Tianyang Chen
HW
Fork of
TextLCD
by 
Simon Ford
TextLCD.cpp@1:ac48b187213c, 2010-05-27 (annotated)
- Committer:
- simon
- Date:
- Thu May 27 13:44:15 2010 +0000
- Revision:
- 1:ac48b187213c
- Parent:
- 0:edfb85c53631
- Child:
- 2:227356c7d12c
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| simon | 1:ac48b187213c | 1 | /* mbed TextLCD Library, for a 4-bit LCD based on HD44780 |
| simon | 1:ac48b187213c | 2 | * Copyright (c) 2007-2010, sford |
| simon | 1:ac48b187213c | 3 | * |
| simon | 1:ac48b187213c | 4 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| simon | 1:ac48b187213c | 5 | * of this software and associated documentation files (the "Software"), to deal |
| simon | 1:ac48b187213c | 6 | * in the Software without restriction, including without limitation the rights |
| simon | 1:ac48b187213c | 7 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| simon | 1:ac48b187213c | 8 | * copies of the Software, and to permit persons to whom the Software is |
| simon | 1:ac48b187213c | 9 | * furnished to do so, subject to the following conditions: |
| simon | 1:ac48b187213c | 10 | * |
| simon | 1:ac48b187213c | 11 | * The above copyright notice and this permission notice shall be included in |
| simon | 1:ac48b187213c | 12 | * all copies or substantial portions of the Software. |
| simon | 1:ac48b187213c | 13 | * |
| simon | 1:ac48b187213c | 14 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| simon | 1:ac48b187213c | 15 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| simon | 1:ac48b187213c | 16 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| simon | 1:ac48b187213c | 17 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| simon | 1:ac48b187213c | 18 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| simon | 1:ac48b187213c | 19 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| simon | 1:ac48b187213c | 20 | * THE SOFTWARE. |
| simon | 1:ac48b187213c | 21 | */ |
| simon | 1:ac48b187213c | 22 | |
| simon | 1:ac48b187213c | 23 | #include "TextLCD.h" |
| simon | 1:ac48b187213c | 24 | #include "mbed.h" |
| simon | 1:ac48b187213c | 25 | |
| simon | 1:ac48b187213c | 26 | /* useful info found at http://www.a-netz.de/lcd.en.php |
| simon | 1:ac48b187213c | 27 | * |
| simon | 1:ac48b187213c | 28 | * Initialisation |
| simon | 1:ac48b187213c | 29 | * ============== |
| simon | 1:ac48b187213c | 30 | * |
| simon | 1:ac48b187213c | 31 | * After attaching the supply voltage/after a reset, the display needs to be brought in to a defined state |
| simon | 1:ac48b187213c | 32 | * |
| simon | 1:ac48b187213c | 33 | * - wait approximately 15 ms so the display is ready to execute commands |
| simon | 1:ac48b187213c | 34 | * - Execute the command 0x30 ("Display Settings") three times (wait 1,64ms after each command, the busy flag cannot be queried now). |
| simon | 1:ac48b187213c | 35 | * - The display is in 8 bit mode, so if you have only connected 4 data pins you should only transmit the higher nibble of each command. |
| simon | 1:ac48b187213c | 36 | * - If you want to use the 4 bit mode, now you can execute the command to switch over to this mode now. |
| simon | 1:ac48b187213c | 37 | * - Execute the "clear display" command |
| simon | 1:ac48b187213c | 38 | * |
| simon | 1:ac48b187213c | 39 | * Timing |
| simon | 1:ac48b187213c | 40 | * ====== |
| simon | 1:ac48b187213c | 41 | * |
| simon | 1:ac48b187213c | 42 | * Nearly all commands transmitted to the display need 40us for execution. |
| simon | 1:ac48b187213c | 43 | * Exceptions are the commands "Clear Display and Reset" and "Set Cursor to Start Position" |
| simon | 1:ac48b187213c | 44 | * These commands need 1.64ms for execution. These timings are valid for all displays working with an |
