TextLCD_20X4_Test - This is a modified version of TextLCD on the Cook…

Users » ym1784 » Code » TextLCD_20X4_Test

Yoshi Mimura / Mbed 2 deprecated TextLCD_20X4_Test

This is a modified version of TextLCD on the Cookbook for 20X4 LCD specific. This does not control RW line, so we can reduce the number of pin usage on the mbed.

Dependencies: mbed

TextLCD_20X4.cpp@0:f84245f91a5a, 2010-05-14 (annotated)

Committer:: ym1784
Date:: Fri May 14 21:19:39 2010 +0000
Revision:: 0:f84245f91a5a

Who changed what in which revision?

User	Revision	Line number	New contents of line
ym1784	0:f84245f91a5a	1	/* mbed TextLCD Library
ym1784	0:f84245f91a5a	2	* Copyright (c) 2007-2009 sford
ym1784	0:f84245f91a5a	3	* Released under the MIT License: http://mbed.org/license/mit
ym1784	0:f84245f91a5a	4	*
ym1784	0:f84245f91a5a	5	* TODO: Needs serious rework/neatening up!
ym1784	0:f84245f91a5a	6	*/
ym1784	0:f84245f91a5a	7
ym1784	0:f84245f91a5a	8	/*
ym1784	0:f84245f91a5a	9	* 2010/05/14 modified for 20X4 LCD by ym1784
ym1784	0:f84245f91a5a	10	*/
ym1784	0:f84245f91a5a	11
ym1784	0:f84245f91a5a	12	#include "TextLCD_20X4.h"
ym1784	0:f84245f91a5a	13
ym1784	0:f84245f91a5a	14	#include "mbed.h"
ym1784	0:f84245f91a5a	15	#include "error.h"
ym1784	0:f84245f91a5a	16
ym1784	0:f84245f91a5a	17	using namespace mbed;
ym1784	0:f84245f91a5a	18
ym1784	0:f84245f91a5a	19	/*
ym1784	0:f84245f91a5a	20	* useful info found at http://www.a-netz.de/lcd.en.php
ym1784	0:f84245f91a5a	21	*
ym1784	0:f84245f91a5a	22	*
ym1784	0:f84245f91a5a	23	* Initialization
ym1784	0:f84245f91a5a	24	* ==============
ym1784	0:f84245f91a5a	25	*
ym1784	0:f84245f91a5a	26	* After attaching the supply voltage/after a reset, the display needs to be brought in to a defined state
ym1784	0:f84245f91a5a	27	*
ym1784	0:f84245f91a5a	28	* - wait approximately 15 ms so the display is ready to execute commands
ym1784	0:f84245f91a5a	29	* - Execute the command 0x30 ("Display Settings") three times (wait 1,64ms after each command, the busy flag cannot be queried now).
ym1784	0:f84245f91a5a	30	* - 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.
ym1784	0:f84245f91a5a	31	* - If you want to use the 4 bit mode, now you can execute the command to switch over to this mode now.
ym1784	0:f84245f91a5a	32	* - Execute the "clear display" command
ym1784	0:f84245f91a5a	33	*
ym1784	0:f84245f91a5a	34	* Timing
ym1784	0:f84245f91a5a	35	* ======
ym1784	0:f84245f91a5a	36	*
ym1784	0:f84245f91a5a	37	* Nearly all commands transmitted to the display need 40us for execution.
ym1784	0:f84245f91a5a	38	* Exceptions are the commands "Clear Display and Reset" and "Set Cursor to Start Position"
ym1784	0:f84245f91a5a	39	* These commands need 1.64ms for execution. These timings are valid for all displays working with an
ym1784	0:f84245f91a5a	40	* internal clock of 250kHz. But I do not know any displays that use other frequencies. Any time you
ym1784	0:f84245f91a5a	41	* can use the busy flag to test if the display is ready to accept the next command.
ym1784	0:f84245f91a5a	42	*
ym1784	0:f84245f91a5a	43	* _e is kept high apart from calling clock
ym1784	0:f84245f91a5a	44	* _rw is kept 0 (write) apart from actions that uyse it differently
