Tweet
- Demonstration
- System Components
- Things used in this project
- Wiring Diagram
- The Working Flow
- Source Codes
For irregular customers in parking lots, they have to pay parking fee per time rather than per month. It’s inconvenient to do payment by cash.
With RFID technology, we can build an automated payment system. In detail, amount of money is charged to a RFID tag. Each time for the parking, the customer just need to tap the tag to a device, the parking fee is subtracted from the charged money in the tag.
Demonstration
System Components
The system includes two devices:
- Money charging device (to charge money to RFID card)
- Parking fee payment device (to subtract money from card each time parking)
In the demonstration video, I combined two devices into one.
Main components of the two devices are PN532, PHPoC and MIFARE Classic Tags.
- PN532 and PHPoC keep a role in charging money to the card, subtracting the parking fee from the card for each time parking.
- MIFARE Classic Tags is to store the money.
Someone may ask a question: Is it possible for a tag to be modified on charging amount by an unauthorized person? The answer is no or too difficult to hack it because of the following reasons:
- Reading/writing from/to the tag is protected by password.
- Data is encrypted before writing to card using the crypto algorithm (in this project I use RC4 Algorithm).
- A cyclic redundancy check (CRC) is used to detect accidental changes to raw data.
Things Used In This Project
Money Charging Device
- PHPoC Blue or Black
- PN532 NFC/RFID controller (in my case, I used Adafruit PN532 RFID/NFC Breakout)
- Some MIFARE Classic Tags
- PHPoC bread board (Optional)
- Jumper wires
Parking Fee Payment Device
- PHPoC Blue or Black
- PN532 NFC/RFID controller (in my case, I used Adafruit PN532 RFID/NFC Breakout)
- Some NFC/RFID tags
- PHPoC bread board (Optional)
- Servo motor
- Jumper wires
- Lego Brick
Wiring Diagram
- PHPoC----------- Adafruit PN532
- 3V---------------3.3V (Red wire)
- SCK --------------SCK (Yellow wire)
- MISO------------MISO (Green wire)
- MOSI-----------MOSI (Blue wire)
- 4 -----------------SSEL (White wire)
- GND-------------GND (Gray wire)
- PHPoC----------- Servo Motor
- GND-------------GND
- 5v--------------- vcc
- Ht0--------------- signal pin
Working Flow
Money Charging Device
The below image shows the working flow on server side (task0.php).Other part is a web-based user interface (index.php) which is not shown here.
Parking Fee Payment Device
The two devices above use two important functions: Read and write money to RFID tag. The below diagram depicts how it works.
Source Codes
Money Charging Device
Source codes for Money Charging Device includes two part:
- Task0.php: This script runs in infinite loop and responsible for checking command and amount of charging money from websocket, and charging money to RFID tag.
- Index.php: This script provides the user interface, send command and amount of charging money via websocket.
<task0.php>
PHP Code:
<?php
if(_SERVER("REQUEST_METHOD"))
exit; // avoid php execution via http request
include_once "/lib/sd_340.php";
include_once "/lib/sn_tcp_ws.php";
include_once "vd_pcd_pn532.php";
include_once "vd_mifare_classic.php";
define("DEFAULT_KEY", "\xFF\xFF\xFF\xFF\xFF\xFF"); // Default Tag Key
define("STATUS_CODE_MONEY_AMOUNT", '0');
define("STATUS_CODE_READ_ERROR", '1');
define("STATUS_CODE_TAG_STATUS", '2');
define("STATUS_CODE_CHARGE_STATUS", '3');
/*Tag Key to read/write data from/to Tag*/
$tag_key = "\xEF\xFF\xFF\xFF\xFF\xFF"; //Change your desired tag key here. It must be 6 bytes in length
/*RC4 Key to encript data before writing to the tag and decript data after reading from the tag*/
$rc4_key = "\x01\x03\x05\x06\x1A\AA"; //Change your desired key here
function read_money_from_tag($uid)
{
global $tag_key, $rc4_key;
$block_addr = 1;
$rbuf = "";
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if($ret_val)
{
$ret_val = mifare_classic_read_data_block($block_addr, $rbuf);
if(!$ret_val)
return false;
$length = bin2int($rbuf, 0, 2); // Two first bytes of block 1 is length value.
