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LED - Controlling LED from Webpage with Image

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  • LED - Controlling LED from Webpage with Image


    Tutorial Video



    Hardware
    • PHPoC Blue (+ USB WLAN) or PHPoC Black (+ Ethernet cable)
    • Micro USB to USB Cable (to upload source code to PHPoC Device)


    About Built-in LED

    There are some LEDs are built-in on PHPoC board. This helps user quickly get started without wiring anything. These LED were already connected to IO pin of PHPoC device.

    How to control built-in LED:
    • These LEDs are turned ON by setting IO pin of PHPoC device to LOW (0 V).
    • These LEDs are turned OFF by setting IO pin of PHPoC device to HIGH (3.3 V).


    Quick Steps

    Source code of this example is a part of PHPoC Support Packet (PSP). You need to:
    • Download PHPoC Support Package.
    • Upload example\p4s\03.html_image\01.uio_ob_led to PHPoC Blue/Black.
    • Configure network parameters (e.g. WiFi SSID, password, IP address ...).
    • Access webpage on PHPoC using Web Browser on your PC or smart phone (See How To).
    If you use PHPoC for the first time, see How To Use PSP.


    Source Code

    Source files includes:
    • index.php: this file contains source code of web page.It is only run in response to request from Web Browser.
    • button_pop.png: Image.
    • button_push.png: Image.

    index.php

    [Full Code]
    PHP Code:
    <html>
    <head>
    <title>PHPoC / <?echo system("uname -i")?></title>
    <meta name="viewport" content="width=device-width, initial-scale=0.5">
    <style> body { text-align: center; } </style>
    </head>
    <body>

    <h2>

    UIO / On-Board User LED<br>

    <br>

    <?php

    include_once "/lib/sd_340.php";

    define("OUT_PIN"30);

    uio_setup(0OUT_PIN"out");

    if((
    $led0 _GET("led0")))
    {
     if(
    $led0 == "low")
      
    uio_out(0OUT_PINLOW);
     else
      
    uio_out(0OUT_PINHIGH);
    }

    if(
    uio_in(0OUT_PIN) == LOW)
     echo 
    "<a href='index.php?led0=high'><img src='button_push.png'></a><br>\r\n";
    else
     echo 
    "<a href='index.php?led0=low'><img src='button_pop.png'></a><br>\r\n";

    ?>

    </h2>

    </body>
    </html>



    [Explanation]

    Source code of index.php file is composed of HTML, CSS and PHPoC code.

    PHPoC code is interpreted on on PHPoC device.
    • PHP Code:
      <?php

          
      include_once "/lib/sd_340.php";

          
      define("OUT_PIN"30);

          
      uio_setup(0OUT_PIN"out");

          if((
      $led0 _GET("led0")))
          {
           if(
      $led0 == "low")
            
      uio_out(0OUT_PINLOW);
           else
            
      uio_out(0OUT_PINHIGH);
          }

          if(
      uio_in(0OUT_PIN) == LOW)
           echo 
      "<a href='index.php?led0=high'><img src='button_push.png'></a><br>\r\n";
          else
           echo 
      "<a href='index.php?led0=low'><img src='button_pop.png'></a><br>\r\n";

          
      ?>
    This code does:
    • Setup IO pin to output mode.
    • Get the requested state from HTTP request.
    • Control the state of built-in LED according to the requested state.
    • Read the current state of built-in LED .
    • Print out image hyperlink, which can be used to toggle state of built-in LED to webpage.


    PHPoC code may add/update the content of HTML, CSS or JavaScript code. Once PHPoC code is interpreted in PHPoC, the remaining code is client-side code and it is returned to Web Browser. Web Browser receives this code and interpret it to display the webpage.
    • HTML: describes the structure of Web pages
    • CSS: describes how HTML elements are to be displayed
    For detail explanation, see How to Control Devices via HTTP Request




    See Also

    Other Resources
    Last edited by support; 02-09-2018, 08:59 AM.
      Posting comments is disabled.

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