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 #define TIME_WAIT_POWER_UP_US   (150000) // Time to ensure reliable power-up (150 ms)
00027 #define TIME_WAIT_1_64_MS_US    (1640)   // Time 1.64 ms for duration of a command
00028 #define TIME_WAIT_40_US         (40)     // Time 40 us for duration of a command
00029 
00030 TextLCD::TextLCD(PinName rs, PinName e, PinName d4, PinName d5,
00031                  PinName d6, PinName d7, LCDType type) : _rs(rs),
00032         _e(e), _d(d4, d5, d6, d7),
00033         _type(type) {
00034 
00035     _e  = 1;
00036     _rs = 0;            // command mode
00037 
00038     wait_us(TIME_WAIT_POWER_UP_US);        // Wait to ensure powered up
00039 
00040     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
00041     for (int i=0; i<3; i++) {
00042         writeByte(0x3);
00043         wait_us(TIME_WAIT_1_64_MS_US);  // this command takes 1.64ms, so wait for it
00044     }
00045     writeByte(0x2);             // 4-bit mode
00046     wait_us(TIME_WAIT_40_US);   // most instructions take 40us
00047 
00048     writeCommand(0x28); // Function set 001 BW N F - -
00049     writeCommand(0x0C);
00050     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00051     cls();
00052 }
00053 
00054 void TextLCD::character(int column, int row, int c) {
00055     int a = address(column, row);
00056     writeCommand(a);
00057     writeData(c);
00058 }
00059 
00060 void TextLCD::cls() {
00061     writeCommand(0x01); // cls, and set cursor to 0
00062     wait_us(TIME_WAIT_1_64_MS_US);     // This command takes 1.64 ms
00063     locate(0, 0);
00064 }
00065 
00066 void TextLCD::locate(int column, int row) {
00067     _column = column;
00068     _row = row;
00069 }
00070 
00071 int TextLCD::_putc(int value) {
00072     if (value == '\n') {
00073         _column = 0;
00074         _row++;
00075         if (_row >= rows()) {
00076             _row = 0;
00077         }
00078     } else {
00079         character(_column, _row, value);
00080         _column++;
00081         if (_column >= columns()) {
00082             _column = 0;
00083             _row++;
00084             if (_row >= rows()) {
00085                 _row = 0;
00086             }
00087         }
00088     }
00089     return value;
00090 }
00091 
00092 int TextLCD::_getc() {
00093     return -1;
00094 }
00095 
00096 void TextLCD::writeByte(int value) {
00097     _d = value >> 4;
00098     wait_us(TIME_WAIT_40_US); // most instructions take 40us
00099     _e = 0;
00100     wait_us(TIME_WAIT_40_US); // most instructions take 40us
00101     _e = 1;
00102     _d = value >> 0;
00103     wait_us(TIME_WAIT_40_US); // most instructions take 40us
00104     _e = 0;
00105     wait_us(TIME_WAIT_40_US); // most instructions take 40us
00106     _e = 1;
00107 }
00108 
00109 void TextLCD::writeCommand(int command) {
00110     _rs = 0;
00111     writeByte(command);
00112 }
00113 
00114 void TextLCD::writeData(int data) {
00115     _rs = 1;
00116     writeByte(data);
00117 }
00118 
00119 int TextLCD::address(int column, int row) {
00120     switch (_type) {
00121         case LCD20x4:
00122             switch (row) {
00123                 case 0:
00124                     return 0x80 + column;
00125                 case 1:
00126                     return 0xc0 + column;
00127                 case 2:
00128                     return 0x94 + column;
00129                 case 3:
00130                     return 0xd4 + column;
00131             }
00132         case LCD16x2B:
00133             return 0x80 + (row * 40) + column;
00134         case LCD16x2:
00135         case LCD20x2:
00136         default:
00137             return 0x80 + (row * 0x40) + column;
00138     }
00139 }
00140 
00141 int TextLCD::columns() {
00142     switch (_type) {
00143         case LCD20x4:
00144         case LCD20x2:
00145             return 20;
00146         case LCD16x2:
00147         case LCD16x2B:
00148         default:
00149             return 16;
00150     }
00151 }
00152 
00153 int TextLCD::rows() {
00154     switch (_type) {
00155         case LCD20x4:
00156             return 4;
00157         case LCD16x2:
00158         case LCD16x2B:
00159         case LCD20x2:
00160         default:
00161             return 2;
00162     }
00163 }