LCD.cpp

00001 /* mbed LCD Library, for a 4-bit LCD based on HD44780
00002  * Copyright (c) 2007-2010, hb9gaa
00003  *
00004  */
00005 
00006 #include "LCD.h"
00007 #include "mbed.h"
00008 
00009 TextLCD::TextLCD(PinName rs, PinName rw, PinName e, PinName d0, PinName d1,
00010                  PinName d2, PinName d3, LCDType type) : _rs(rs), _rw(rw),
00011         _e(e), _d(d0, d1, d2, d3),
00012         _type(type) {
00013 
00014     _e  = 1;
00015     _rw = 0;
00016     _rs = 0;            // command mode
00017 
00018      wait(0.015);        // Wait 15ms to ensure powered up
00019 
00020     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
00021     for (int i=0; i<3; i++) {
00022         writeByte(0x3);
00023         wait(0.00164);  // this command takes 1.64ms, so wait for it
00024     }
00025     writeByte(0x2);     // 4-bit mode
00026     wait(0.0001f);    // most instructions take 100us
00027 
00028     writeCommand(0x28); // Function set 001 BW N F - -
00029     writeCommand(0x0C);
00030     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00031     cls();
00032 }
00033 
00034 void TextLCD::character(int column, int row, int c) {
00035     int a = address(column, row);
00036     writeCommand(a);
00037     writeData(c);
00038 }
00039 
00040 void TextLCD::cls() {
00041     writeCommand(0x01); // cls, and set cursor to 0
00042     wait(0.004100f);    // This command takes 4.1 ms
00043     locate(0, 0);
00044 }
00045 
00046 void TextLCD::locate(int row, int column) {
00047     _row = row;
00048     _column = column;
00049 }
00050 
00051 int TextLCD::_putc(int value) {
00052     if (value == '\n') {
00053         _column = 0;
00054         _row++;
00055         if (_row >= rows()) {
00056             _row = 0;
00057         }
00058     } else {
00059         character(_column, _row, value);
00060         _column++;
00061         if (_column >= columns()) {
00062             _column = 0;
00063             _row++;
00064             if (_row >= rows()) {
00065                 _row = 0;
00066             }
00067         }
00068     }
00069     return value;
00070 }
00071 
00072 int TextLCD::_getc() {
00073     return -1;
00074 }
00075 
00076 void TextLCD::writeByte(int value) {
00077     _d = value >> 4;
00078     wait(0.0001); // most instructions take 100us
00079     _e = 0;
00080     wait(0.0001);
00081     _e = 1;
00082     _d = value >> 0;
00083     wait(0.0001);
00084     _e = 0;
00085     wait(0.0001);  // most instructions take 100us
00086     _e = 1;
00087 }
00088 
00089 void TextLCD::writeCommand(int command) {
00090     _rs = 0;
00091     writeByte(command);
00092 }
00093 
00094 void TextLCD::writeData(int data) {
00095     _rs = 1;
00096     writeByte(data);
00097 }
00098 
00099 int TextLCD::address(int column, int row) {
00100     switch (_type) {
00101         case LCD20x4:
00102             switch (row) {
00103                 case 0:
00104                     return 0x80 + column;
00105                 case 1:
00106                     return 0xc0 + column;
00107                 case 2:
00108                     return 0x94 + column;
00109                 case 3:
00110                     return 0xd4 + column;
00111             }
00112         case LCD16x2B:
00113             return 0x80 + (row * 40) + column;
00114         case LCD16x2:
00115         case LCD20x2:
00116         default:
00117             return 0x80 + (row * 0x40) + column;
00118     }
00119 }
00120 
00121 int TextLCD::columns() {
00122     switch (_type) {
00123         case LCD20x4:
00124         case LCD20x2:
00125             return 20;
00126         case LCD16x2:
00127         case LCD16x2B:
00128         default:
00129             return 16;
00130     }
00131 }
00132 
00133 int TextLCD::rows() {
00134     switch (_type) {
00135         case LCD20x4:
00136             return 4;
00137         case LCD16x2:
00138         case LCD16x2B:
00139         case LCD20x2:
00140         default:
00141             return 2;
00142     }
00143 }