Enable and demonstrate how to use /dev/hidraw

src/main/java/gnu/io/RXTXCommDriver.java

@@ -655,6 +655,7 @@ else if ( osName.equals("Solaris") || osName.equals("SunOS"))
 						"ttyUSB", // for USB frobs
 						"ttyAMA", // Raspberry Pi
 						"rfcomm",       // bluetooth serial device
+						"hidraw",
 						"ttyircomm", // linux IrCommdevices (IrDA serial emu)
 						"ttyACM",// linux CDC ACM devices
 						"DyIO",// NRDyIO
@@ -677,6 +678,7 @@ else if(osName.equals("Linux-all-ports"))
 						"holter",    // custom card for heart monitoring
 						"modem",     // linux symbolic link to modem.
 						"rfcomm",       // bluetooth serial device
+						"hidraw",
 						"ttyircomm", // linux IrCommdevices (IrDA serial emu)
 						"ttycosa0c", // linux COSA/SRP synchronous serial card
 						"ttycosa1c", // linux COSA/SRP synchronous serial card

test/src/test/mpp/CRCUtil.java

@@ -0,0 +1,90 @@
+package test.mpp;
+// adapted from https://github.com/synogen/mpp/blob/master/src/main/java/org/mppsolartest/serial/CRCUtil.java
+
+public class CRCUtil {
+	private static final char[] crc_tb = new char[] { '\u0000', 'အ', '⁂', 'っ', '䂄', '傥', '惆', '烧', '脈', '鄩', 'ꅊ', '녫',
+		'소', '톭', '\ue1ce', '\uf1ef', 'ሱ', 'Ȑ', '㉳', '≒', '劵', '䊔', '狷', '拖', '錹', '茘', '덻', 'ꍚ', '펽', '쎜',
+		'\uf3ff', '\ue3de', '③', '㑃', 'Р', 'ᐁ', '擦', '瓇', '䒤', '咅', 'ꕪ', '땋', '蔨', '锉', '\ue5ee', '\uf5cf', '얬',
+		'햍', '㙓', '♲', 'ᘑ', 'ذ', '盗', '曶', '嚕', '䚴', '띛', 'ꝺ', '霙', '蜸', '\uf7df', '\ue7fe', '힝', '잼', '䣄', '壥',
+		'梆', '碧', 'ࡀ', 'ᡡ', '⠂', '㠣', '짌', '\ud9ed', '\ue98e', '羚', '襈', '饩', 'ꤊ', '뤫', '嫵', '䫔', '窷', '檖', 'ᩱ',
+		'\u0a50', '㨳', '⨒', '\udbfd', '쯜', '﮿', '\ueb9e', '魹', '識', '묻', '\uab1a', '沦', '粇', '䳤', '峅', 'Ⱒ', '㰃',
+		'ౠ', '᱁', '\uedae', 'ﶏ', '췬', '\uddcd', '괪', '봋', '赨', '鵉', '纗', '溶', '廕', '仴', '㸓', '⸲', 'ṑ', '\u0e70',
+		'ﾟ', '\uefbe', '\udfdd', '쿼', '뼛', '꼺', '齙', '轸', '醈', '膩', '뇊', 'ꇫ', '턌', '섭', '\uf14e', '\ue16f', 'ႀ',
+		'¡', 'ヂ', '⃣', '倄', '䀥', '灆', '恧', '莹', '鎘', 'ꏻ', '돚', '쌽', '팜', '\ue37f', '\uf35e', 'ʱ', 'ነ', '⋳', '㋒',
+		'䈵', '刔', '扷', '牖', '뗪', 'ꗋ', '閨', '薉', '\uf56e', '\ue54f', '픬', '씍', '㓢', 'Ⓝ', 'ᒠ', 'ҁ', '瑦', '摇', '吤',
+		'䐅', '\ua7db', '럺', '螙', '鞸', '\ue75f', '\uf77e', '윝', '휼', '⛓', '㛲', 'ڑ', 'ᚰ', '晗', '癶', '䘕', '嘴',
+		'\ud94c', '쥭', '癩', '\ue92f', '駈', '觩', '릊', 'ꦫ', '塄', '䡥', '砆', '栧', 'ᣀ', '࣡', '㢂', '⢣', '쭽', '\udb5c',
+		'\ueb3f', 'ﬞ', '诹', '鯘', 'ꮻ', '뮚', '䩵', '婔', '樷', '稖', '૱', '\u1ad0', '⪳', '㪒', 'ﴮ', '\ued0f', '\udd6c',
+		'쵍', '붪', '궋', '鷨', '跉', '簦', '氇', '層', '䱅', '㲢', 'ⲃ', '᳠', 'ು', '\uef1f', '＾', '콝', '\udf7c', '꾛', '뾺',
+		'这', '鿸', '渗', '縶', '乕', '年', '⺓', '㺲', '໑', 'Ự' };
+
+	public static boolean checkCRC(String resultValue) {
+	        if (resultValue.length() <= 2)
+			return false;
+	        var firstValue = resultValue.substring(0, resultValue.length() - 2);
+		var lastValue = resultValue.substring(resultValue.length() - 2);
+		var pByte = firstValue.getBytes();
+		var returnV = calculateCRC(pByte);
+		var lastV = toHexString(lastValue);
+		var reV = Integer.parseInt(lastV, 16);
+		return reV == returnV;
+	}
+
+	public static byte[] getCRCByte(String command) {
+		var crcint = calculateCRC(command.getBytes());
+		var crclow = crcint & 255;
+		var crchigh = crcint >> 8 & 255;
+		return new byte[] { (byte) crchigh, (byte) crclow };
+	}
+
+	private static String toHexString(String s) {
+		StringBuilder result = new StringBuilder();
+
+		for (int i = 0; i < s.length(); ++i) {
+			var ch = (short) s.charAt(i);
+			if (ch < 0)
+				ch = (short) (ch + 256);
+
+			var chString = Integer.toHexString(ch);
+			if (chString.length() < 2)
+				chString = "0" + chString;
+
+			result.append(chString);
+		}
+
+		return result.toString();
+	}
+
+	private static int calculateCRC(byte[] pByte) {
+		try {
+			int len = pByte.length;
+			int i = 0;
+
+			int crc;
+			for (crc = 0; len-- != 0; ++i) {
+				int da = 255 & (255 & crc >> 8) >> 4;
+				crc <<= 4;
+				crc ^= crc_tb[255 & (da ^ pByte[i] >> 4)];
+				da = 255 & (255 & crc >> 8) >> 4;
+				crc <<= 4;
+				int temp = 255 & (da ^ pByte[i] & 15);
+				crc ^= crc_tb[temp];
+			}
+
+			int bCRCLow = 255 & crc;
+			int bCRCHign = 255 & crc >> 8;
+			if (bCRCLow == 40 || bCRCLow == 13 || bCRCLow == 10)
+				++bCRCLow;
+
+			if (bCRCHign == 40 || bCRCHign == 13 || bCRCHign == 10)
+				++bCRCHign;
+
+			crc = (255 & bCRCHign) << 8;
+			crc += bCRCLow;
+			return crc;
+		} catch (Exception e) {
+			e.printStackTrace();
+			return 0;
+		}
+	}
+}

