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 d0, PinName d1,
00027                  PinName d2, PinName d3, LCDType type) : _rs(rs), _rw(rw),
00028         _e(e), _d(d0, d1, d2, d3), _type(type) {
00029     _rs = 0;            // command mode
00030     _rw = 0;
00031     _e  = 0;            
00032     _d.output();        // data out
00033  
00034     wait(0.05);        // Wait 50ms 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         _e = 1;
00039         wait(0.000001f);
00040         _d = 0x3;
00041         wait(0.000001f); 
00042         _e = 0;
00043         wait(0.004f); // 4ms
00044        }
00045     _e = 1;
00046     wait(0.000001f);
00047     _d = 0x2;           // 4 Bit mode
00048     wait(0.000001f); 
00049     _e = 0;
00050     
00051     writeCommand(0x28); // Function set 4 Bit, 2Line, 5*7
00052     writeCommand(0x08); // Display off
00053     writeCommand(0x01); // clear Display
00054     writeCommand(0x04); // cursor right, Display is not shifted
00055     writeCommand(0x0C); // Display on , Cursor off 
00056 }
00057  
00058 void TextLCD::character(int column, int row, int c) {
00059     int a = address(column, row);
00060     writeCommand(a);
00061     writeData(c);
00062 }
00063  
00064 void TextLCD::cls() {
00065     writeCommand(0x01); // cls, and set cursor to 0
00066     wait(0.00164f);
00067     locate(0, 0);
00068 }
00069  
00070 void TextLCD::locate(int column, int row) {
00071     _column = column;
00072     _row = row;
00073 }
00074  
00075 /**int TextLCD::putc(int values) {
00076     return(_putc(values));
00077  }**/ 
00078  
00079 int TextLCD::_putc(int value) {
00080     if (value == '\n') {
00081         _column = 0;
00082         _row++;
00083         if (_row >= rows()) {
00084             _row = 0;
00085         }
00086     } else {
00087         character(_column, _row, value);
00088         _column++;
00089         if (_column >= columns()) {
00090             _column = 0;
00091             _row++;
00092             if (_row >= rows()) {
00093                 _row = 0;
00094             }
00095         }
00096     }
00097     return value;
00098 }
00099  
00100 int TextLCD::_getc() {
00101     int a = address(_column, _row);
00102     writeCommand(a);
00103     return (readData());
00104 }
00105  
00106 void TextLCD::writeByte(int value) {
00107    _e = 1;
00108     wait(0.000040f);    
00109     _d = value >> 4;
00110     wait(0.000040f);
00111     _e = 0;
00112     wait(0.000040f);
00113     _e = 1;
00114     wait(0.000040f);
00115     _d = value >> 0;
00116     wait(0.000040f);
00117     _e = 0;
00118 }
00119  
00120 void TextLCD::writeCommand(int command) {
00121     waitBusy();  // check if display is ready 
00122     _rs = 0;
00123     writeByte(command);
00124 }
00125  
00126 int TextLCD::readData(){
00127     int input;
00128     waitBusy();
00129     _rw = 1;
00130     _rs = 1;
00131      wait(0.000001f);
00132     _d.input();  // switch Data port to input
00133     _e = 1;
00134     wait(0.000001f);
00135     input = _d.read() << 4; // high nibble
00136     _e = 0;
00137      wait(0.000001f);
00138     _e = 1;
00139     wait(0.000001f);
00140     input = input | _d.read(); // low nibble
00141     _e = 0;   
00142     return (input);
00143 }
00144  
00145  void TextLCD::waitBusy(){
00146     int input;
00147     _rw = 1;
00148     _rs = 0;
00149     wait(0.000001f);
00150     _d.input();      // switch Data port to input
00151     do{ 
00152         _e = 1;
00153         wait(0.000001f);
00154         input = _d.read();              
00155         _e = 0;
00156         wait(0.000001f);
00157         _e = 1;
00158         wait(0.000001f);  
00159         _e = 0;
00160        }while((0x8 & input) == 0x8);  // wait until display is ready
00161     _rw = 0;
00162     _d.output();      // switch port back to output  
00163  }
00164  
00165 void TextLCD::writeData(int data) {
00166     waitBusy();
00167     _rs = 1;
00168     writeByte(data);
00169 }
00170  
00171  
00172 // set user defined char 
00173 void  TextLCD::writeCGRAM(int address, int pattern[8]){
00174     int i;
00175     address = address & 0x07;  //max 8 char
00176     for(i=0;i<8;i++){
00177         waitBusy();  // check if display is ready 
00178         _rs = 0;
00179         writeByte(0x40 + address * 8 + i);
00180         writeData(pattern[i]);
00181         }
00182 }   
00183         
00184  
00185 int TextLCD::address(int column, int row) {
00186     switch (_type) {
00187         case LCD20x4:
00188             switch (row) {
00189                 case 0:
00190                     return 0x80 + column;
00191                 case 1:
00192                     return 0xc0 + column;
00193                 case 2:
00194                     return 0x94 + column;
00195                 case 3:
00196                     return 0xd4 + column;
00197             }
00198         case LCD16x2B:
00199             return 0x80 + (row * 40) + column;
00200         case LCD16x2:
00201         case LCD20x2:
00202         default:
00203             return 0x80 + (row * 0x40) + column;
00204     }
00205 }
00206  
00207 int TextLCD::columns() {
00208     switch (_type) {
00209         case LCD20x4:
00210         case LCD20x2:
00211             return 20;
00212         case LCD16x2:
00213         case LCD16x2B:
00214         default:
00215             return 16;
00216     }
00217 }
00218  
00219 int TextLCD::rows() {
00220     switch (_type) {
00221         case LCD20x4:
00222             return 4;
00223         case LCD16x2:
00224         case LCD16x2B:
00225         case LCD20x2:
00226         default:
00227             return 2;
00228     }
00229 }