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 }
00032 
00033 void TextLCD::start()
00034 {
00035     _e  = 1;
00036     _rs = 0;            // command mode
00037 
00038     wait(0.015);        // Wait 15ms to ensure powered up
00039 
00040     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
00041     for (int i=0; i<3; i++) {
00042         writeByte(0x3);
00043         wait(0.00164);  // this command takes 1.64ms, so wait for it
00044     }
00045     writeByte(0x2);     // 4-bit mode
00046     wait(0.000040f);    // most instructions take 40us
00047 
00048     writeCommand(0x28); // Function set 001 BW N F - -
00049     writeCommand(0x0C);
00050     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00051     cls();
00052 }
00053 
00054 void TextLCD::character(int column, int row, int c)
00055 {
00056     int a = address(column, row);
00057     writeCommand(a);
00058     writeData(c);
00059 }
00060 
00061 void TextLCD::cls()
00062 {
00063     writeCommand(0x01); // cls, and set cursor to 0
00064     wait(0.00164f);     // This command takes 1.64 ms
00065     locate(0, 0);
00066 }
00067 
00068 void TextLCD::locate(int column, int row)
00069 {
00070     _column = column;
00071     _row = row;
00072 }
00073 
00074 int TextLCD::_putc(int value)
00075 {
00076     if (value == '\n') {
00077         _column = 0;
00078         _row++;
00079         if (_row >= rows()) {
00080             _row = 0;
00081         }
00082     } else {
00083         character(_column, _row, value);
00084         _column++;
00085         if (_column >= columns()) {
00086             _column = 0;
00087             _row++;
00088             if (_row >= rows()) {
00089                 _row = 0;
00090             }
00091         }
00092     }
00093     return value;
00094 }
00095 
00096 int TextLCD::_getc()
00097 {
00098     return -1;
00099 }
00100 
00101 void TextLCD::writeByte(int value)
00102 {
00103     _d = value >> 4;
00104     wait(0.000040f); // most instructions take 40us
00105     _e = 0;
00106     wait(0.000040f);
00107     _e = 1;
00108     _d = value >> 0;
00109     wait(0.000040f);
00110     _e = 0;
00111     wait(0.000040f);  // most instructions take 40us
00112     _e = 1;
00113 }
00114 
00115 void TextLCD::writeCommand(int command)
00116 {
00117     _rs = 0;
00118     writeByte(command);
00119 }
00120 
00121 void TextLCD::writeData(int data)
00122 {
00123     _rs = 1;
00124     writeByte(data);
00125 }
00126 
00127 int TextLCD::address(int column, int row)
00128 {
00129     switch (_type) {
00130         case LCD20x4:
00131             switch (row) {
00132                 case 0:
00133                     return 0x80 + column;
00134                 case 1:
00135                     return 0xc0 + column;
00136                 case 2:
00137                     return 0x94 + column;
00138                 case 3:
00139                     return 0xd4 + column;
00140             }
00141         case LCD16x2B:
00142             return 0x80 + (row * 40) + column;
00143         case LCD16x2:
00144         case LCD20x2:
00145         default:
00146             return 0x80 + (row * 0x40) + column;
00147     }
00148 }
00149 
00150 int TextLCD::columns()
00151 {
00152     switch (_type) {
00153         case LCD20x4:
00154         case LCD20x2:
00155             return 20;
00156         case LCD16x2:
00157         case LCD16x2B:
00158         default:
00159             return 16;
00160     }
00161 }
00162 
00163 int TextLCD::rows()
00164 {
00165     switch (_type) {
00166         case LCD20x4:
00167             return 4;
00168         case LCD16x2:
00169         case LCD16x2B:
00170         case LCD20x2:
00171         default:
00172             return 2;
00173     }
00174 }