test/src/test/mpp/MPP.java

@@ -0,0 +1,71 @@
+package test.mpp;
+
+import java.io.IOException;
+
+import gnu.io.CommPortIdentifier;
+import gnu.io.NoSuchPortException;
+import gnu.io.PortInUseException;
+import gnu.io.RXTXPort;
+
+public class MPP implements AutoCloseable {
+	private RXTXPort r;
+	private SerialHandler serialHandler;
+
+	public MPP(final String port) throws NoSuchPortException, PortInUseException {
+		r = CommPortIdentifier.getPortIdentifier(port).open(MPP.class.getSimpleName(), 1000); // calls nativeavailable
+		try {
+			/*
+			 * read(1) on hidraw devices does not work, so read(byte[]) must be done.  But
+			 * ioctl(…FIORDCHK, 0) also does not work, so to avoid calling RXTXPort.nativeavailable
+			 * threshold must be set.  It turns out that the received data arrives in batches of 8.
+			 */
+			r.enableReceiveThreshold(8);
+		} catch (Exception e) {
+			/*
+			 * IOException: Invalid argument in TimeoutThreshold, likewise for below.  The reason
+			 * is that RXTXPort.NativeEnableReceiveTimeoutThreshold aborts when tcgetattr() fails.
+			 * Why Excepiton and not IOException?  Because the declaration in RXTXPort.java for
+			 * native void NativeEnableReceiveTimeoutThreshold does not say it can throw an
+			 * exception, so it throws only RuntimeExceptions in theory and IOException in practice.
+			 */
+		}
+		try { // useful when the cable is unplugged or device is off
+			r.enableReceiveTimeout(1000);
+		} catch (Exception e) {} // as above
+		serialHandler = new SerialHandler(r.getInputStream(), r.getOutputStream());
+	}
+
+	public static void main(String[] args) {
+		final String port = args.length == 1 ? args[0] : "/dev/hidraw0";
+
+		try (MPP d = new MPP(port)) {
+			System.out.println("Main CPU Firmware:    " + d.command("QVFW"));
+			System.out.println("Another CPU Firmware: " + d.command("QVFW2"));
+			System.out.println("Device Protocol ID:   " + d.command("QPI"));
+			System.out.println("Device Serial Number: " + d.command("QID"));
+		} catch (NoSuchPortException e) {
+			System.err.println("No such port " + port + " " + e);
+		} catch (PortInUseException e) {
+			System.err.println("Port in use " + e);
+		}
+	}
+
+	public String command(String command) {
+		try {
+			return serialHandler.executeCommand(command);
+		} catch (IOException e) {
+			e.printStackTrace();
+			return "";
+		}
+	}
+
+	@Override
+	public void close() {
+		final RXTXPort localR = r;
+		if (localR != null) {
+			localR.close();
+			r = null;
+		}
+		serialHandler = null;
+	}
+}

