Published February 16, 2017 © GPL3+

PHPoC Blue with Wiegand RFID Reader

Reading RFID tags from an RFID reader with Wiegand protocol and displaying it in a web browser through a web socket.

IntermediateShowcase (no instructions)8 hours3,239

Things used in this project

Hardware components

PHPoC Blue

with a USB WIFI dongle

Jumper wires (generic)

RFID Reader

Story

The PHPoC Blue is interfaced with a RFID card reader through the Wiegand interface. When a RFID card is tagged to the RFID card reader, it sends the card information to the PHPoC Blue through the Wiegand interface.

Wiegand Protocol

The Wiegand interface is a de-facto standard which gets RFID card data through the 2 signal wires - D0 and D1. (Refer: https://en.wikipedia.org/wiki/Wiegand_interface)

Wiegand protocol signal representation and timing

The Wiegand Protocol uses two data lines - Do and D1. The D0 represents "0" and the D1 represents "1" and both are active LOW. It is a bit stream including data pulse widths and data intervals. The data will be placed at the timing of the data pulse width and there's no data during the data intervals.

Wiegand Data Format

The bit stream is composed with 26 bit data - two parity bits and 24 data bits. The parity bits are placed in the first and last position. The first bit is an even parity of former 12 bits and the last bit is a ODD parity of the latter 12 bits.

The following is a screen of oscilloscope which displays the wiegand signals.

Components

1. PHPoC Blue with a USB WiFi dongle

2. RFID reader (it is from here)

3. DC +12V Power Supplier

4. Jump wires

5. Smart device (Smart phone or Smart pad)

Software Implementation

The PHPoC Blue's Hardware timer pins(HT0 and HT1) are connected to the RFID reader's D0 and D1 pins respectively.

It counts the duration between edges incoming from the HT0 and HT1. And it makes binary bit streams by using the duration data for each ports. It can make only "0" bit stream with the HT0 and only "1" bit stream with the HT1. But we can calculate "1" data and "0" data by using the rest period from each the HT0 and HT1 respectively.

Now we have two bit stream from the each port. We can get real data if we remove the duplicated data. The last thing we have to do is calculate the parity if there is any error in the data frame.

Demonstration

Code

<?php

define ("WIEGAND_DATA_PULSE_WIDTH", 100); // 100 us
define ("WIEGAND_DATA_INTERVAL", 1600);   // 1600 us

function check_wiegand26_parity($str)
{
    if(strlen($str) != 26) return false;
    
    // bit 0 parity : EVEN for the former 12bit (bit1 ~ bit 12)
    for($i = 1, $cnt = 0; $i < 13; $i++) if(substr($str, $i, 1) == "1") $cnt++;
    if($cnt % 2 && (substr($str, 0, 1) == "0")) return false;
    if(!($cnt % 2) && (substr($str, 0, 1) == "1")) return false;
    
    // bit 25 parity : ODD for the latter 12bit (bit13 ~ bit 24)
    for($i = 13, $cnt = 0; $i < 25; $i++) if(substr($str, $i, 1) == "1") $cnt++;
    if($cnt % 2 && (substr($str, 25, 1) == "1")) return false;
    if(!($cnt % 2) && (substr($str, 25, 1) == "0")) return false;
    
    return true;
}
 
function binstr2int($binstr)
{
    for($i = strlen($binstr) - 1, $pos = 0, $num = 0; $i >= 0; $i--, $pos++)
    {
        if(substr($binstr, $i, 1) == "1") $num |= (1 <<$pos);
    }
    return $num;
}
 
function get_wiegand26_id($str)
{
    if(strlen($str) != 26) return false;
    
    $str_id = substr($str, 9, 16);
    $id = binstr2int($str_id);
    
    return $id;
}
 
function get_wiegand26_fac_code($str)
{
    if(strlen($str) != 26) return false;
    
    $str_code = substr($str, 1, 8);
    $code = binstr2int($str_code);
    
    return $code;
}
 
function get_wiegand26_full_id($str)
{
    if(strlen($str) != 26) return false;
    
