First, I'm using the gumstix product called RoboStix to read in values from DC brushless motor encoders.
Below, I have copied Java code from a book called "Java Robots" in order to communicate to the micro-controller via a USB port.
Not knowing anything about the encoders or this code, and all I am sort of confused on how to convert the voltage levels to bytes or rather how to interpret what the byte values will mean in the code.
package com.scottpreston.javarobot.chapter2;
public interface JSerialPort{
public byte[] read();
public String readString();
public void write(byte[] b) throws Exception;
public void close();
public void setDTR(boolean dtr);
public void setTimeout(int tOut);
public static final String READ_COMMAND = "r";
public static final String WRITE_COMMAND = "w";
public static final String WRITE_READ_COMMAND = "wr";
public byte[] read(byte[] b) throws Exception;
public String readString(byte[] b) throws Exception;
}
package com.scottpreston.javarobot.chapter2;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Enumeration;
import javax.comm.CommPortIdentifier;
import javax.comm.SerialPort;
import javax.comm.SerialPortEvent;
import javax.comm.SerialPortEventListener;
public class StandardSerialPort implements SerialPortEventListener,
JSerialPort {
private Enumeration portList;
private CommPortIdentifier portId;
private SerialPort serialPort;
private OutputStream outputStream;
private InputStream inputStream;
private byte[] readBuffer;
private boolean dataIn = false;
private byte[] currentWrite;
private int i = 0;
public StandardSerialPort(int id) throws Exception {
init(id, 9600);
}
public StandardSerialPort(int id, int baud) throws Exception {
init(id, baud);
}
private void init(int comID, int baud) {
String comIdAsString = new Integer(comID).toString();
try {
portList = CommPortIdentifier.getPortIdentifiers();
while (portList.hasMoreElements()) {
portId = (CommPortIdentifier) portList.nextElement();
if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
if (portId.getName().endsWith(comIdAsString)) {
// create serial port
serialPort = (SerialPort) portId.open(
"StandardSerialPort", 3000);
// set config parms
serialPort.setSerialPortParams(baud,
SerialPort.DATABITS_8, SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
serialPort
.setFlowControlMode(SerialPort.FLOWCONTROL_NONE);
Utils.pause(50);
// config output stream
outputStream = serialPort.getOutputStream();
// config input stream
inputStream = serialPort.getInputStream();
// add events listener
serialPort.addEventListener(this);
serialPort.notifyOnDataAvailable(true);
Thread.sleep(50); // waits till ports change state.
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
public byte[] read() {
while (!dataIn) {
try {
Thread.sleep(1);
} catch (Exception e) {
}
}
dataIn = false;
return readBuffer;
}
public String readString() {
byte[] b = read();
StringBuffer s = new StringBuffer();
for (int i = 0; i < b.length; i++) {
if (b != 0) {
int in = (int) b;
if (in < 0) {
in = in + 256;
}
s.append(in);
s.append("~");
}
}
s.deleteCharAt(s.length() - 1);
return s.toString();
}
public void write(byte[] b) throws Exception {
currentWrite = b;
outputStream.write(b);
}
public void close() {
serialPort.close();
}
public byte[] read(byte[] b) throws Exception {
// not used
return null;
}
public String readString(byte[] b) throws Exception {
// not used
return null;
}
public void serialEvent(SerialPortEvent event) {
if (event.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
readBuffer = new byte[32];
i = 0;
try {
while (inputStream.available() > 0) {
int numBytes = inputStream.read(readBuffer);
}
int byteCount = 0;
for (int i = 0; i < currentWrite.length; i++) {
if (currentWrite == readBuffer) {
byteCount++;
}
}
if (byteCount != currentWrite.length) {
dataIn = true;
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
public void setTimeout(int timeout) {
// not used
}
public void setDTR(boolean dtr) {
serialPort.setDTR(dtr);
}
public String getName() {
return serialPort.getName();
}
}
