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     }
00041     writeByte(0x2);     // 4-bit mode
00042     wait(0.000040f);    // most instructions take 40us
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::init(void)
00052 {
00053     _e  = 1;
00054     _rs = 0;            // command mode
00055 
00056     wait(0.015);        // Wait 15ms to ensure powered up
00057 
00058     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
00059     for (int i=0; i<3; i++) {
00060         writeByte(0x3);
00061         wait(0.00164);  // this command takes 1.64ms, so wait for it
00062     }
00063     writeByte(0x2);     // 4-bit mode
00064     wait(0.000040f);    // most instructions take 40us
00065 
00066     writeCommand(0x28); // Function set 001 BW N F - -
00067     writeCommand(0x0C);
00068     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00069 }
00070 
00071 
00072 void TextLCD::character(int column, int row, int c) {
00073     int a = address(column, row);
00074     writeCommand(a);
00075     writeData(c);
00076 }
00077 
00078 void TextLCD::cls() {
00079     writeCommand(0x01); // cls, and set cursor to 0
00080     wait(0.00164f);     // This command takes 1.64 ms
00081     locate(0, 0);
00082 }
00083 
00084 void TextLCD::locate(int column, int row) {
00085     _column = column;
00086     _row = row;
00087 }
00088 
00089 int TextLCD::_putc(int value) {
00090     if (value == '\n') {
00091         _column = 0;
00092         _row++;
00093         if (_row >= rows()) {
00094             _row = 0;
00095         }
00096     } else {
00097         character(_column, _row, value);
00098         _column++;
00099         if (_column >= columns()) {
00100             _column = 0;
00101             _row++;
00102             if (_row >= rows()) {
00103                 _row = 0;
00104             }
00105         }
00106     }
00107     return value;
00108 }
00109 
00110 int TextLCD::_getc() {
00111     return -1;
00112 }
00113 
00114 void TextLCD::writeByte(int value) {
00115     _d = value >> 4;
00116     wait(0.000040f); // most instructions take 40us
00117     _e = 0;
00118     wait(0.000040f);
00119     _e = 1;
00120     _d = value >> 0;
00121     wait(0.000040f);
00122     _e = 0;
00123     wait(0.000040f);  // most instructions take 40us
00124     _e = 1;
00125 }
00126 
00127 void TextLCD::writeCommand(int command) {
00128     _rs = 0;
00129     writeByte(command);
00130 }
00131 
00132 void TextLCD::writeData(int data) {
00133     _rs = 1;
00134     writeByte(data);
00135 }
00136 
00137 int TextLCD::address(int column, int row) {
00138     switch (_type) {
00139         case LCD20x4:
00140             switch (row) {
00141                 case 0:
00142                     return 0x80 + column;
00143                 case 1:
00144                     return 0xc0 + column;
00145                 case 2:
00146                     return 0x94 + column;
00147                 case 3:
00148                     return 0xd4 + column;
00149             }
00150         case LCD16x2B:
00151             return 0x80 + (row * 40) + column;
00152         case LCD16x2:
00153         case LCD20x2:
00154         default:
00155             return 0x80 + (row * 0x40) + column;
00156     }
00157 }
00158 
00159 int TextLCD::columns() {
00160     switch (_type) {
00161         case LCD20x4:
00162         case LCD20x2:
00163             return 20;
00164         case LCD16x2:
00165         case LCD16x2B:
00166         default:
00167             return 16;
00168     }
00169 }
00170 
00171 int TextLCD::rows() {
00172     switch (_type) {
00173         case LCD20x4:
00174             return 4;
00175         case LCD16x2:
00176         case LCD16x2B:
00177         case LCD20x2:
00178         default:
00179             return 2;
00180     }
00181 }