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/*
* HID RFID Reader Wiegand Interface for Arduino Uno
* Originally by Daniel Smith, 2012.01.30 -- http://www.pagemac.com/projects/rfid/arduino_wiegand
*
* Updated 2016-11-23 by Jon "ShakataGaNai" Davis.
* See https://obviate.io/?p=7470 for more details & instructions
*/
#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
int LED_GREEN = 11;
int LED_RED = 12;
int BEEP_BEEP = 10;
// 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(LED_RED, OUTPUT);
pinMode(LED_GREEN, OUTPUT);
pinMode(BEEP_BEEP, OUTPUT);
digitalWrite(LED_RED, HIGH); // High = Off
digitalWrite(BEEP_BEEP, HIGH); // High = off
digitalWrite(LED_GREEN, LOW); // Low = On
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(0, ISR_INT0, FALLING);
attachInterrupt(1, 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. ");
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() {
Serial.print("FC = ");
Serial.print(facilityCode);
Serial.print(", CC = ");
Serial.println(cardCode);
// Now lets play with some LED's for fun:
digitalWrite(LED_RED, LOW); // Red
if(cardCode == 12345){
// If this one "bad" card, turn off green
// so it's just red. Otherwise you get orange-ish
digitalWrite(LED_GREEN, HIGH);
}
delay(500);
digitalWrite(LED_RED, HIGH); // Red Off
digitalWrite(LED_GREEN, LOW); // Green back on
// Lets be annoying and beep more
digitalWrite(BEEP_BEEP, LOW);
delay(500);
digitalWrite(BEEP_BEEP, HIGH);
delay(500);
digitalWrite(BEEP_BEEP, LOW);
delay(500);
digitalWrite(BEEP_BEEP, HIGH);
}
@ShakataGaNai
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ShakataGaNai commented Sep 24, 2021

@SpeedGP

if left to run for over a few hours

I don't see a reason why it would be a problem. The code does very very little beyond exactly what is required to decode the bits. There is a small memory of stuff, but only used to keep track of the bits coming in. If it's been longer than 3 seconds since the bits came in, then that memory is reset.

In short, I can't see any reason why it would be a problem, but I never actually tested this in production.

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