TextLCD.cpp

00001 /* mbed TextLCD Library, for a 4-bit LCD based on HD44780
00002  * Copyright (c) 2007-2010, sford
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 rw, PinName e, PinName d0, PinName d1,
00027                  PinName d2, PinName d3, LCDType type) : _rs(rs), _rw(rw),
00028         _e(e), _d(d0, d1, d2, d3),
00029         _type(type) {
00030 
00031     _rw  = 0;
00032     _e  = 1;
00033     _rs = 0;            // command mode
00034     _d.output();
00035     
00036     wait(0.015);        // Wait 15ms to ensure powered up
00037 
00038     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
00039     for (int i=0; i<3; i++) {
00040         writeByte(0x3);
00041         wait(0.00164);  // this command takes 1.64ms, so wait for it
00042     }
00043     writeByte(0x2);     // 4-bit mode
00044     wait(0.000040f);    // most instructions take 40us
00045 
00046     writeCommand(0x28); // Function set 001 BW N F - -
00047     writeCommand(0x0C);
00048     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00049     cls();
00050 }
00051 
00052 void TextLCD::character(int column, int row, int c) {
00053     int a = address(column, row);
00054     writeCommand(a);
00055     writeData(c);
00056 }
00057 
00058 void TextLCD::cls() {
00059     writeCommand(0x01); // cls, and set cursor to 0
00060     wait(0.00164f);     // This command takes 1.64 ms
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     _rw = 0;
00096     
00097     _d = value >> 4;
00098     wait(0.000040f); // most instructions take 40us
00099     _e = 0;
00100     wait(0.000040f);
00101     _e = 1;
00102     _d = value >> 0;
00103     wait(0.000040f);
00104     _e = 0;
00105     wait(0.000040f);  // most instructions take 40us
00106     _e = 1;
00107 }
00108 
00109 void TextLCD::writeCommand(int command) {
00110     _rs = 0;
00111     writeByte(command);
00112 }
00113 
00114 void TextLCD::writeData(int data) {
00115     _rs = 1;
00116     writeByte(data);
00117 }
00118 
00119 int TextLCD::address(int column, int row) {
00120     switch (_type) {
00121         case LCD20x4:
00122             switch (row) {
00123                 case 0:
00124                     return 0x80 + column;
00125                 case 1:
00126                     return 0xc0 + column;
00127                 case 2:
00128                     return 0x94 + column;
00129                 case 3:
00130                     return 0xd4 + column;
00131             }
00132         case LCD16x2B:
00133             return 0x80 + (row * 40) + column;
00134         case LCD16x2:
00135         case LCD20x2:
00136         default:
00137             return 0x80 + (row * 0x40) + column;
00138     }
00139 }
00140 
00141 int TextLCD::columns() {
00142     switch (_type) {
00143         case LCD20x4:
00144         case LCD20x2:
00145             return 20;
00146         case LCD16x2:
00147         case LCD16x2B:
00148         default:
00149             return 16;
00150     }
00151 }
00152 
00153 int TextLCD::rows() {
00154     switch (_type) {
00155         case LCD20x4:
00156             return 4;
00157         case LCD16x2:
00158         case LCD16x2B:
00159         case LCD20x2:
00160         default:
00161             return 2;
00162     }
00163 }