| simon | 1:ac48b187213c | 45 | * internal clock of 250kHz. But I do not know any displays that use other frequencies. Any time you |
| simon | 1:ac48b187213c | 46 | * can use the busy flag to test if the display is ready to accept the next command. |
| simon | 1:ac48b187213c | 47 | * |
| simon | 1:ac48b187213c | 48 | * _e is kept high apart from calling clock |
| simon | 1:ac48b187213c | 49 | * _rw is kept 0 (write) apart from actions that uyse it differently |
| simon | 1:ac48b187213c | 50 | * _rs is set by the data/command writes |
| simon | 1:ac48b187213c | 51 | */ |
| simon | 1:ac48b187213c | 52 | |
| simon | 1:ac48b187213c | 53 | TextLCD::TextLCD(PinName rs, PinName e, PinName d0, PinName d1, |
| simon | 1:ac48b187213c | 54 | PinName d2, PinName d3, LCDType type) : _rs(rs), |
| simon | 1:ac48b187213c | 55 | _e(e), _d(d0, d1, d2, d3), |
| simon | 1:ac48b187213c | 56 | _type(type) { |
| simon | 1:ac48b187213c | 57 | |
| simon | 1:ac48b187213c | 58 | _e = 1; |
| simon | 1:ac48b187213c | 59 | _rs = 0; // command mode |
| simon | 1:ac48b187213c | 60 | |
| simon | 1:ac48b187213c | 61 | wait(0.015); // Wait 15ms to ensure powered up |
| simon | 1:ac48b187213c | 62 | |
| simon | 1:ac48b187213c | 63 | // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus) |
| simon | 1:ac48b187213c | 64 | for (int i=0; i<3; i++) { |
| simon | 1:ac48b187213c | 65 | writeByte(0x3); |
| simon | 1:ac48b187213c | 66 | wait(0.00164); // this command takes 1.64ms, so wait for it |
| simon | 1:ac48b187213c | 67 | } |
| simon | 1:ac48b187213c | 68 | writeByte(0x2); // 4-bit mode |
| simon | 1:ac48b187213c | 69 | wait(0.000040f); // most instructions take 40us |
| simon | 1:ac48b187213c | 70 | |
| simon | 1:ac48b187213c | 71 | writeCommand(0x28); // Function set 001 BW N F - - |
| simon | 1:ac48b187213c | 72 | writeCommand(0x0C); |
| simon | 1:ac48b187213c | 73 | writeCommand(0x6); // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes |
| simon | 1:ac48b187213c | 74 | cls(); |
| simon | 1:ac48b187213c | 75 | } |
| simon | 1:ac48b187213c | 76 | |
| simon | 1:ac48b187213c | 77 | void TextLCD::character(int column, int row, int c) { |
| simon | 1:ac48b187213c | 78 | int a = address(column, row); |
| simon | 1:ac48b187213c | 79 | writeCommand(a); |
| simon | 1:ac48b187213c | 80 | writeData(c); |
| simon | 1:ac48b187213c | 81 | } |
| simon | 1:ac48b187213c | 82 | |
| simon | 1:ac48b187213c | 83 | void TextLCD::cls() { |
| simon | 1:ac48b187213c | 84 | writeCommand(0x01); // cls, and set cursor to 0 |
| simon | 1:ac48b187213c | 85 | wait(0.00164f); // This command takes 1.64 ms |
| simon | 1:ac48b187213c | 86 | locate(0, 0); |
| simon | 1:ac48b187213c | 87 | } |
| simon | 1:ac48b187213c | 88 | |
| simon | 1:ac48b187213c | 89 | void TextLCD::locate(int column, int row) { |
| simon | 1:ac48b187213c | 90 | _column = column; |
| simon | 1:ac48b187213c | 91 | _row = row; |
| simon | 1:ac48b187213c | 92 | } |
| simon | 1:ac48b187213c | 93 | |
| simon | 1:ac48b187213c | 94 | int TextLCD::_putc(int value) { |
| simon | 1:ac48b187213c | 95 | if (value == '\n') { |
| simon | 1:ac48b187213c | 96 | _column = 0; |
| simon | 1:ac48b187213c | 97 | _row++; |
| simon | 1:ac48b187213c | 98 | if (_row >= rows()) { |
| simon | 1:ac48b187213c | 99 | _row = 0; |
| simon | 1:ac48b187213c | 100 | } |
| simon | 1:ac48b187213c | 101 | } else { |
| simon | 1:ac48b187213c | 102 | character(_column, _row, value); |
| simon | 1:ac48b187213c | 103 | _column++; |
| simon | 1:ac48b187213c | 104 | if (_column >= columns()) { |
| simon | 1:ac48b187213c | 105 | _column = 0; |
| simon | 1:ac48b187213c | 106 | _row++; |
| simon | 1:ac48b187213c | 107 | if (_row >= rows()) { |
| simon | 1:ac48b187213c | 108 | _row = 0; |
| simon | 1:ac48b187213c | 109 | } |
