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,1), _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     }
00041     writeByte(0x2);     // 4-bit mode
00042     wait(0.00164);    // 1.64ms
00043 
00044     writeCommand(0x28); // Function set 001 BW N F - -
00045     writeCommand(0x0C);
00046     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00047     cls();
00048 
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     locate(0, 0);
00061 }
00062 
00063 void TextLCD::locate(int column, int row) {
00064     _column = column;
00065     _row = row;
00066 }
00067 
00068 int TextLCD::_putc(int value) {
00069     if (value == '\n') {
00070         _column = 0;
00071         _row++;
00072         if (_row >= rows()) {
00073             _row = 0;
00074         }
00075     } else {
00076         character(_column, _row, value);
00077         _column++;
00078         if (_column >= columns()) {
00079             _column = 0;
00080             _row++;
00081             if (_row >= rows()) {
00082                 _row = 0;
00083             }
00084         }
00085     }
00086     return value;
00087 }
00088 
00089 int TextLCD::_getc() {
00090     return -1;
00091 }
00092 
00093 void TextLCD::writeByte(int value) {
00094     _d = value >> 4;
00095     wait(0.000040f); // most instructions take 40us
00096     _e = 0;
00097     wait(0.000040f);
00098     _e = 1;
00099     _d = value >> 0;
00100     wait(0.000040f);
00101     _e = 0;
00102     wait(0.000040f);  // most instructions take 40us
00103     _e = 1;
00104 }
00105 
00106 void TextLCD::writeCommand(int command) {
00107     _rs = 0;
00108     writeByte(command);
00109 }
00110 
00111 void TextLCD::writeData(int data) {
00112     _rs = 1;
00113     writeByte(data);
00114 }
00115 
00116 int TextLCD::address(int column, int row) {
00117     switch (_type) {
00118         case LCD20x4:
00119             switch (row) {
00120                 case 0:
00121                     return 0x80 + column;
00122                 case 1:
00123                     return 0xc0 + column;
00124                 case 2:
00125                     return 0x94 + column;
00126                 case 3:
00127                     return 0xd4 + column;
00128             }
00129         case LCD16x2B:
00130             return 0x80 + (row * 40) + column;
00131         case LCD16x2:
00132         case LCD20x2:
00133         default:
00134             return 0x80 + (row * 0x40) + column;
00135     }
00136 }
00137 
00138 int TextLCD::columns() {
00139     switch (_type) {
00140         case LCD20x4:
00141         case LCD20x2:
00142             return 20;
00143         case LCD16x2:
00144         case LCD16x2B:
00145         default:
00146             return 16;
00147     }
00148 }
00149 
00150 int TextLCD::rows() {
00151     switch (_type) {
00152         case LCD20x4:
00153             return 4;
00154         case LCD16x2:
00155         case LCD16x2B:
00156         case LCD20x2:
00157         default:
00158             return 2;
00159     }
00160 }