TextLCD - TextLCD library for controlling various LCD panel…

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TextLCD library for controlling various LCD panels based on the HD44780 4-bit interface

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	}

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Type:	Library
Created:	21 Jun 2020
Imports:	6
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TextLCD.cpp@1:ac48b187213c, 2010-05-27 (annotated)

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