$data_len = $length - 2; // Two byte CRC
if(!$length)
return 0;
$data_buf = substr($rbuf, 2);
$block_addr++;
while($length > 0) //each block is 16 byte
{
if(vn_mifare_classic_is_trailer_block($block_addr) )
$block_addr++; //Ignore trailer block;
if(vn_mifare_classic_is_first_block($block_addr))
{
//When moving to new sector we need to do authenticaiton again.
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if(!$ret_val)
return false;
}
$ret_val = mifare_classic_read_data_block($block_addr, $rbuf);
if(!$ret_val)
return false;
$data_buf .= $rbuf;
$length -= 16;
$block_addr++;
}
$data = substr($data_buf, 0, $data_len);
$crc = substr($data_buf, $data_len, 2);
//check CRC
$crc_data = (int)system("crc 16 %1", $data);
$crc_data = int2bin($crc_data,2);
if($crc != $crc_data)
return false;
// decryption
$rc4 = system("rc4 init %1", $rc4_key); // initialize
$money = system("rc4 crypt %1 %2", $rc4, $data); // decryption
return (int)$money;
}
else
{
echo "Authentication Error\r\n";
return false;
}
}
function write_money_to_tag($uid, $money)
{
global $tag_key, $rc4_key;
//format int to string.
$money = sprintf("%d", $money);
// encryption
$rc4 = system("rc4 init %1", $rc4_key); // initialize
$data = system("rc4 crypt %1 %2", $rc4, $money); // encryption
//Calculate CRC
$crc = (int)system("crc 16 %1", $data);
$data .= int2bin($crc, 2);
$length = strlen($data);
//Append two byte data length
$data = int2bin($length, 2) .$data;
$length += 2;
$block_addr = 1;
$pointer = 0;
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if(!$ret_val)
return false;
while($pointer < $length) //each block is 16 byte
{
if(vn_mifare_classic_is_trailer_block($block_addr) )
$block_addr++; //Ignore trailer block;
if(vn_mifare_classic_is_first_block($block_addr))
{
//When moving to new sector we need to do authenticaiton again.
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if(!$ret_val)
return false;
}
$wbuf = substr($data, $pointer, 16);
if(strlen($wbuf) < 16)
$wbuf .= str_repeat("\x00", (16 - strlen($wbuf)));
$ret_val = mifare_classic_write_data_block($block_addr, $wbuf);
if(!$ret_val)
return false;
$pointer += 16;
$block_addr++;
}
return true;
}
function check_new_tag($uid)
{
global $tag_key;
//check whether tag is new.
for($sector_addr = 0; $sector_addr < 15; $sector_addr++)
{
$ret_val = mifare_classic_authenticate_sector($uid, $sector_addr, DEFAULT_KEY, "A");
if($ret_val)
{
//Change key
$ret_val = mifare_classic_change_key($sector_addr, $tag_key, "A");
if(!$ret_val)
echo "Mifare: sector $sector_addr changed key unsuccessfully\r\n";
}
else
{
break;
}
}
reader_ISO14443A_is_present($uid);
}
reader_init();
ws_setup(0, "WebConsole", "text.phpoc");
$uid = "";
$rbuf = "";
$pre_uid = "";
while(1)
{
if(ws_state(0) != TCP_CONNECTED) // charging mode
continue;
if(!reader_ISO14443A_is_present($uid))
{
$wbuf = '{"code": '. STATUS_CODE_TAG_STATUS .', "data":"Unavailable"}';
ws_write(0, $wbuf);
// delete receiving buffer if existed
$rlen = ws_read(0, $rbuf);
usleep(500000);
continue;
}
if($pre_uid != $uid)
{
check_new_tag($uid);
//Recheck tag key
$ret_val = mifare_classic_authenticate_block($uid, 1, $tag_key, "A");
if($ret_val)
{
echo "System works with tag key\r\n";
}
else
exit("System does not work with tag key\r\n");
$pre_uid = $uid;
}
$current_money = read_money_from_tag($uid);
if($current_money !== false)
$wbuf = '{"code": '. STATUS_CODE_MONEY_AMOUNT .', "data":' . "$current_money" . '}';
else
$wbuf = '{"code": '. STATUS_CODE_READ_ERROR .', "data":"Read error!"}';
ws_write(0, $wbuf);
//Check command from app.