test/src/test/mpp/README.md

@@ -0,0 +1,30 @@
+# Introduction
+
+This shows how to use a /dev/hidraw device in the example of idVendor=0665 (Cypress Semiconductor), idProduct=5161 (USB to Serial), bcdDevice= 0.02, USB device string Mfr=3, Product=1, SerialNumber=0.
+
+The device is embedded in inverters known as Axpert, Effekta, MPP, Voltronic, or even having no name.
+
+Communication with it can be done using a USB Type B cable, demonstrated herein.  It supports also communication over LAN cable, bluetooth, RS232.
+
+# Caveats imposed by the Linux Kernel
+
+* reading one byte or writing one byte does not work.
+* tcgetattr() and tcsetattr() also do not work.  tcgetattr() sets errno to EINVAL, but should set it to ENOTTY, cf. https://lore.kernel.org/linux-input/[email protected]/.
+* ioctl(,FIONREAD,) also does not work.
+* reading data arrives in batches of 8 bytes.
+
+# Implications for the implementation
+
+* Do not fetch one byte with RXTXPort.getInputStream().read(), do not use RXTXPort.getOutputStream.write(byte).
+* Avoid RXTXPort.nativeavailable() by utilizing enableReceiveThreshold(8).  It calls tcgetattr(), which throws an exception, but nevertheless sets the threshold.
+* To make progress, when the cable is unplugged, set enableReceiveTimeout(1000). It again throws an exception when invoking tcgetattr(), but nevertheless sets the timeout for select().
+
+# Building
+
+cd nrjavaserial/test/src
+javac test/mpp/CRCUtil.java test/mpp/SerialHandler.java
+java -classpath ../../build/libs/nrjavaserial-5.2.1.jar:. test/mpp/MPP.java
+
+To utilizie /dev/hidraw1, instead of the default /dev/hidraw0, use
+
+java -classpath ../../build/libs/nrjavaserial-5.2.1.jar:. test/mpp/MPP.java /dev/hidraw1

test/src/test/mpp/SerialHandler.java

@@ -0,0 +1,67 @@
+package test.mpp;
+// adapted from https://github.com/synogen/mpp/blob/master/src/main/java/org/mppsolartest/serial/SerialHandler.java
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+public class SerialHandler {
+	private InputStream input;
+	private OutputStream output;
+	private int errorCount = 0;
+
+	public SerialHandler(InputStream input, OutputStream output) {
+		this.input = input;
+		this.output = output;
+	}
+
+	public synchronized String executeCommand(String command) throws IOException {
+		var result = true;
+		try {
+			output.write(command.getBytes());
+			var crc = CRCUtil.getCRCByte(command);
+			// on /dev/hidraw writing one byte fails
+			// write(8, "\r", 1)	   = -1 EINVAL (Invalid argument)
+			byte[] hack = new byte[crc.length + 1];
+			System.arraycopy(crc, 0, hack, 0, crc.length);
+			hack[crc.length] = '\r';
+			output.write(hack);
+			/* This could be useful, when using MPP over LAN cable, RS232 or Bluetooth
+			 * try {  // on hidraw devices ioctl(8, TCSBRK, 1) causes "Invalid argument in nativeDrain"
+			 *	output.flush();
+			 * } catch (IOException e) { }
+			*/
+			var timeout = System.currentTimeMillis() + 3000L;
+			var sb = new StringBuilder();
+			var linebreak = false;
+			byte[] b = new byte[8];
+			outerloop:
+			while (System.currentTimeMillis() < timeout)
+				if (input.read(b) > 0) {
+					for (int by : b) {
+						if (by == 13) {
+							linebreak = true;
+							break outerloop;
+						}
+						sb.append((char) by);
+					}
+				}
+
+			if (!linebreak)
+				result = false;
+			var returnValue = sb.toString();
+			return CRCUtil.checkCRC(returnValue) ? returnValue.substring(1, returnValue.length() - 2) : "";
+		} catch (IOException e) {
+			result = false;
+			throw e;
+		} finally {
+			errorCount = result ? 0 : errorCount + 1;
+			if (errorCount >= 12)
+				System.err.println("[Serial] Communication failed " + Integer.toString(errorCount) + " times");
+		}
+	}
+
+	public int errorCount() {
+		return errorCount;
+	}
+}