TextLCD_SR4.cpp

00001 /* mbed TextLCD_SR4 Library, for a 4-bit LCD based on HD44780
00002  * Copyright (c) 2007-2010, sford
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 /*
00024  * Modified for http://mbed.org/users/shintamainjp/notebook/textlcd_sr4_en/
00025  * Shinichiro Nakamura
00026  */
00027 
00028 #include "TextLCD_SR4.h"
00029 #include "mbed.h"
00030 
00031 TextLCD_SR4::TextLCD_SR4(PinName rs, PinName e, PinName dat, PinName clk, LCDType type)
00032         : _rs(rs), _e(e), _dat(dat), _clk(clk), _type(type) {
00033 
00034     _e  = 1;
00035     _rs = 0;            // command mode
00036 
00037     wait(0.015);        // Wait 15ms to ensure powered up
00038 
00039     // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
00040     for (int i = 0; i < 3; i++) {
00041         writeByte(0x3);
00042         wait(0.00164);  // this command takes 1.64ms, so wait for it
00043     }
00044     writeByte(0x2);     // 4-bit mode
00045     wait(0.000040f);    // most instructions take 40us
00046 
00047     writeCommand(0x28); // Function set 001 BW N F - -
00048     writeCommand(0x0C);
00049     writeCommand(0x6);  // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
00050     cls();
00051 }
00052 
00053 void TextLCD_SR4::character(int column, int row, int c) {
00054     int a = address(column, row);
00055     writeCommand(a);
00056     writeData(c);
00057 }
00058 
00059 void TextLCD_SR4::cls() {
00060     writeCommand(0x01); // cls, and set cursor to 0
00061     wait(0.00164f);     // This command takes 1.64 ms
00062     locate(0, 0);
00063 }
00064 
00065 void TextLCD_SR4::locate(int column, int row) {
00066     _column = column;
00067     _row = row;
00068 }
00069 
00070 int TextLCD_SR4::_putc(int value) {
00071     if (value == '\n') {
00072         _column = 0;
00073         _row++;
00074         if (_row >= rows()) {
00075             _row = 0;
00076         }
00077     } else {
00078         character(_column, _row, value);
00079         _column++;
00080         if (_column >= columns()) {
00081             _column = 0;
00082             _row++;
00083             if (_row >= rows()) {
00084                 _row = 0;
00085             }
00086         }
00087     }
00088     return value;
00089 }
00090 
00091 int TextLCD_SR4::_getc() {
00092     return -1;
00093 }
00094 
00095 void TextLCD_SR4::writeByte(int value) {
00096     writeToShiftRegister(value << 0);
00097     wait(0.000040f); // most instructions take 40us
00098     _e = 0;
00099     wait(0.000040f);
00100     _e = 1;
00101     writeToShiftRegister(value << 4);
00102     wait(0.000040f);
00103     _e = 0;
00104     wait(0.000040f);  // most instructions take 40us
00105     _e = 1;
00106 }
00107 
00108 void TextLCD_SR4::writeToShiftRegister(int value) {
00109     /*
00110      * MSB first.
00111      */
00112     for (int i = 0; i < 8; i++) {
00113         if (value & (1 << (7 - i))) {
00114             _dat = 1;
00115         } else {
00116             _dat = 0;
00117         }
00118         _clk = 1;
00119         wait_us(1);
00120         _clk = 0;
00121         wait_us(1);
00122     }
00123 }
00124 
00125 void TextLCD_SR4::writeCommand(int command) {
00126     _rs = 0;
00127     writeByte(command);
00128 }
00129 
00130 void TextLCD_SR4::writeData(int data) {
00131     _rs = 1;
00132     writeByte(data);
00133 }
00134 
00135 int TextLCD_SR4::address(int column, int row) {
00136     switch (_type) {
00137         case LCD20x4:
00138             switch (row) {
00139                 case 0:
00140                     return 0x80 + column;
00141                 case 1:
00142                     return 0xc0 + column;
00143                 case 2:
00144                     return 0x94 + column;
00145                 case 3:
00146                     return 0xd4 + column;
00147             }
00148         case LCD16x2B:
00149             return 0x80 + (row * 40) + column;
00150         case LCD16x2:
00151         case LCD20x2:
00152         default:
00153             return 0x80 + (row * 0x40) + column;
00154     }
00155 }
00156 
00157 int TextLCD_SR4::columns() {
00158     switch (_type) {
00159         case LCD20x4:
00160         case LCD20x2:
00161             return 20;
00162         case LCD16x2:
00163         case LCD16x2B:
00164         default:
00165             return 16;
00166     }
00167 }
00168 
00169 int TextLCD_SR4::rows() {
00170     switch (_type) {
00171         case LCD20x4:
00172             return 4;
00173         case LCD16x2:
00174         case LCD16x2B:
00175         case LCD20x2:
00176         default:
00177             return 2;
00178     }
00179 }