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 void TextLCD::character(int column, int row, int c) {
00051     int a = address(column, row);
00052     writeCommand(a);
00053     writeData(c);
00054 }
00055 
00056 void TextLCD::cls() {
00057     writeCommand(0x01); // cls, and set cursor to 0
00058     wait(0.00164f);     // This command takes 1.64 ms
00059     locate(0, 0);
00060 }
00061 
00062 void TextLCD::locate(int column, int row) {
00063     _column = column;
00064     _row = row;
00065 }
00066 
00067 int TextLCD::_putc(int value) {
00068     if (value == '\n') {
00069         _column = 0;
00070         _row++;
00071         if (_row >= rows()) {
00072             _row = 0;
00073         }
00074     } else {
00075         character(_column, _row, value);
00076         _column++;
00077         if (_column >= columns()) {
00078             _column = 0;
00079             _row++;
00080             if (_row >= rows()) {
00081                 _row = 0;
00082             }
00083         }
00084     }
00085     return value;
00086 }
00087 
00088 int TextLCD::_getc() {
00089     return -1;
00090 }
00091 
00092 void TextLCD::writeByte(int value) {
00093     _d = value >> 4;
00094     wait(0.000040f); // most instructions take 40us
00095     _e = 0;
00096     wait(0.000040f);
00097     _e = 1;
00098     _d = value >> 0;
00099     wait(0.000040f);
00100     _e = 0;
00101     wait(0.000040f);  // most instructions take 40us
00102     _e = 1;
00103 }
00104 
00105 void TextLCD::writeCommand(int command) {
00106     _rs = 0;
00107     writeByte(command);
00108 }
00109 
00110 void TextLCD::writeData(int data) {
00111     _rs = 1;
00112     writeByte(data);
00113 }
00114 
00115 int TextLCD::address(int column, int row) {
00116     switch (_type) {
00117         case LCD20x4:
00118             switch (row) {
00119                 case 0:
00120                     return 0x80 + column;
00121                 case 1:
00122                     return 0xc0 + column;
00123                 case 2:
00124                     return 0x94 + column;
00125                 case 3:
00126                     return 0xd4 + column;
00127             }
00128         case LCD16x2B:
00129             return 0x80 + (row * 40) + column;
00130         case LCD16x2:
00131         case LCD20x2:
00132         default:
00133             return 0x80 + (row * 0x40) + column;
00134     }
00135 }
00136 
00137 int TextLCD::columns() {
00138     switch (_type) {
00139         case LCD20x4:
00140         case LCD20x2:
00141             return 20;
00142         case LCD16x2:
00143         case LCD16x2B:
00144         default:
00145             return 16;
00146     }
00147 }
00148 
00149 int TextLCD::rows() {
00150     switch (_type) {
00151         case LCD20x4:
00152             return 4;
00153         case LCD16x2:
00154         case LCD16x2B:
00155         case LCD20x2:
00156         default:
00157             return 2;
00158     }
00159 }