ym1784	0:f84245f91a5a	45	* -> on this program, the _rw is not used ... ym1784
ym1784	0:f84245f91a5a	46	* _rs is set by the data/command writes
ym1784	0:f84245f91a5a	47	*/
ym1784	0:f84245f91a5a	48
ym1784	0:f84245f91a5a	49	TextLCD_20X4::TextLCD_20X4(PinName rs, PinName e, PinName d0, PinName d1,
ym1784	0:f84245f91a5a	50	PinName d2, PinName d3, int columns, int rows) : _rs(rs), _e(e), _d(d0, d1, d2, d3),
ym1784	0:f84245f91a5a	51	_columns(columns), _rows(rows) {
ym1784	0:f84245f91a5a	52
ym1784	0:f84245f91a5a	53	_rows = 4;
ym1784	0:f84245f91a5a	54	_columns = 20;
ym1784	0:f84245f91a5a	55	// Mon, 27 Apr 2009 23:32:34 +0200
ym1784	0:f84245f91a5a	56	// Kevin Konradt:
ym1784	0:f84245f91a5a	57	// When using a LCD with 1 row x 16 characters
ym1784	0:f84245f91a5a	58	// instead of 2x16, try changing _columns to 8.
ym1784	0:f84245f91a5a	59	// (display seems to split the 16 characters into
ym1784	0:f84245f91a5a	60	// 2 virtual rows with 8 characters each.)
ym1784	0:f84245f91a5a	61	//
ym1784	0:f84245f91a5a	62	// 2010/05/14 ym1784
ym1784	0:f84245f91a5a	63	// This program is only for 4 rows x 20 characters specific
ym1784	0:f84245f91a5a	64
ym1784	0:f84245f91a5a	65	// _rw = 0; // on this program, the _rw is not used ... ym1784
ym1784	0:f84245f91a5a	66	_e = 1;
ym1784	0:f84245f91a5a	67	_rs = 0; // command mode
ym1784	0:f84245f91a5a	68
ym1784	0:f84245f91a5a	69	// Should theoretically wait 15ms, but most things will be powered up pre-reset
ym1784	0:f84245f91a5a	70	// so i'll disable that for the minute. If implemented, could wait 15ms post reset
ym1784	0:f84245f91a5a	71	// instead
ym1784	0:f84245f91a5a	72	wait(0.015); // for safety ... ym1784
ym1784	0:f84245f91a5a	73
ym1784	0:f84245f91a5a	74	// send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
ym1784	0:f84245f91a5a	75	for(int i=0; i<3; i++) {
ym1784	0:f84245f91a5a	76	writeNibble(0x3);
ym1784	0:f84245f91a5a	77	wait(0.00164); // this command takes 1.64ms, so wait for it
ym1784	0:f84245f91a5a	78	}
ym1784	0:f84245f91a5a	79	writeNibble(0x2); // 4-bit mode
ym1784	0:f84245f91a5a	80
ym1784	0:f84245f91a5a	81	writeCommand(0x28); // Function set 001 BW N F - -
ym1784	0:f84245f91a5a	82	writeCommand(0x0C);
ym1784	0:f84245f91a5a	83	writeCommand(0x6); // Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
ym1784	0:f84245f91a5a	84
ym1784	0:f84245f91a5a	85	cls();
ym1784	0:f84245f91a5a	86	}
ym1784	0:f84245f91a5a	87
ym1784	0:f84245f91a5a	88	int TextLCD_20X4::_putc(int value) {
ym1784	0:f84245f91a5a	89	if(value == '\n') {
ym1784	0:f84245f91a5a	90	newline();
ym1784	0:f84245f91a5a	91	} else {
ym1784	0:f84245f91a5a	92	writeData(value);
ym1784	0:f84245f91a5a	93	}
ym1784	0:f84245f91a5a	94	return value;
ym1784	0:f84245f91a5a	95	}
ym1784	0:f84245f91a5a	96
ym1784	0:f84245f91a5a	97	int TextLCD_20X4::_getc() {
ym1784	0:f84245f91a5a	98	return 0;
ym1784	0:f84245f91a5a	99	}
ym1784	0:f84245f91a5a	100
ym1784	0:f84245f91a5a	101	void TextLCD_20X4::newline() {
ym1784	0:f84245f91a5a	102	_column = 0;
ym1784	0:f84245f91a5a	103	_row++;
ym1784	0:f84245f91a5a	104	if(_row >= _rows) {
ym1784	0:f84245f91a5a	105	_row = 0;
ym1784	0:f84245f91a5a	106	}