    $str_full_id = substr($str, 1, 24);
    $full_id = binstr2int($str_full_id);
    
    return $full_id;
}
 
function wiegand_scan()
{
    $ht0 = pid_open("/mmap/ht0");
    $ht1 = pid_open("/mmap/ht1");
 
/* 
    div_unit : 42(1us)
    data pulse width range: 20us - 100us
    data interval : 200us - 20ms
    Maximum data duration: 520ms (maximum bit length: 20ms * 26 bits)
*/
	$time_unit = 20; // 20us
	$div_unit  = 20 * 42; // 1us: 42
	$bit_slot  = WIEGAND_DATA_INTERVAL / 20;
 
    $frame_len = 26;
    $bad_format = "Bad Wiegand Format";
   
    pid_ioctl($ht0, "set div $div_unit");
    pid_ioctl($ht1, "set div $div_unit");
    pid_ioctl($ht0, "set mode capture fall");
    pid_ioctl($ht1, "set mode capture rise");
    pid_ioctl($ht0, "set repc $frame_len");
    pid_ioctl($ht1, "set repc $frame_len");
    pid_ioctl($ht0, "set trigger from pin fall");
    pid_ioctl($ht1, "set trigger from pin fall");
 
    pid_ioctl($ht0, "start");
    pid_ioctl($ht1, "start");

    // getting durations each edges for D0(ht0) and D1(ht1)
    while(1)
    {
        $st_ht0 = pid_ioctl($ht0, "get state");
        $st_ht1 = pid_ioctl($ht1, "get state");
    
        $ht0_cnt = $frame_len - pid_ioctl($ht0, "get repc");
        $ht1_cnt = $frame_len - pid_ioctl($ht1, "get repc");
 
        if(($ht0_cnt + $ht1_cnt) >= $frame_len) break;
        if($st_ht0 == 0 && $st_ht1 == 0) break;
    }
 
    pid_ioctl($ht0, "stop");
    pid_ioctl($ht1, "stop");

    // making binary string by duration of ht0(D0)
    //   adding "0" for each edge
    //   adding "1" supposed position between "0"s 
    $ht0_str = "0";
    for($i = 1; $i < $ht0_cnt; $i++) 
    {
        $cnt = pid_ioctl($ht0, "get count $i");
        $tmp = (int)(round($cnt/$bit_slot));
        for($j = 1; $j<$tmp; $j++) $ht0_str .= "1";
        $ht0_str .= "0";
    }

    // making binary string by duration of ht1(D1)
    //   adding "1" for each edge
    //   adding "0" supposed position between "1"s 
    $ht1_str = "1";
    for($i = 1; $i < $ht1_cnt; $i++) 
    {    
        $cnt = pid_ioctl($ht1, "get count $i");
        $tmp = (int)(round($cnt/$bit_slot));
        for($j = 1; $j<$tmp; $j++) $ht1_str .= "0";
        $ht1_str .= "1";
    }
    
 
    pid_close($ht0);
    pid_close($ht1);
 
    $strlen_ht0 = strlen($ht0_str);
    $strlen_ht1 = strlen($ht1_str);


     // for debugging
    echo "ht0_str($strlen_ht0) = $ht0_str\r\n";
    echo "ht1_str($strlen_ht1) = $ht1_str\r\n";

	// merging D0 and D1 by removing duplicated data
    $rfid = "";
    $len_intersection = $strlen_ht0 + $strlen_ht1 - $frame_len;
 
    // when either string size is equal to max string size
    if($strlen_ht0 >= $frame_len)
    {
        if(strpos($ht0_str, $ht1_str) !== false) $rfid = $ht0_str;
        else $rfid = $bad_format;
    }
    else if($strlen_ht1 >= $frame_len)
    {
        if(strpos($ht1_str, $ht0_str) !== false) $rfid = $ht1_str;
        else $rfid = $bad_format;
    }
    // when the sum of two string size is equal to max string size
    else if(($strlen_ht0 + $strlen_ht1) == $frame_len)
    {
        if(check_wiegand26_parity($ht0_str . $ht1_str) == true) $rfid = $ht0_str . $ht1_str;
        else if(check_wiegand26_parity($ht1_str . $ht0_str) == true) $rfid = $ht1_str . $ht0_str;
        else $rfid = $bad_format;
    }
    // the others
    else
    {
        $tmp_str = substr($ht0_str, 0, $len_intersection);
        $ident_pos0 = strpos($ht1_str, $tmp_str, $strlen_ht1-$len_intersection);    
 