$rlen = ws_read_line(0, $rbuf);
if($rlen)
{
$data_array = explode(" ", $rbuf);
$cmd = (int)$data_array[0];
$money = (int)$data_array[1];
$new_money = $current_money + $money;
if(write_money_to_tag($uid, $new_money))
{
$wbuf = '{"code": '. STATUS_CODE_CHARGE_STATUS .', "data":"Successful"}';
}
else
{
$wbuf = '{"code": '. STATUS_CODE_CHARGE_STATUS .', "data":"Fail"}';
}
ws_write(0, $wbuf);
}
}
?>
<index.php>
PHP Code:
<?php
define("STATUS_CODE_MONEY_AMOUNT", '0');
define("STATUS_CODE_READ_ERROR", '1');
define("STATUS_CODE_TAG_STATUS", '2');
define("STATUS_CODE_CHARGE_STATUS", '3');
?>
<html>
<head>
<title>PHPoC / NFC-RFID Reader</title>
<meta name="viewport" content="width=device-width, initial-scale=0.7">
<style>
td {color:gray;}
table{
margin-right: auto;
margin-left: auto;
padding-bottom: 50px;
padding-top: 50px;
width: 1000px;
background: url(background.png) no-repeat;
background-size: contain;
position: relative;
border: 1px solid #000;
}
td, span, input, button{
font-weight: bold;
font-family:courier;
font-size:40px;
padding: 5px
}
span, input {color:orange;}
.field {
width: 400px;
text-align: right;
}
table tr.separator { height: 10px; }
</style>
<script>
var ws;
var wc_max_len = 32768;
var cmd = 1;
function init()
{
show_block("div_charge");
}
function ws_onopen()
{
document.getElementById("ws_state").innerHTML = "OPEN";
document.getElementById("wc_conn").innerHTML = "Disconnect";
document.getElementById("charge_status").innerHTML = "None";
}
function ws_onclose()
{
document.getElementById("ws_state").innerHTML = "CLOSED";
document.getElementById("wc_conn").innerHTML = "Connect";
ws.onopen = null;
ws.onclose = null;
ws.onmessage = null;
ws = null;
show_block("div_charge");
document.getElementById("tag_status").innerHTML = "Unavailable";
document.getElementById("current_amount").innerHTML = "";
document.getElementById("btn_charge").disabled = true;
}
function wc_onclick()
{
if(ws == null)
{
ws = new WebSocket("ws://<?echo _SERVER("HTTP_HOST")?>/WebConsole", "text.phpoc");
document.getElementById("ws_state").innerHTML = "CONNECTING";
ws.onopen = ws_onopen;
ws.onclose = ws_onclose;
ws.onmessage = ws_onmessage;
}
else
ws.close();
}
function ws_onmessage(e_msg)
{
var obj = JSON.parse(e_msg.data);
console.log(e_msg.data);
switch(obj.code)
{
case <?php echo STATUS_CODE_MONEY_AMOUNT?>:
document.getElementById("current_amount").innerHTML = obj.data;
document.getElementById("tag_status").innerHTML = "Available";
document.getElementById("btn_charge").disabled = false;
break;
case <?php echo STATUS_CODE_READ_ERROR?>:
document.getElementById("current_amount").innerHTML = obj.data;
document.getElementById("tag_status").innerHTML = "Available";
document.getElementById("btn_charge").disabled = true;
break;
case <?php echo STATUS_CODE_TAG_STATUS?>:
document.getElementById("tag_status").innerHTML = obj.data;
document.getElementById("current_amount").innerHTML = "";
document.getElementById("btn_charge").disabled = true;
break;
case <?php echo STATUS_CODE_CHARGE_STATUS?>:
document.getElementById("charge_status").innerHTML = obj.data;
show_block("div_charge");
break;
}
}
function show_chargeIU()
{
document.getElementById("btn_send").disabled = false;
document.getElementById("charge_status").innerHTML = "None";
show_block("div_input");
}
function send_data()
{
document.getElementById("btn_send").disabled = true;
var data = document.getElementById("charge_amount").value;
