Page 58 - The Definitive Guide to Building Java Robots

Preston_5564C02.fm Page 39 Wednesday, September 14, 2005 5:42 AM

CHAPTER 2 ■ SERIAL COMMUNICATION 39

test1:
SEROUT 16,16468,["a"]
GOTO main
test2:
SEROUT 16,16468,["b"]
GOTO main
getCompass:
SEROUT 16,16468,["180"]
GOTO main
The next class will communicate with the BASIC Stamp program we just created. It has a
single field, the StandardSerialPort called sPort. In the constructor, we create the port with an
int 1 corresponding to COM1 in Windows XP. Then we set the DTR to false because having it
true sets the Stamp to program mode, which we don’t want. Then we pause for 125 milliseconds to
give the port time to respond.
The next method, test(), returns a string. The expected string will either be “a” or “b”
depending on what was sent, because the Stamp program in the previous example just knows
how to return those two strings.
We will also add the close() method to close the StandardSerialPort, sPort.
In the main method, we will send to the test method bytes 101 and 102. We can also catch
any exception that could occur by using the StandardSerialPort. (See Example 2-10.)

Example 2-10. StampSerialTest.Java
package com.scottpreston.javarobot.chapter2;

public class StampSerialTest {
private StandardSerialPort sPort;

public StampSerialTest() throws Exception {
sPort = new StandardSerialPort(1);
sPort.setDTR(false);
Utils.pause(125);

}

public String test(byte something) throws Exception {
byte[] a = { something };
sPort.write(a);
Utils.pause(100);
return sPort.readString();
}
public void close() {
sPort.close();
}