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 rw, PinName e, PinName d4, PinName d5,
00027                  PinName d6, PinName d7, LCDType type) : _rs(rs), _rw(rw),
00028         _e(e), _d(d4, d5, d6, d7),
00029         _type(type) {
00030 
00031     _rw = 0;
00032     _e  = 1;
00033     _rs = 0;            // command mode
00034 
00035     wait(0.015);        // Wait 15ms to ensure powered up
00036 
00037     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
00038     for (int i=0; i<3; i++) {
00039         writeNibble(0x3);        
00040         wait(0.00164);  // this command takes 1.64ms, so wait for it
00041     }
00042     
00043     writeNibble(0x2);     // 4-bit mode    
00044 
00045     writeCommand(0x28); // Function set 001 BW N F - -
00046     writeCommand(0x0C);
00047     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00048     cls();
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     writeNibble(value >> 4);
00095     writeNibble(value >> 0);
00096 }
00097 
00098 void TextLCD::writeCommand(int command) {
00099     _rs = 0;
00100     writeByte(command);
00101 }
00102 
00103 void TextLCD::clock(void) {
00104     wait(0.000040f);
00105     _e = 0;
00106     wait(0.000040f);
00107     _e = 1;
00108 }
00109 
00110 void TextLCD::writeNibble(int data) {
00111     _d = data;
00112     clock();
00113 }
00114 
00115 void TextLCD::writeData(int data) {
00116     _rs = 1;
00117     writeByte(data);
00118 }
00119 
00120 int TextLCD::address(int column, int row) {
00121     switch (_type) {
00122         case LCD20x4:
00123             switch (row) {
00124                 case 0:
00125                     return 0x80 + column;
00126                 case 1:
00127                     return 0xc0 + column;
00128                 case 2:
00129                     return 0x94 + column;
00130                 case 3:
00131                     return 0xd4 + column;
00132             }
00133         case LCD16x2B:
00134             return 0x80 + (row * 40) + column;
00135         case LCD16x2:
00136         case LCD20x2:
00137         default:
00138             return 0x80 + (row * 0x40) + column;
00139     }
00140 }
00141 
00142 int TextLCD::columns() {
00143     switch (_type) {
00144         case LCD20x4:
00145         case LCD20x2:
00146             return 20;
00147         case LCD16x2:
00148         case LCD16x2B:
00149         default:
00150             return 16;
00151     }
00152 }
00153 
00154 int TextLCD::rows() {
00155     switch (_type) {
00156         case LCD20x4:
00157             return 4;
00158         case LCD16x2:
00159         case LCD16x2B:
00160         case LCD20x2:
00161         default:
00162             return 2;
00163     }
00164 }