ym1784	0:f84245f91a5a	107	locate(_column, _row);
ym1784	0:f84245f91a5a	108	}
ym1784	0:f84245f91a5a	109
ym1784	0:f84245f91a5a	110	void TextLCD_20X4::locate(int column, int row) {
ym1784	0:f84245f91a5a	111	if(column < 0 \|\| column >= _columns \|\| row < 0 \|\| row >= _rows) {
ym1784	0:f84245f91a5a	112	error("locate(%d,%d) out of range on %dx%d display", column, row, _columns, _rows);
ym1784	0:f84245f91a5a	113	return;
ym1784	0:f84245f91a5a	114	}
ym1784	0:f84245f91a5a	115	_row = row;
ym1784	0:f84245f91a5a	116	_column = column;
ym1784	0:f84245f91a5a	117	// modified for 20X4 LCD
ym1784	0:f84245f91a5a	118	switch (_row) {
ym1784	0:f84245f91a5a	119	case (0) : address = 0x80 + _column;
ym1784	0:f84245f91a5a	120	break;
ym1784	0:f84245f91a5a	121	case (1) : address = 0xc0 + _column;
ym1784	0:f84245f91a5a	122	break;
ym1784	0:f84245f91a5a	123	case (2) : address = 0x94 + _column;
ym1784	0:f84245f91a5a	124	break;
ym1784	0:f84245f91a5a	125	case (3) : address = 0xd4 + _column;
ym1784	0:f84245f91a5a	126	break;
ym1784	0:f84245f91a5a	127	} // switch
ym1784	0:f84245f91a5a	128	writeCommand(address);
ym1784	0:f84245f91a5a	129	}
ym1784	0:f84245f91a5a	130
ym1784	0:f84245f91a5a	131	void TextLCD_20X4::cls() {
ym1784	0:f84245f91a5a	132	writeCommand(0x01); // Clear Display
ym1784	0:f84245f91a5a	133	wait(0.00164f); // This command takes 1.64 ms
ym1784	0:f84245f91a5a	134	// locate(0, 0); // We don't have to do this here
ym1784	0:f84245f91a5a	135	}
ym1784	0:f84245f91a5a	136
ym1784	0:f84245f91a5a	137	void TextLCD_20X4::reset() {
ym1784	0:f84245f91a5a	138	cls();
ym1784	0:f84245f91a5a	139	}
ym1784	0:f84245f91a5a	140
ym1784	0:f84245f91a5a	141	void TextLCD_20X4::clock() {
ym1784	0:f84245f91a5a	142	wait(0.000040f);
ym1784	0:f84245f91a5a	143	_e = 0;
ym1784	0:f84245f91a5a	144	wait(0.000040f); // most instructions take 40us
ym1784	0:f84245f91a5a	145	_e = 1;
ym1784	0:f84245f91a5a	146	}
ym1784	0:f84245f91a5a	147
ym1784	0:f84245f91a5a	148	void TextLCD_20X4::writeNibble(int value) {
ym1784	0:f84245f91a5a	149	_d = value;
ym1784	0:f84245f91a5a	150	clock();
ym1784	0:f84245f91a5a	151	}
ym1784	0:f84245f91a5a	152
ym1784	0:f84245f91a5a	153	void TextLCD_20X4::writeByte(int value) {
ym1784	0:f84245f91a5a	154	writeNibble(value >> 4);
ym1784	0:f84245f91a5a	155	writeNibble(value >> 0);
ym1784	0:f84245f91a5a	156	}
ym1784	0:f84245f91a5a	157
ym1784	0:f84245f91a5a	158	void TextLCD_20X4::writeCommand(int command) {
ym1784	0:f84245f91a5a	159	_rs = 0;
ym1784	0:f84245f91a5a	160	writeByte(command);
ym1784	0:f84245f91a5a	161	}
ym1784	0:f84245f91a5a	162
ym1784	0:f84245f91a5a	163	void TextLCD_20X4::writeData(int data) {
ym1784	0:f84245f91a5a	164	_rs = 1;
ym1784	0:f84245f91a5a	165	writeByte(data);
ym1784	0:f84245f91a5a	166	_column++;
ym1784	0:f84245f91a5a	167	if(_column >= _columns) {
ym1784	0:f84245f91a5a	168	newline();
ym1784	0:f84245f91a5a	169	}
ym1784	0:f84245f91a5a	170	}

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	14 May 2010
Imports:	242
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	1
Followers:	5

TextLCD_20X4.cpp@0:f84245f91a5a, 2010-05-14 (annotated)

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