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 /*
00024  * Comment: Added support for LCD40x2 and LCD8x2
00025  * Name:    davervw
00026  * Date:    02/26/2011
00027  */
00028 
00029 #include "TextLCD.h"
00030 #include "mbed.h"
00031 
00032 TextLCD::TextLCD(PinName rs, PinName e, PinName d4, PinName d5,
00033                  PinName d6, PinName d7, LCDType type) : _rs(rs),
00034         _e(e), _d(d4, d5, d6, d7),
00035         _type(type) {
00036 
00037     _e  = 1;
00038     _rs = 0;            // command mode
00039 
00040     wait(0.015);        // Wait 15ms to ensure powered up
00041 
00042     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
00043     for (int i=0; i<3; i++) {
00044         writeByte(0x3);
00045         wait(0.00164);  // this command takes 1.64ms, so wait for it
00046     }
00047     writeByte(0x2);     // 4-bit mode
00048     wait(0.000040f);    // most instructions take 40us
00049 
00050     writeCommand(0x28); // Function set 001 BW N F - -
00051     writeCommand(0x0C);
00052     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00053     cls();
00054 }
00055 
00056 void TextLCD::character(int column, int row, int c) {
00057     int a = address(column, row);
00058     writeCommand(a);
00059     writeData(c);
00060 }
00061 
00062 void TextLCD::cls() {
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     _column = column;
00070     _row = row;
00071 }
00072 
00073 int TextLCD::_putc(int value) {
00074     if (value == '\n') {
00075         _column = 0;
00076         _row++;
00077         if (_row >= rows()) {
00078             _row = 0;
00079         }
00080     } else {
00081         character(_column, _row, value);
00082         _column++;
00083         if (_column >= columns()) {
00084             _column = 0;
00085             _row++;
00086             if (_row >= rows()) {
00087                 _row = 0;
00088             }
00089         }
00090     }
00091     return value;
00092 }
00093 
00094 int TextLCD::_getc() {
00095     return -1;
00096 }
00097 
00098 void TextLCD::writeByte(int value) {
00099     _d = value >> 4;
00100     wait(0.000040f); // most instructions take 40us
00101     _e = 0;
00102     wait(0.000040f);
00103     _e = 1;
00104     _d = value >> 0;
00105     wait(0.000040f);
00106     _e = 0;
00107     wait(0.000040f);  // most instructions take 40us
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 LCD40x2:
00138         case LCD20x2:
00139         case LCD8x2:
00140         default:
00141             return 0x80 + (row * 0x40) + column;
00142     }
00143 }
00144 
00145 int TextLCD::columns() {
00146     switch (_type) {
00147         case LCD20x4:
00148         case LCD20x2:
00149             return 20;
00150         case LCD40x2:
00151             return 40;
00152         case LCD8x2:
00153             return 8;
00154         case LCD16x2:
00155         case LCD16x2B:
00156         default:
00157             return 16;
00158     }
00159 }
00160 
00161 int TextLCD::rows() {
00162     switch (_type) {
00163         case LCD20x4:
00164             return 4;
00165         case LCD8x2:
00166         case LCD16x2:
00167         case LCD16x2B:
00168         case LCD20x2:
00169         case LCD40x2:
00170         default:
00171             return 2;
00172     }
00173 }