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LCD I2C
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TextLCD.cpp@0:edfb85c53631, 2010-05-22 (annotated)
- Committer:
- simon
- Date:
- Sat May 22 18:18:19 2010 +0000
- Revision:
- 0:edfb85c53631
- Child:
- 1:ac48b187213c
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| simon | 0:edfb85c53631 | 1 | /* mbed TextLCD Library, 4-bit 2x16 |
| simon | 0:edfb85c53631 | 2 | * Copyright (c) 2007-2010, sford |
| simon | 0:edfb85c53631 | 3 | * |
| simon | 0:edfb85c53631 | 4 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| simon | 0:edfb85c53631 | 5 | * of this software and associated documentation files (the "Software"), to deal |
| simon | 0:edfb85c53631 | 6 | * in the Software without restriction, including without limitation the rights |
| simon | 0:edfb85c53631 | 7 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| simon | 0:edfb85c53631 | 8 | * copies of the Software, and to permit persons to whom the Software is |
| simon | 0:edfb85c53631 | 9 | * furnished to do so, subject to the following conditions: |
| simon | 0:edfb85c53631 | 10 | * |
| simon | 0:edfb85c53631 | 11 | * The above copyright notice and this permission notice shall be included in |
| simon | 0:edfb85c53631 | 12 | * all copies or substantial portions of the Software. |
| simon | 0:edfb85c53631 | 13 | * |
| simon | 0:edfb85c53631 | 14 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| simon | 0:edfb85c53631 | 15 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| simon | 0:edfb85c53631 | 16 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| simon | 0:edfb85c53631 | 17 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| simon | 0:edfb85c53631 | 18 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| simon | 0:edfb85c53631 | 19 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| simon | 0:edfb85c53631 | 20 | * THE SOFTWARE. |
| simon | 0:edfb85c53631 | 21 | */ |
| simon | 0:edfb85c53631 | 22 | |
| simon | 0:edfb85c53631 | 23 | #include "TextLCD.h" |
| simon | 0:edfb85c53631 | 24 | #include "mbed.h" |
| simon | 0:edfb85c53631 | 25 | |
| simon | 0:edfb85c53631 | 26 | /* |
| simon | 0:edfb85c53631 | 27 | * useful info found at http://www.a-netz.de/lcd.en.php |
| simon | 0:edfb85c53631 | 28 | * |
| simon | 0:edfb85c53631 | 29 | * Initialisation |
| simon | 0:edfb85c53631 | 30 | * ============== |
| simon | 0:edfb85c53631 | 31 | * |
| simon | 0:edfb85c53631 | 32 | * After attaching the supply voltage/after a reset, the display needs to be brought in to a defined state |
| simon | 0:edfb85c53631 | 33 | * |
| simon | 0:edfb85c53631 | 34 | * - wait approximately 15 ms so the display is ready to execute commands |
| simon | 0:edfb85c53631 | 35 | * - Execute the command 0x30 ("Display Settings") three times (wait 1,64ms after each command, the busy flag cannot be queried now). |
| simon | 0:edfb85c53631 | 36 | * - 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 | 0:edfb85c53631 | 37 | * - If you want to use the 4 bit mode, now you can execute the command to switch over to this mode now. |
| simon | 0:edfb85c53631 | 38 | * - Execute the "clear display" command |
| simon | 0:edfb85c53631 | 39 | * |
| simon | 0:edfb85c53631 | 40 | * Timing |
| simon | 0:edfb85c53631 | 41 | * ====== |
| simon | 0:edfb85c53631 | 42 | * |
| simon | 0:edfb85c53631 | 43 | * Nearly all commands transmitted to the display need 40us for execution. |
| simon | 0:edfb85c53631 | 44 | * Exceptions are the commands "Clear Display and Reset" and "Set Cursor to Start Position" |
| simon | 0:edfb85c53631 | 45 | * These commands need 1.64ms for execution. These timings are valid for all displays working with an |
| simon | 0:edfb85c53631 | 46 | * internal clock of 250kHz. But I do not know any displays that use other frequencies. Any time you |
| simon | 0:edfb85c53631 | 47 | * can use the busy flag to test if the display is ready to accept the next command. |