send_command(cmd, data);
}
function send_command(cmd, data)
{
if(ws != null)
if(ws.readyState == 1)
ws.send(cmd + " " + data + "\r\n");
console.log("cmd:"+cmd);
}
function show_block(className)
{
var array = document.getElementsByClassName(className);
for (i = 0; i < array.length; i++)
{
array[i].style.display = "block";
}
className = (className == "div_input") ? "div_charge" : "div_input";
array = document.getElementsByClassName(className);
for (i = 0; i < array.length; i++)
{
array[i].style.display = "none";
}
}
window.onload = init;
</script>
</head>
<body>
<h2>
<center>
<button id="wc_conn" type="button" onclick="wc_onclick();" style=" margin: 15px;">Connect</button>
</center>
<table>
<tr>
<td class="field">Web Socket:</td>
<td><span id="ws_state">CLOSED</span></td>
</tr>
<tr class="separator"><td></td><td></td></tr>
<tr>
<td class="field">Tag Status:</td>
<td><span id="tag_status">Unavailable</span></td>
</tr>
<tr>
<td class="field">Current Amount:</td>
<td><span id="current_amount"></span> KRW</td>
</tr>
<tr class="separator"><td></td><td></td></tr>
<tr>
<td class="field">
<div class="div_input" style="display:none">Charge Amount:</div>
<div class="div_charge" style="display:block">Charge Status:</div>
</td>
<td>
<div class="div_input" style="display:none">
<input type="number" id="charge_amount" value=0 style="width:200px">
KRW
<button type="button" id="btn_send" onclick="send_data();">Send</button>
</div>
<div class="div_charge" style="display:block">
<span id="charge_status">None </span>
<button type="button" id="btn_charge" onclick="show_chargeIU();" disabled>Charge</button>
</div>
</td>
</tr>
<tr>
<td class="field"></td>
<td>
</td>
</tr>
</table>
</h2>
</body>
</html>
Parking Fee Payment Device
This device doesn’t require interface. Therefore, it just includes only one part: task0.php.
<task0.php>
PHP Code:
<?php
if(_SERVER("REQUEST_METHOD"))
exit; // avoid php execution via http request
include_once "/lib/sd_340.php";
include_once "vd_pcd_pn532.php";
include_once "vd_mifare_classic.php";
define("PWM_PERIOD", 20000); // 20000us (20ms)
define("WIDTH_MIN", 600);
define("WIDTH_MAX", 2450);
define("DEFAULT_KEY", "\xFF\xFF\xFF\xFF\xFF\xFF"); // Default Tag Key
define("STATUS_CODE_MONEY_AMOUNT", '0');
define("STATUS_CODE_READ_ERROR", '1');
define("STATUS_CODE_TAG_STATUS", '2');
define("STATUS_CODE_CHARGE_STATUS", '3');
define("PARKING_FEE", 2000); //unit: KRW
/*Tag Key to read/write data from/to Tag*/
$tag_key = "\xEF\xFF\xFF\xFF\xFF\xFF"; //Change your desired tag key here. It must be 6 bytes in length
/*RC4 Key to encript data before writing to the tag and decript data after reading from the tag*/
$rc4_key = "\x01\x03\x05\x06\x1A\AA"; //Change your desired key here
function read_money_from_tag($uid)
{
global $tag_key, $rc4_key;
$block_addr = 1;
$rbuf = "";
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if($ret_val)
{
$ret_val = mifare_classic_read_data_block($block_addr, $rbuf);
if(!$ret_val)
return false;
$length = bin2int($rbuf, 0, 2); // Two first bytes of block 1 is length value.
$data_len = $length - 2; // Two byte CRC
if(!$length)
return 0;
$data_buf = substr($rbuf, 2);
$block_addr++;
while($length > 0) //each block is 16 byte
{
if(vn_mifare_classic_is_trailer_block($block_addr) )
$block_addr++; //Ignore trailer block;
if(vn_mifare_classic_is_first_block($block_addr))
{
//When moving to new sector we need to do authenticaiton again.
