TextLCD.cpp

00001 /* mbed TextLCD Library, for a 4-bit LCD based on HD44780
00002  * Copyright (c) 2007-2010, sford, http://mbed.org
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy
00005  * of this software and associated documentation files (the "Software"), to deal
00006  * in the Software without restriction, including without limitation the rights
00007  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008  * copies of the Software, and to permit persons to whom the Software is
00009  * furnished to do so, subject to the following conditions:
00010  *
00011  * The above copyright notice and this permission notice shall be included in
00012  * all copies or substantial portions of the Software.
00013  *
00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00017  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00020  * THE SOFTWARE.
00021  */
00022 
00023 #include "TextLCD.h"
00024 #include "mbed.h"
00025 
00026 TextLCD::TextLCD(PinName rs, PinName e, PinName d4, PinName d5,
00027                  PinName d6, PinName d7, LCDType type) : _rs(rs),
00028         _e(e), _d(d4, d5, d6, d7),
00029         _type(type) {
00030 
00031     _e  = 1;
00032     _rs = 0;            // command mode
00033 
00034     wait(0.015);        // Wait 15ms to ensure powered up
00035 
00036     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
00037     for (int i=0; i<3; i++) {
00038         writeByte(0x3);
00039         wait(0.00164);  // this command takes 1.64ms, so wait for it
00040     //Thread::wait(2);
00041     }
00042     writeByte(0x2);     // 4-bit mode
00043 wait(0.000040f);    // most instructions take 40us
00044 //Thread::wait(1);
00045     writeCommand(0x28); // Function set 001 BW N F - -
00046     writeCommand(0x0C);
00047     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00048     cls();
00049 }
00050 
00051 void TextLCD::character(int column, int row, int c) {
00052     int a = address(column, row);
00053     writeCommand(a);
00054     writeData(c);
00055 }
00056 
00057 void TextLCD::cls() {
00058     writeCommand(0x01); // cls, and set cursor to 0
00059     wait(0.00164f);     // This command takes 1.64 ms
00060     //Thread::wait(2);
00061     locate(0, 0);
00062 }
00063 
00064 void TextLCD::locate(int column, int row) {
00065     _column = column;
00066     _row = row;
00067 }
00068 
00069 int TextLCD::_putc(int value) {
00070     if (value == '\n') {
00071         _column = 0;
00072         _row++;
00073         if (_row >= rows()) {
00074             _row = 0;
00075         }
00076     } else {
00077         character(_column, _row, value);
00078         _column++;
00079         if (_column >= columns()) {
00080             _column = 0;
00081             _row++;
00082             if (_row >= rows()) {
00083                 _row = 0;
00084             }
00085         }
00086     }
00087     return value;
00088 }
00089 
00090 int TextLCD::_getc() {
00091     return -1;
00092 }
00093 
00094 void TextLCD::writeByte(int value) {
00095     _d = value >> 4;
00096     wait(0.000040f); // most instructions take 40us
00097     //Thread::wait(1);
00098     _e = 0;
00099     wait(0.000040f);
00100     //Thread::wait(1);
00101     _e = 1;
00102     _d = value >> 0;
00103     wait(0.000040f);
00104     //Thread::wait(1);
00105     _e = 0;
00106     wait(0.000040f);  // most instructions take 40us
00107     //Thread::wait(1);
00108     _e = 1;
00109 }
00110 
00111 void TextLCD::writeCommand(int command) {
00112     _rs = 0;
00113     writeByte(command);
00114 }
00115 
00116 void TextLCD::writeData(int data) {
00117     _rs = 1;
00118     writeByte(data);
00119 }
00120 
00121 int TextLCD::address(int column, int row) {
00122     switch (_type) {
00123         case LCD20x4:
00124             switch (row) {
00125                 case 0:
00126                     return 0x80 + column;
00127                 case 1:
00128                     return 0xc0 + column;
00129                 case 2:
00130                     return 0x94 + column;
00131                 case 3:
00132                     return 0xd4 + column;
00133             }
00134         case LCD16x2B:
00135             return 0x80 + (row * 40) + column;
00136         case LCD16x2:
00137         case LCD20x2:
00138         default:
00139             return 0x80 + (row * 0x40) + column;
00140     }
00141 }
00142 
00143 int TextLCD::columns() {
00144     switch (_type) {
00145         case LCD20x4:
00146         case LCD20x2:
00147             return 20;
00148         case LCD16x2:
00149         case LCD16x2B:
00150         default:
00151             return 16;
00152     }
00153 }
00154 
00155 int TextLCD::rows() {
00156     switch (_type) {
00157         case LCD20x4:
00158             return 4;
00159         case LCD16x2:
00160         case LCD16x2B:
00161         case LCD20x2:
00162         default:
00163             return 2;
00164     }
00165 }
00166