Overview
Things
Story

Brief Introduction
Wiring
How It Works

Published June 20, 2019 © GPL3+

PHPoC - Control LCD From Web

A more interesting way to control a 16x2 LCD.

BeginnerFull instructions provided1 hour697

Things used in this project

Hardware components

PHPoC Blue

DIYables LCD I2C 16x2 Display

DIYables Jumper Wires

DIYables Starter Kit

Story

Demontration

Brief Introduction

Another day, another way to control your 16x2 LCD!

This is a simple project that shows how to control LCD16x2 via I2C interface, using PHPoC. It provides a web-based controller for LCD: just input any sentence, and it will be displayed on LCD.

Wiring

Connect pin GND, VCC, and SDA and SCL of LCD16x2 to GND, PWR5V, SDA and SCL of PHPoC, respectively.

Wiring

How It Works

Well, it is pretty simple.

PHPoC Blue communicates with the LCD 16x2 via I2C interface.PHPoC and Web browser exchange data via WebSocket connection, in which, of course, PHPoC board acts as a WebSocket server.

After receiving input data from Web browser, PHPoC controls LCD to display those textual data. That's all!

<?php 

if(_SERVER("REQUEST_METHOD"))
   exit; // avoid php execution via http request


include_once "/lib/sn_tcp_ws.php";
include_once "lcd1602_i2c.php";

ws_setup(0, "lcd", "text.phpoc");
i2c_setup(0, LCD_ADDRESS); 
$rbuf ="";

begin();
back_light();
set_cursor(1,0);
lcd_print("PHPoC with LCD");

while (ws_state(0) != TCP_CONNECTED)
{   
   sleep(1);
   scroll_display_left();
   sleep(1);
   scroll_display_right();
   sleep(1);
   scroll_display_right();
   sleep(1);
   scroll_display_left();

}

while(1)
{
   if(ws_state(0) == TCP_CONNECTED)
   {
      $rlen = ws_read(0, $rbuf);

          if($rlen)
        {         
         clear();
         home();   

         for ($i=0;$i<$rlen;$i++)
         {
            lcd_print($rbuf[$i]);
            if ($i==15)
            {
               set_cursor(0,1);
            }
         }                                       
      }                                    
   }


}

?>

<!DOCTYPE html>
<html>
<head>
<title>PHPoC - LCD 1602</title>
<meta name="viewport" content="width=device-width, initial-scale=0.7, maximum-scale=0.7">
<style>
body { text-align: center; font-size: 15pt; font-family: Arial, Helvetica, sans-serif;}
h1 { font-weight: bold; font-size: 25pt; }
h2 { font-weight: bold; font-size: 15pt; }
button { font-weight: bold; font-size: 15pt; }
textarea { width:500px; height:100px; padding:20px; font-family:courier; font-size:50px; background-color: #ccff66;overflow:hidden;word-wrap:break-word;}

</style>
<script>

var ws = null;
var last_sent = null;
var timer = null;

function init()
{
   var lcd_display = document.getElementById("wc_text");
   lcd_display.addEventListener("keydown", key_down);
}


function connect_onclick()
{
   if(ws == null)
   {
      var ws_host_addr = "<?echo _SERVER("HTTP_HOST")?>";
      ws = new WebSocket("ws://" + ws_host_addr + "/lcd", "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_onopen()
{
   document.getElementById("ws_state").innerHTML = "<font color='blue'>CONNECTED</font>";
   document.getElementById("bt_connect").innerHTML = "DISCONNECT";

}


function key_down()
{
   clearTimeout(timer); 
    timer = setTimeout(send_to_lcd, 2000);
}


function ws_onclose()
{
   document.getElementById("ws_state").innerHTML = "<font color='gray'>NOT CONNECTED</font>";
   document.getElementById("bt_connect").innerHTML = "START";
   ws.onopen = null;
   ws.onclose = null;
   ws.onmessage = null;
   ws = null;

}


function ws_onmessage(e_msg)
{
   e_msg = e_msg || window.event;    
   alert("msg : " + e_msg.data);
}


function send_to_lcd()
{
   var val = document.getElementById("wc_text").value;

   if(ws != null)
   {
      if (val != last_sent)
      {
         last_sent = val;         
         ws.send(val);
      }
   }
}

window.onload = init;
</script>
</head>

<body>
<center>
<p>
<h1>PHPoC - LCD 1602</h1>
</p>

<h2>

<p>
<textarea id="wc_text" class="input" type="text" cols="20" rows="2" maxlength="32" font="Courier" ></textarea><br>
</p>

<p>
WebSocket : <span id="ws_state">null</span>
</p>

<button id="bt_connect" type="button" onclick="connect_onclick();">START</button>
</h2>
</center>
</body>
</html>

<?php
include_once "/lib/sd_340.php";

// Device I2C Adrress
define ("LCD_ADDRESS",      0x3F);

// LCD commands
define ("LCD_CLEARDISPLAY",      0x01);
define ("LCD_RETURNHOME",      0x02);
define ("LCD_ENTRYMODESET",    0x04);
define ("LCD_DISPLAY_CONTROL",   0x08);
define ("LCD_CURSORSHIFT",      0x10);
define ("LCD_FUNCTIONSET",      0x20);
define ("LCD_SETCGRAMADDR",      0x40);
define ("LCD_SETDDRAMADDR",      0x80);