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if(!$ret_val)
return false;
}
$ret_val = mifare_classic_read_data_block($block_addr, $rbuf);
if(!$ret_val)
return false;
$data_buf .= $rbuf;
$length -= 16;
$block_addr++;
}
$data = substr($data_buf, 0, $data_len);
$crc = substr($data_buf, $data_len, 2);
//check CRC
$crc_data = (int)system("crc 16 %1", $data);
$crc_data = int2bin($crc_data,2);
if($crc != $crc_data)
return false;
// decryption
$rc4 = system("rc4 init %1", $rc4_key); // initialize
$money = system("rc4 crypt %1 %2", $rc4, $data); // decryption
return (int)$money;
}
else
{
echo "Authentication Error\r\n";
return false;
}
}
function write_money_to_tag($uid, $money)
{
global $tag_key, $rc4_key;
//format int to string.
$money = sprintf("%d", $money);
// encryption
$rc4 = system("rc4 init %1", $rc4_key); // initialize
$data = system("rc4 crypt %1 %2", $rc4, $money); // encryption
//Calculate CRC
$crc = (int)system("crc 16 %1", $data);
$data .= int2bin($crc, 2);
$length = strlen($data);
//Append two byte data length
$data = int2bin($length, 2) .$data;
$length += 2;
$block_addr = 1;
$pointer = 0;
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if(!$ret_val)
return false;
while($pointer < $length) //each block is 16 byte
{
if(vn_mifare_classic_is_trailer_block($block_addr) )
$block_addr++; //Ignore trailer block;
if(vn_mifare_classic_is_first_block($block_addr))
{
//When moving to new sector we need to do authenticaiton again.
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if(!$ret_val)
return false;
}
$wbuf = substr($data, $pointer, 16);
if(strlen($wbuf) < 16)
$wbuf .= str_repeat("\x00", (16 - strlen($wbuf)));
$ret_val = mifare_classic_write_data_block($block_addr, $wbuf);
if(!$ret_val)
return false;
$pointer += 16;
$block_addr++;
}
return true;
}
function check_new_tag($uid)
{
global $tag_key;
//check whether tag is new.
for($sector_addr = 0; $sector_addr < 15; $sector_addr++)
{
$ret_val = mifare_classic_authenticate_sector($uid, $sector_addr, DEFAULT_KEY, "A");
if($ret_val)
{
//Change key
$ret_val = mifare_classic_change_key($sector_addr, $tag_key, "A");
if(!$ret_val)
echo "Mifare: sector $sector_addr changed key unsuccessfully\r\n";
}
else
{
break;
}
}
reader_ISO14443A_is_present($uid);
}
function servo_set_angle($angle)
{
$width = WIDTH_MIN + (int)round((WIDTH_MAX - WIDTH_MIN) * $angle / 180.0);
if(($width >= WIDTH_MIN) && ($width <= WIDTH_MAX))
ht_pwm_width(0, $width, PWM_PERIOD);
}
ht_pwm_setup(0, WIDTH_MIN, PWM_PERIOD, "us");
servo_set_angle(45);
reader_init();
$uid = "";
$rbuf = "";
$pre_uid = "";
while(1)
{
if(!reader_ISO14443A_is_present($uid))
{
usleep(500000);
continue;
}
if($pre_uid != $uid)
{
check_new_tag($uid);
//Recheck tag key
$ret_val = mifare_classic_authenticate_block($uid, 1, $tag_key, "A");
if($ret_val)
{
echo "System works with tag key\r\n";
}
else
echo("System does not work with tag key\r\n");
$pre_uid = $uid;
}
$current_money = read_money_from_tag($uid);
if($current_money !== false)
{
if($current_money >= PARKING_FEE)
{
$new_money = $current_money - PARKING_FEE;
if(write_money_to_tag($uid, $new_money))
{
// TODO: open barrier
servo_set_angle(135);
sleep(5);
// close barrier
servo_set_angle(45);
}
else
{
//TODO: Alert: system error.
}
}
else
{
//TODO: Alert: Not enough Money.
