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Pi4J Java Examples using the Pi4J Library
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/*
 * #%L
 * **********************************************************************
 * ORGANIZATION  :  Pi4J
 * PROJECT       :  Pi4J :: Java Examples
 * FILENAME      :  SerialBufferedDataExample.java
 *
 * This file is part of the Pi4J project. More information about
 * this project can be found here:  https://pi4j.com/
 * **********************************************************************
 * %%
 * Copyright (C) 2012 - 2021 Pi4J
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */

import com.pi4j.io.serial.*;
import com.pi4j.util.CommandArgumentParser;
import com.pi4j.util.Console;
import com.pi4j.util.StringUtil;

import java.io.IOException;

/**
 * This example code demonstrates how to perform serial communications using the Raspberry Pi.
 * This example configures Pi4J to buffer received data in memory and will print the received data
 * out via the console every ten seconds.
 *
 * @author Robert Savage
 */
public class SerialBufferedDataExample {

    /**
     * This example program supports the following optional command arguments/options:
     *   "--device (device-path)"                   [DEFAULT: /dev/ttyAMA0]
     *   "--baud (baud-rate)"                       [DEFAULT: 38400]
     *   "--data-bits (5|6|7|8)"                    [DEFAULT: 8]
     *   "--parity (none|odd|even)"                 [DEFAULT: none]
     *   "--stop-bits (1|2)"                        [DEFAULT: 1]
     *   "--flow-control (none|hardware|software)"  [DEFAULT: none]
     *
     * @param args
     * @throws InterruptedException
     * @throws IOException
     */
    public static void main(String args[]) throws InterruptedException, IOException {

        // !! ATTENTION !!
        // By default, the serial port is configured as a console port
        // for interacting with the Linux OS shell.  If you want to use
        // the serial port in a software program, you must disable the
        // OS from using this port.
        //
        // Please see this blog article for instructions on how to disable
        // the OS console for this port:
        // https://www.cube-controls.com/2015/11/02/disable-serial-port-terminal-output-on-raspbian/

        // create Pi4J console wrapper/helper
        // (This is a utility class to abstract some of the boilerplate code)
        final Console console = new Console();

        // print program title/header
        console.title("<-- The Pi4J Project -->", "Serial Buffered Data Example");

        // allow for user to exit program using CTRL-C
        console.promptForExit();

        // create an instance of the serial communications class
        final Serial serial = SerialFactory.createInstance();

        // enable receive data buffer
        serial.setBufferingDataReceived(true);

        try {
            // create serial config object
            SerialConfig config = new SerialConfig();

            // set default serial settings (device, baud rate, flow control, etc)
            //
            // by default, use the DEFAULT com port on the Raspberry Pi (exposed on GPIO header)
            // NOTE: this utility method will determine the default serial port for the
            //       detected platform and board/model.  For all Raspberry Pi models
            //       except the 3B, it will return "/dev/ttyAMA0".  For Raspberry Pi
            //       model 3B may return "/dev/ttyS0" or "/dev/ttyAMA0" depending on
            //       environment configuration.
            config.device(SerialPort.getDefaultPort())
                  .baud(Baud._38400)
                  .dataBits(DataBits._8)
                  .parity(Parity.NONE)
                  .stopBits(StopBits._1)
                  .flowControl(FlowControl.NONE);

            // parse optional command argument options to override the default serial settings.
            if(args.length > 0){
                config = CommandArgumentParser.getSerialConfig(config, args);
            }

            // display connection details
            console.box(" Connecting to: " + config.toString(),
                    " Data received on serial port will be displayed below every ten seconds.");

            // open the default serial device/port with the configuration settings
            serial.open(config);

            // continuous loop to keep the program running until the user terminates the program
            while(console.isRunning()) {
                try {
                    // wait 10 seconds before reading data;
                    // any serial data will be buffered inside Pi4J serial data receive buffer
                    Thread.sleep(10000);

                    // if any data is available in the serial receive buffer, then read it now
                    int available = serial.available();
                    if(available > 0) {
                        byte[] data = serial.read();
                        System.out.print("[" + available + " BYTES AVAILABLE] : ");
                        System.out.println(StringUtil.byteArrayToHex(data));
                    } else {
                        System.out.println("[NO DATA AVAILABLE]");
                    }
                }
                catch(Exception ex){
                    ex.printStackTrace();
                }
            }

            // we are done; close serial port
            serial.close();
        }
        catch(IOException ex) {
            console.println(" ==>> SERIAL SETUP FAILED : " + ex.getMessage());
            return;
        }
    }
}