// Flags for display entry mode
define ("LCD_ENTRYRIGHT",         0x00);
define ("LCD_ENTRYLEFT",         0x02);
define ("LCD_ENTRYSHIFTINCREMENT",   0x01);
define ("LCD_ENTRYSHIFTDECREMENT",    0x00);

// Flags for display on/off control
define ("LCD_DISPLAYON",      0x04);
define ("LCD_DISPLAYOFF",      0x00);
define ("LCD_CURSORON",         0x02);
define ("LCD_CURSOROFF",      0x00);
define ("LCD_BLINKON",         0x01);
define ("LCD_BLINKOFF",         0x00);

// Flags for display/cursor shift
define ("LCD_DISPLAYMOVE",   0x08);
define ("LCD_CURSORMOVE",   0x00);
define ("LCD_MOVERIGHT",   0x04);
define ("LCD_MOVELEFT",      0x00);

// Flags for function set
define ("LCD_8BITMODE",      0x10);
define ("LCD_4BITMODE",      0x00);
define ("LCD_2LINE",      0x08);
define ("LCD_1LINE",      0x00);
define ("LCD_5x10DOTS",      0x04);
define ("LCD_5x8DOTS",      0x00);
define ("LCD_BACKLIGHT",    0x08);
define ("LCD_NOBACKLIGHT",    0x00);

// Bit control
define ("EN",    0x04); //Enable bit
define ("RS",   0x01); //Register select

$display_control = 0;
$display_function = 0;
$backlight_val = 0;
$display_mode = 0;

function expander_write($data)
{
   global $backlight_val;
   i2c_write(0, ($data | $backlight_val) , 1);      
}

function pulse_enable($data)
{
   expander_write($data | EN);
   usleep(1);
   expander_write($data & (~EN));
   usleep(50);
}

function write_nibble($data)
{
   expander_write($data);
   pulse_enable($data);   
}

function send_data($value, $mode)
{
   $high_nib= $value&0xf0;
   $low_nib=($value<<4)&0xf0;
    write_nibble(($high_nib)|$mode);
   write_nibble(($low_nib)|$mode);    
}

function command($cmd)
{
   send_data($cmd, 0);
}

function display() 
{
   global $display_control;
    $display_control |= LCD_DISPLAYON;
    command(LCD_DISPLAY_CONTROL | $display_control);
}

function clear()
{
    command(LCD_CLEARDISPLAY);           
    usleep(2000);                      
}

function home()
{
    command(LCD_RETURNHOME);        
    usleep(2000);                   
}

function back_light() {
   global $backlight_val;
   $backlight_val = LCD_BACKLIGHT;
   expander_write(0);
}

function no_back_light() {
   global $backlight_val;
   $backlight_val = LCD_NOBACKLIGHT;
   expander_write(0);
}

function print_ascii($data)
{
   send_data($data, RS);      
}

function lcd_print($str) {
   $len = strlen($str);
   for ($i=0; $i < $len; $i++)
   {
      $cur_char = bin2int($str, $i, 1);
      print_ascii($cur_char);
   }
}

function scroll_display_left() {
   command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT);
}

function scroll_display_right() {
   command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT);
}

function set_cursor($col, $row){
   $row_offsets = array(0x00, 0x40);
   if (($row==0)||($row==1))
   {
      command(LCD_SETDDRAMADDR | ($col + $row_offsets[$row]));
   }
   else
   {
      echo "Please select row value again";
      return;
   }   
}

function begin()
{
   global $display_control, $backlight_val, $display_mode;

   $display_function = LCD_4BITMODE | LCD_2LINE | LCD_5x8DOTS;   

   // Wait for more than 40ms after Vcc rises to 2.7V
   usleep(50000); 

   // Turn backlight off
   $backlight_val = LCD_NOBACKLIGHT;
   expander_write($backlight_val);
   usleep(1000);

    write_nibble(0x03 << 4);
   // Wait for more than 4.1ms
    usleep(4500); 

   write_nibble(0x03 << 4);
   // Wait for more than 4.1ms
   usleep(4500);

   write_nibble(0x03 << 4); 
   // Wait for more than 100us
   usleep(150);

      // Set to 4-bit interface
   write_nibble(0x02 << 4); 

   // Set number of lines, font size
   command(LCD_FUNCTIONSET | $display_function);  

   // Turn the display on with no cursor or blinking default
   $display_control = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;
   display();

   // Clear LCD
   clear();

   // Initialize to default text direction 
   $display_mode = LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT;

   // Set the entry mode
   command(LCD_ENTRYMODESET | $display_mode);

   home();

}

?>

PHPoC - Control LCD From Web

Things used in this project

Hardware components

Story

Brief Introduction

Wiring

How It Works

Code

task0.php

index.php

lcd1602_i2c.php

Credits

Homer

Comments

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PHPoC - Control LCD From Web

PHPoC - Control LCD From Web

Things used in this project

Hardware components

Story

Brief Introduction

Wiring

How It Works

Code

task0.php

index.php

lcd1602_i2c.php

Credits

Homer

Comments

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