}
}
else
{
//TODO: Alert: system error.
}
}
?>
Combining Two Devices into One
We just need to combine the server side (task0.php). User Interface is kept as Money Charging Device. When websocket is connected, the devices acts Money Charging Device, otherwise the devices acts as Parking Fee Payment Device.
<task0.php>
PHP Code:
<?php
if(_SERVER("REQUEST_METHOD"))
exit; // avoid php execution via http request
include_once "/lib/sd_340.php";
include_once "/lib/sn_tcp_ws.php";
include_once "vd_pcd_pn532.php";
include_once "vd_mifare_classic.php";
define("PWM_PERIOD", 20000); // 20000us (20ms)
define("WIDTH_MIN", 600);
define("WIDTH_MAX", 2450);
define("DEFAULT_KEY", "\xFF\xFF\xFF\xFF\xFF\xFF"); // Default Tag Key
define("MODE_NORMAL", 0);
define("MODE_CHARGE", 1);
define("STATUS_CODE_MONEY_AMOUNT", '0');
define("STATUS_CODE_READ_ERROR", '1');
define("STATUS_CODE_TAG_STATUS", '2');
define("STATUS_CODE_CHARGE_STATUS", '3');
define("PARKING_FEE", 2000); //unit: KRW
/*Tag Key to read/write data from/to Tag*/
$tag_key = "\xEF\xFF\xFF\xFF\xFF\xFF"; //Change your desired tag key here. It must be 6 bytes in length
/*RC4 Key to encript data before writing to the tag and decript data after reading from the tag*/
$rc4_key = "\x01\x03\x05\x06\x1A\AA"; //Change your desired key here
function read_money_from_tag($uid)
{
global $tag_key, $rc4_key;
$block_addr = 1;
$rbuf = "";
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if($ret_val)
{
$ret_val = mifare_classic_read_data_block($block_addr, $rbuf);
if(!$ret_val)
return false;
$length = bin2int($rbuf, 0, 2); // Two first bytes of block 1 is length value.
$data_len = $length - 2; // Two byte CRC
if(!$length)
return 0;
$data_buf = substr($rbuf, 2);
$block_addr++;
while($length > 0) //each block is 16 byte
{
if(vn_mifare_classic_is_trailer_block($block_addr) )
$block_addr++; //Ignore trailer block;
if(vn_mifare_classic_is_first_block($block_addr))
{
//When moving to new sector we need to do authenticaiton again.
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if(!$ret_val)
return false;
}
$ret_val = mifare_classic_read_data_block($block_addr, $rbuf);
if(!$ret_val)
return false;
$data_buf .= $rbuf;
$length -= 16;
$block_addr++;
}
$data = substr($data_buf, 0, $data_len);
$crc = substr($data_buf, $data_len, 2);
//check CRC
$crc_data = (int)system("crc 16 %1", $data);
$crc_data = int2bin($crc_data,2);
if($crc != $crc_data)
return false;
// decryption
$rc4 = system("rc4 init %1", $rc4_key); // initialize
$money = system("rc4 crypt %1 %2", $rc4, $data); // decryption
return (int)$money;
}
else
{
echo "Authentication Error\r\n";
return false;
}
}
function write_money_to_tag($uid, $money)
{
global $tag_key, $rc4_key;
//format int to string.
$money = sprintf("%d", $money);
// encryption
$rc4 = system("rc4 init %1", $rc4_key); // initialize
$data = system("rc4 crypt %1 %2", $rc4, $money); // encryption
//Calculate CRC
$crc = (int)system("crc 16 %1", $data);
$data .= int2bin($crc, 2);
$length = strlen($data);
//Append two byte data length
$data = int2bin($length, 2) .$data;
$length += 2;
$block_addr = 1;
$pointer = 0;
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if(!$ret_val)
return false;
while($pointer < $length) //each block is 16 byte
{
if(vn_mifare_classic_is_trailer_block($block_addr) )
$block_addr++; //Ignore trailer block;
if(vn_mifare_classic_is_first_block($block_addr))
{
//When moving to new sector we need to do authenticaiton again.