| simon | 1:ac48b187213c | 110 | } |
| simon | 1:ac48b187213c | 111 | } |
| simon | 1:ac48b187213c | 112 | return value; |
| simon | 1:ac48b187213c | 113 | } |
| simon | 1:ac48b187213c | 114 | |
| simon | 1:ac48b187213c | 115 | int TextLCD::_getc() { |
| simon | 1:ac48b187213c | 116 | return -1; |
| simon | 1:ac48b187213c | 117 | } |
| simon | 1:ac48b187213c | 118 | |
| simon | 1:ac48b187213c | 119 | void TextLCD::writeByte(int value) { |
| simon | 1:ac48b187213c | 120 | _d = value >> 4; |
| simon | 1:ac48b187213c | 121 | wait(0.000040f); // most instructions take 40us |
| simon | 1:ac48b187213c | 122 | _e = 0; |
| simon | 1:ac48b187213c | 123 | wait(0.000040f); |
| simon | 1:ac48b187213c | 124 | _e = 1; |
| simon | 1:ac48b187213c | 125 | _d = value >> 0; |
| simon | 1:ac48b187213c | 126 | wait(0.000040f); |
| simon | 1:ac48b187213c | 127 | _e = 0; |
| simon | 1:ac48b187213c | 128 | wait(0.000040f); // most instructions take 40us |
| simon | 1:ac48b187213c | 129 | _e = 1; |
| simon | 1:ac48b187213c | 130 | } |
| simon | 1:ac48b187213c | 131 | |
| simon | 1:ac48b187213c | 132 | void TextLCD::writeCommand(int command) { |
| simon | 1:ac48b187213c | 133 | _rs = 0; |
| simon | 1:ac48b187213c | 134 | writeByte(command); |
| simon | 1:ac48b187213c | 135 | } |
| simon | 1:ac48b187213c | 136 | |
| simon | 1:ac48b187213c | 137 | void TextLCD::writeData(int data) { |
| simon | 1:ac48b187213c | 138 | _rs = 1; |
| simon | 1:ac48b187213c | 139 | writeByte(data); |
| simon | 1:ac48b187213c | 140 | } |
| simon | 1:ac48b187213c | 141 | |
| simon | 1:ac48b187213c | 142 | int TextLCD::address(int column, int row) { |
| simon | 1:ac48b187213c | 143 | switch (_type) { |
| simon | 1:ac48b187213c | 144 | case LCD20x4: |
| simon | 1:ac48b187213c | 145 | switch (row) { |
| simon | 1:ac48b187213c | 146 | case 0: |
| simon | 1:ac48b187213c | 147 | return 0x80 + column; |
| simon | 1:ac48b187213c | 148 | case 1: |
| simon | 1:ac48b187213c | 149 | return 0xc0 + column; |
| simon | 1:ac48b187213c | 150 | case 2: |
| simon | 1:ac48b187213c | 151 | return 0x94 + column; |
| simon | 1:ac48b187213c | 152 | case 3: |
| simon | 1:ac48b187213c | 153 | return 0xd4 + column; |
| simon | 1:ac48b187213c | 154 | } |
| simon | 1:ac48b187213c | 155 | case LCD16x2B: |
| simon | 1:ac48b187213c | 156 | return 0x80 + (row * 0x40) + column; |
| simon | 1:ac48b187213c | 157 | case LCD16x2: |
| simon | 1:ac48b187213c | 158 | case LCD20x2: |
| simon | 1:ac48b187213c | 159 | default: |
| simon | 1:ac48b187213c | 160 | return 0x80 + (row * 40) + column; |
| simon | 1:ac48b187213c | 161 | } |
| simon | 1:ac48b187213c | 162 | } |
| simon | 1:ac48b187213c | 163 | |
| simon | 1:ac48b187213c | 164 | int TextLCD::columns() { |
| simon | 1:ac48b187213c | 165 | switch (_type) { |
| simon | 1:ac48b187213c | 166 | case LCD20x4: |
| simon | 1:ac48b187213c | 167 | case LCD20x2: |
| simon | 1:ac48b187213c | 168 | return 20; |
| simon | 1:ac48b187213c | 169 | case LCD16x2: |
| simon | 1:ac48b187213c | 170 | case LCD16x2B: |
| simon | 1:ac48b187213c | 171 | default: |
| simon | 1:ac48b187213c | 172 | return 16; |
| simon | 1:ac48b187213c | 173 | } |
| simon | 1:ac48b187213c | 174 | } |
| simon | 1:ac48b187213c | 175 | |
| simon | 1:ac48b187213c | 176 | int TextLCD::rows() { |
| simon | 1:ac48b187213c | 177 | switch (_type) { |
| simon | 1:ac48b187213c | 178 | case LCD20x4: |
| simon | 1:ac48b187213c | 179 | return 4; |
| simon | 1:ac48b187213c | 180 | case LCD16x2: |
| simon | 1:ac48b187213c | 181 | case LCD16x2B: |
| simon | 1:ac48b187213c | 182 | case LCD20x2: |
| simon | 1:ac48b187213c | 183 | default: |
| simon | 1:ac48b187213c | 184 | return 2; |
| simon | 1:ac48b187213c | 185 | } |
| simon | 1:ac48b187213c | 186 | } |