| simon | 0:edfb85c53631 | 48 | * |
| simon | 0:edfb85c53631 | 49 | * _e is kept high apart from calling clock |
| simon | 0:edfb85c53631 | 50 | * _rw is kept 0 (write) apart from actions that uyse it differently |
| simon | 0:edfb85c53631 | 51 | * _rs is set by the data/command writes |
| simon | 0:edfb85c53631 | 52 | */ |
| simon | 0:edfb85c53631 | 53 | |
| simon | 0:edfb85c53631 | 54 | TextLCD::TextLCD(PinName rs, PinName rw, PinName e, PinName d0, PinName d1, |
| simon | 0:edfb85c53631 | 55 | PinName d2, PinName d3) : _rw(rw), _rs(rs), |
| simon | 0:edfb85c53631 | 56 | _e(e), _d(d0, d1, d2, d3) { |
| simon | 0:edfb85c53631 | 57 | |
| simon | 0:edfb85c53631 | 58 | _rw = 0; |
| simon | 0:edfb85c53631 | 59 | _e = 1; |
| simon | 0:edfb85c53631 | 60 | _rs = 0; // command mode |
| simon | 0:edfb85c53631 | 61 | |
| simon | 0:edfb85c53631 | 62 | // Should theoretically wait 15ms, but most things will be powered up pre-reset |
| simon | 0:edfb85c53631 | 63 | // so i'll disable that for the minute. If implemented, could wait 15ms post reset |
| simon | 0:edfb85c53631 | 64 | // instead |
| simon | 0:edfb85c53631 | 65 | // wait(0.015); |
| simon | 0:edfb85c53631 | 66 | |
| simon | 0:edfb85c53631 | 67 | // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus) |
| simon | 0:edfb85c53631 | 68 | for(int i=0; i<3; i++) { |
| simon | 0:edfb85c53631 | 69 | writeByte(0x3); |
| simon | 0:edfb85c53631 | 70 | wait(0.00164); // this command takes 1.64ms, so wait for it |
| simon | 0:edfb85c53631 | 71 | } |
| simon | 0:edfb85c53631 | 72 | writeByte(0x2); // 4-bit mode |
| simon | 0:edfb85c53631 | 73 | |
| simon | 0:edfb85c53631 | 74 | writeCommand(0x28); // Function set 001 BW N F - - |
| simon | 0:edfb85c53631 | 75 | writeCommand(0x0C); |
| simon | 0:edfb85c53631 | 76 | writeCommand(0x6); // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes |
| simon | 0:edfb85c53631 | 77 | cls(); |
| simon | 0:edfb85c53631 | 78 | } |
| simon | 0:edfb85c53631 | 79 | |
| simon | 0:edfb85c53631 | 80 | void TextLCD::character(int column, int row, int c) { |
| simon | 0:edfb85c53631 | 81 | int address = 0x80 + (row * 40) + column; // memory starts at 0x80, and is 40 chars long per row |
| simon | 0:edfb85c53631 | 82 | writeCommand(address); |
| simon | 0:edfb85c53631 | 83 | writeData(c); |
| simon | 0:edfb85c53631 | 84 | } |
| simon | 0:edfb85c53631 | 85 | |
| simon | 0:edfb85c53631 | 86 | int TextLCD::columns() { |
| simon | 0:edfb85c53631 | 87 | return 16; |
| simon | 0:edfb85c53631 | 88 | } |
| simon | 0:edfb85c53631 | 89 | |
| simon | 0:edfb85c53631 | 90 | int TextLCD::rows() { |
| simon | 0:edfb85c53631 | 91 | return 2; |
| simon | 0:edfb85c53631 | 92 | } |
| simon | 0:edfb85c53631 | 93 | |
| simon | 0:edfb85c53631 | 94 | void TextLCD::writeByte(int value) { |
| simon | 0:edfb85c53631 | 95 | _d = value >> 4; |
| simon | 0:edfb85c53631 | 96 | wait(0.000040f); // most instructions take 40us |
| simon | 0:edfb85c53631 | 97 | _e = 0; |
| simon | 0:edfb85c53631 | 98 | wait(0.000040f); |
| simon | 0:edfb85c53631 | 99 | _e = 1; |
| simon | 0:edfb85c53631 | 100 | _d = value >> 0; |
| simon | 0:edfb85c53631 | 101 | wait(0.000040f); |
| simon | 0:edfb85c53631 | 102 | _e = 0; |
| simon | 0:edfb85c53631 | 103 | wait(0.000040f); // most instructions take 40us |
| simon | 0:edfb85c53631 | 104 | _e = 1; |
| simon | 0:edfb85c53631 | 105 | } |
| simon | 0:edfb85c53631 | 106 | |
| simon | 0:edfb85c53631 | 107 | void TextLCD::writeCommand(int command) { |
| simon | 0:edfb85c53631 | 108 | _rs = 0; |
| simon | 0:edfb85c53631 | 109 | writeByte(command); |
| simon | 0:edfb85c53631 | 110 | } |
| simon | 0:edfb85c53631 | 111 | |
| simon | 0:edfb85c53631 | 112 | void TextLCD::writeData(int data) { |
| simon | 0:edfb85c53631 | 113 | _rs = 1; |
| simon | 0:edfb85c53631 | 114 | writeByte(data); |
| simon | 0:edfb85c53631 | 115 | } |