30
* www.pagemac.com
*
* This program will decode the wiegand data from a HID RFID Reader (or, theoretically,
* any other device that outputs weigand data).
* The Wiegand interface has two data lines, DATA0 and DATA1. These lines are normall held
* high at 5V. When a 0 is sent, DATA0 drops to 0V for a few us. When a 1 is sent, DATA1 drops
* to 0V for a few us. There is usually a few ms between the pulses.
*
* Your reader should have at least 4 connections (some readers have more). Connect the Red wire
* to 5V. Connect the black to ground. Connect the green wire (DATA0) to Digital Pin 2 (INT0).
* Connect the white wire (DATA1) to Digital Pin 3 (INT1). That's it!
*
* Operation is simple - each of the data lines are connected to hardware interrupt lines. When
* one drops low, an interrupt routine is called and some bits are flipped. After some time of
* of not receiving any bits, the Arduino will decode the data. I've only added the 26 bit and
* 35 bit formats, but you can easily add more.
*/
#define MAX_BITS 100 // max number of bits
#define WEIGAND_WAIT_TIME 3000 // time to wait for another weigand pulse.
unsigned char databits[MAX_BITS]; // stores all of the data bits
unsigned char bitCount; // number of bits currently captured
unsigned char flagDone; // goes low when data is currently being captured
unsigned int weigand_counter; // countdown until we assume there are no more bits
unsigned long facilityCode=0; // decoded facility code
unsigned long cardCode=0; // decoded card code
// interrupt that happens when INTO goes low (0 bit)
void ISR_INT0()
{
//Serial.print("0"); // uncomment this line to display raw binary
bitCount++;
flagDone = 0;
weigand_counter = WEIGAND_WAIT_TIME;
}
// interrupt that happens when INT1 goes low (1 bit)
void ISR_INT1()
{
//Serial.print("1"); // uncomment this line to display raw binary
databits[bitCount] = 1;
bitCount++;
flagDone = 0;
weigand_counter = WEIGAND_WAIT_TIME;
}
void setup()
{
pinMode(13, OUTPUT); // LED
pinMode(2, INPUT); // DATA0 (INT0)
pinMode(3, INPUT); // DATA1 (INT1)
Serial.begin(9600);
Serial.println("RFID Readers");
// binds the ISR functions to the falling edge of INTO and INT1
attachInterrupt(2, ISR_INT0, FALLING);
attachInterrupt(3, ISR_INT1, FALLING);
weigand_counter = WEIGAND_WAIT_TIME;
}
void loop()
{
// This waits to make sure that there have been no more data pulses before processing data
if (!flagDone) {
if (--weigand_counter == 0)
flagDone = 1;
}
// if we have bits and we the weigand counter went out
if (bitCount > 0 && flagDone) {
unsigned char i;
Serial.print("Read ");
Serial.print(bitCount);
Serial.print(" bits. ");
// we will decode the bits differently depending on how many bits we have
// see www.pagemac.com/azure/data_formats.php for mor info
if (bitCount == 35)
{
// 35 bit HID Corporate 1000 format
// facility code = bits 2 to 14
for (i=2; i<14; i++)
{
facilityCode <<=1;
facilityCode |= databits[i];
}
// card code = bits 15 to 34
for (i=14; i<34; i++)
{
cardCode <<=1;
cardCode |= databits[i];
}
printBits();
}
else if (bitCount == 26)
{
// standard 26 bit format
// facility code = bits 2 to 9
for (i=1; i<9; i++)
{
facilityCode <<=1;
facilityCode |= databits[i];
}
// card code = bits 10 to 23
for (i=9; i<25; i++)
{
cardCode <<=1;
cardCode |= databits[i];
}
printBits();
}
else {
// you can add other formats if you want!
Serial.println("Unable to decode.");
}
// cleanup and get ready for the next card
bitCount = 0;
facilityCode = 0;
cardCode = 0;
for (i=0; i<MAX_BITS; i++)
{
databits[i] = 0;
}
}
}
void printBits()
{
// I really hope you can figure out what this function does
Serial.print("FC = ");
Serial.print(facilityCode);
Serial.print(", CC = ");
Serial.println(cardCode);
}
So I am trying to use this code to decode the 35 bit from my card. However, when I first run the program, it starts reading random values which I am not sure where it comes from.
Also, when I try to read a card, there is nothing that outputs onto the serial monitor. Supposedly, this code worked for many users in 2013ish so what could be the issue here?