        $tmp_str = substr($ht1_str, 0, $len_intersection);    
        $ident_pos1 = strpos($ht0_str, $tmp_str, $strlen_ht0-$len_intersection);
 
        if($ident_pos0 !== false) $rfid = $ht1_str . substr($ht0_str, $len_intersection);
        else if($ident_pos1 !== false) $rfid = $ht0_str . substr($ht1_str, $len_intersection);
        else $rfid = $bad_format;
    }
        
    return $rfid;
}
 
 
?>

<?php
 
include_once "lib/sn_tcp_ws.php";
include_once "wiegand.php";
 
ws_setup(0, "rfid", "csv.phpoc");
 
$rwbuf = "";
$count = 1;
 
$state_old = 0;
 
while(1)
{
    $rfid = wiegand_scan();
    
    if(check_wiegand26_parity($rfid) == false) 
    {
    	$full_id="error";
    	echo "wiegand: parity error($rfid)\r\n";
	}
    else
    {
        $id = get_wiegand26_id($rfid);
        $fac_code = get_wiegand26_fac_code($rfid);
        $full_id = get_wiegand26_full_id($rfid);
        echo "full_id: $full_id, fac_code: $fac_code, id: $id\r\n";
    }
    
    if(ws_state(0) == TCP_CONNECTED)
    {
        ws_write(0, "$full_id");
        echo "full_id: $full_id, fac_code: $fac_code, id: $id\r\n";
    }
}
 
?>

<?php
$ws_host = _SERVER("HTTP_HOST");
?>
<!DOCTYPE html>
<html>
<head>
<title>PHPoC</title>
<script>
var ws;
var count = 1;
function ws_init()
{
    ws = new WebSocket("ws://<?echo $ws_host?>/rfid", "csv.phpoc");
 
    //ws.onopen  = function(){ document.getElementById("ws_state").innerHTML = "connected" };
    ws.onclose = function(){ document.getElementById("ws_state").innerHTML = "closed"};
    ws.onerror = function(){ alert("websocket error " + this.url) };
 
    ws.onopen = ws_onopen;
    ws.onmessage = ws_onmessage;
}
function ws_onopen(e_msg)
{
    e_msg = e_msg || window.event; // MessageEvent
     
    document.getElementById("ws_state").innerHTML = "connected";
    document.getElementById("ws_reply").innerHTML = e_msg.data;
}
function ws_onmessage(e_msg)
{
    e_msg = e_msg || window.event; // MessageEvent
 
    document.getElementById("ws_reply").innerHTML = e_msg.data;
}
window.onload = ws_init;
</script>
</head>
 
<body>
 
<img style="margin:0px auto;display:block" src="k5-dam.jpg">
<h1 style="text-align:center" id="ws_reply">-</h1>
 
</body>
</html>

Credits

Matthew Lee

2 projects • 28 followers

Hardware Engineer

PHPoC Blue with Wiegand RFID Reader

Things used in this project

Hardware components

Story

Wiegand Protocol

Components

Software Implementation

Demonstration

Schematics

file_sbqk4twvda_76PpdgoepD.jpg

Code

wiegand.php

task0.php

index.php

Credits

Matthew Lee

Comments

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PHPoC Blue with Wiegand RFID Reader

PHPoC Blue with Wiegand RFID Reader

Things used in this project

Hardware components

Story

Wiegand Protocol

Components

Software Implementation

Demonstration

Schematics

file_sbqk4twvda_76PpdgoepD.jpg

Code

wiegand.php

task0.php

index.php

Credits

Matthew Lee

Comments

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