com.pi4j.wiringpi.Lcd Maven / Gradle / Ivy
package com.pi4j.wiringpi;
/*
* #%L
* **********************************************************************
ORGANIZATION : Pi4J
PROJECT : Pi4J :: Java Library (Core)
FILENAME : Lcd.java
This file is part of the Pi4J project. More information about
this project can be found here: http://www.pi4j.com/
**********************************************************************
* %%
* Copyright (C) 2012 - 2018 Pi4J
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import com.pi4j.util.NativeLibraryLoader;
/**
*
* Part of wiringPi is a library to allow access to parallel interface LCD displays (Those that use
* the popular Hitachi HD44780U or compatible controllers)
*
*
*
* The library is simple to use in your own programs, however wiring the displays up may be
* challenging, so do take care. It is possible to wire up more than one display! In 8-bit mode, the
* first display needs 10 GPIO pins and each additional display needs just one more pin, so with a
* maximum of 17 GPIO pins, that's 8 displays. If you move to using a 4-bit interface (trivial in
* the code), then it's 4 more displays and 12 LCDs! However I suspect the rest of the wiring might be
* somewhat challenging. Wiring is described at the end of the this page.
*
*
*
* The LCD display can be either a 5V display or a 3,3v display, however if we are using a 5V
* display then we must make absolutely sure the display can never write data back to the Raspberry
* Pi, otherwise it will present 5V on the Pi's GPIO pins which will not be good. At best you'll
* destroy the pin drivers, at worst you'll destroy your Pi.
*
*
*
* So make sure you always connect the R/W pin on the display to ground to force the display to be
* read-only to the host.
*
*
*
* Before using the Pi4J library, you need to ensure that the Java VM in configured with access to
* the following system libraries:
*
* - pi4j
* - wiringPi
*
* This library depends on the wiringPi native system library. (developed by
* Gordon Henderson @ http://wiringpi.com/)
*
*
*
* @see http://www.pi4j.com/
* @see http://wiringpi.com/dev-lib/lcd-library/
* @author Robert Savage (http://www.savagehomeautomation.com)
*/
public class Lcd {
// private constructor
private Lcd() {
// forbid object construction
}
static {
// Load the platform library
NativeLibraryLoader.load("libpi4j.so");
}
/**
*
* First, you need to initialize wiringPi in the way you want to. The LCD library will call
* pinMode functions, but these are ignored if you have already set the modes using the gpio
* program and want to use the wiringPiSetupSys() mechanism.
*
*
*
* int lcdInit(int rows, int cols, int bits, int rs, int strb, int d0, int d1, int d2, int d3, int d4,
* int d5, int d6, int d7);
*
*
*
* This is the main initialization function and must be called before you use any other LCD
* functions.
*
*
*
* Rows and cols are the rows and columns on the display (e.g. 2, 16 or 4,20). Bits is the
* number of bits wide on the interface (4 or 8). The rs and strb represent the pin numbers of
* the displays RS pin and Strobe (E) pin. The parameters d0 through d7 are the pin numbers of
* the 8 data pins connected from the Pi to the display. Only the first 4 are used if you are
* running the display in 4-bit mode.
*
*
*
* The pin numbers will be either wiringPi pin numbers of GPIO pin numbers depending on which
* wiringPiSetup function you used.
*
*
*
* The return value is the handle to be used for all subsequent calls to the lcd library when
* dealing with that LCD, or -1 to indicate a fault. (Usually incorrect parameters)
*
*
* @see http://wiringpi.com/dev-lib/lcd-library
*
* @param rows number of rows
* @param cols number of columns
* @param bits number of bits wide on the interface (4 or 8)
* @param rs pin number of the RS pin
* @param strb pin number of the strobe (E) pin
* @param d0 pin number for driving bit 1
* @param d1 pin number for driving bit 2
* @param d2 pin number for driving bit 3
* @param d3 pin number for driving bit 4
* @param d4 pin number for driving bit 5 (only used in 8-bit mode)
* @param d5 pin number for driving bit 6 (only used in 8-bit mode)
* @param d6 pin number for driving bit 7 (only used in 8-bit mode)
* @param d7 pin number for driving bit 8 (only used in 8-bit mode)
* @return The return value is the �handle� to be used for all subsequent calls to the lcd library when dealing with that LCD, or -1 to indicate a fault. (Usually incorrect parameters)
*/
public static native int lcdInit(int rows, int cols, int bits, int rs, int strb, int d0,
int d1, int d2, int d3, int d4, int d5, int d6, int d7);
/**
*
* Set the cursor to the home position.
*
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
*/
public static native void lcdHome(int handle);
/**
*
* Clears the LCD screen.
*
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
*/
public static native void lcdClear(int handle);
/**
*
* Turns the LCD display ON (1) / OFF (0)
*
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
*/
public static native void lcdDisplay(int handle, int state);
/**
*
* Turns the LCD cursor ON (1) / OFF (0)
*
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
*/
public static native void lcdCursor(int handle, int state);
/**
*
* Turns the LCD cursor blinking behavior ON (1) / OFF (0)
*
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
*/
public static native void lcdCursorBlink(int handle, int state);
/**
*
* Set the position of the cursor for subsequent text entry.
*
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
* @param x column position staring at 0 (left)
* @param y row position starting at 0 (top)
*/
public static native void lcdPosition(int handle, int x, int y);
/**
*
* This allows you to re-define one of the 8 user-definable chanracters in the display. The data array is 8 bytes
* which represent the character from the top-line to the bottom line. Note that the characters are actually 5�8,
* so only the lower 5 bits are used. The index is from 0 to 7 and you can subsequently print the character defined
* using the lcdPutchar() call.
*
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
* @param index index value from 0 to 7
* @param data 8 bytes which represent the character from the top-line to the bottom line
*/
public static native void lcdCharDef(int handle, int index, byte data[]);
/**
*
* Write a single character of data to the LCD display.
*
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
* @param data character data to write
*/
public static native void lcdPutchar(int handle, byte data);
/**
* Write string of data to the LCD display.
*
* (ATTENTION: the 'data' argument can only be a maximum of 512 characters.)
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
* @param data string data to write
*/
public static native void lcdPuts(int handle, String data);
/**
* Write formatted string of data to the LCD display.
*
* (ATTENTION: the 'data' argument can only be a maximum of 512 characters.)
*
* @see http://wiringpi.com/dev-lib/lcd-library/
* @param handle file handle
* @param data format string to write
* @param args string arguments to use in formatted string
*/
public static void lcdPuts(int handle, String data, String... args) {
lcdPuts(handle, String.format(data, (Object[]) args));
}
}