$ret_val = mifare_classic_authenticate_block($uid, $block_addr, $tag_key, "A");
if(!$ret_val)
return false;
}
$wbuf = substr($data, $pointer, 16);
if(strlen($wbuf) < 16)
$wbuf .= str_repeat("\x00", (16 - strlen($wbuf)));
$ret_val = mifare_classic_write_data_block($block_addr, $wbuf);
if(!$ret_val)
return false;
$pointer += 16;
$block_addr++;
}
return true;
}
function check_new_tag($uid)
{
global $tag_key;
//check whether tag is new.
for($sector_addr = 0; $sector_addr < 15; $sector_addr++)
{
$ret_val = mifare_classic_authenticate_sector($uid, $sector_addr, DEFAULT_KEY, "A");
if($ret_val)
{
//Change key
$ret_val = mifare_classic_change_key($sector_addr, $tag_key, "A");
if(!$ret_val)
echo "Mifare: sector $sector_addr changed key unsuccessfully\r\n";
}
else
{
break;
}
}
reader_ISO14443A_is_present($uid);
}
function servo_set_angle($angle)
{
$width = WIDTH_MIN + (int)round((WIDTH_MAX - WIDTH_MIN) * $angle / 180.0);
if(($width >= WIDTH_MIN) && ($width <= WIDTH_MAX))
ht_pwm_width(0, $width, PWM_PERIOD);
}
ht_pwm_setup(0, WIDTH_MIN, PWM_PERIOD, "us");
servo_set_angle(45);
reader_init();
ws_setup(0, "WebConsole", "text.phpoc");
$uid = "";
$rbuf = "";
$mode = MODE_NORMAL;
$pre_uid = "";
while(1)
{
if(ws_state(0) == TCP_CONNECTED) // charging mode
$mode = MODE_CHARGE;
else
$mode = MODE_NORMAL;
if(!reader_ISO14443A_is_present($uid))
{
if($mode == MODE_CHARGE)
{
$wbuf = '{"code": '. STATUS_CODE_TAG_STATUS .', "data":"Unavailable"}';
ws_write(0, $wbuf);
// delete receiving buffer if existed
$rlen = ws_read(0, $rbuf);
}
usleep(500000);
continue;
}
if($pre_uid != $uid)
{
check_new_tag($uid);
//Recheck tag key
$ret_val = mifare_classic_authenticate_block($uid, 1, $tag_key, "A");
if($ret_val)
{
echo "System works with tag key\r\n";
}
else
echo("System does not work with tag key\r\n");
$pre_uid = $uid;
}
$current_money = read_money_from_tag($uid);
switch($mode)
{
case MODE_NORMAL:
if($current_money !== false)
{
if($current_money >= PARKING_FEE)
{
$new_money = $current_money - PARKING_FEE;
if(write_money_to_tag($uid, $new_money))
{
// TODO: open barrier
servo_set_angle(135);
sleep(5);
// close barrier
servo_set_angle(45);
}
else
{
//TODO: Alert: system error.
}
}
else
{
//TODO: Alert: Not enough Money.
}
}
else
{
//TODO: Alert: system error.
}
break;
case MODE_CHARGE:
if($current_money !== false)
$wbuf = '{"code": '. STATUS_CODE_MONEY_AMOUNT .', "data":' . "$current_money" . '}';
else
$wbuf = '{"code": '. STATUS_CODE_READ_ERROR .', "data":"Read error!"}';
ws_write(0, $wbuf);
//Check command from app.
$rlen = ws_read_line(0, $rbuf);
if($rlen)
{
$data_array = explode(" ", $rbuf);
$cmd = (int)$data_array[0];
$money = (int)$data_array[1];
$new_money = $current_money + $money;
if(write_money_to_tag($uid, $new_money))
{
$wbuf = '{"code": '. STATUS_CODE_CHARGE_STATUS .', "data":"Successful"}';
}
else
{
$wbuf = '{"code": '. STATUS_CODE_CHARGE_STATUS .', "data":"Fail"}';
}
ws_write(0, $wbuf);
}
break;
}
}
?>
You can get the full source code here: payment_system.zip
If you have any questions or something to discuss, don’t hesitate to leave a comment. I am glad to discuss with you.