Subject:
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Transmitting time USB vs serial
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Newsgroups:
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lugnet.robotics.rcx.java
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Date:
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Sat, 28 Dec 2002 23:48:47 GMT
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Viewed:
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4682 times
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Hello,
I use lejos 2.1.0 and legousbtower 0.52 from the lejos distribution.
I measured the transmitting time of an Int from PC to RCX with the
attached programs and got the following result:
1. single integer (LED at the tower is off before pressing ENTER):
USB serial
6000-9000ms 300-700ms
2. multiple integers (pressing ENTER multiple times, LED keeps on):
USB serial
240ms 240ms
What can I do to decrease the response time in the first case with
the USB tower? Is it a problem of the driver or can I set the USB
tower to be always active? ("port.setListen( true )" doesn't help)
Thanks for any help,
Michael.
==================================================================
TowerTestPC.java:
==================================================================
import java.io.*;
import josx.rcxcomm.*;
public class TowerTestPC {
DataOutputStream out;
TowerTestPC() throws IOException {
RCXPort port = new RCXPort();
out = new DataOutputStream( port.getOutputStream() );
}
public static void main(String [] args) {
try {
TowerTestPC tt = new TowerTestPC();
BufferedReader in = new BufferedReader( new InputStreamReader( System.in ));
System.out.println("Press return to send Integer to RCX.");
while( true ) {
String line = in.readLine();
long before = System.currentTimeMillis();
tt.out.writeInt( 999 );
tt.out.flush();
long after = System.currentTimeMillis();
System.out.println("writeInt+flush: " + ( after - before ) + " ms");
}
} catch (IOException ioe) {};
}
}
==================================================================
TowerTestRCX.java:
==================================================================
import java.io.*;
import josx.platform.rcx.*;
import josx.rcxcomm.*;
public class TowerTestRCX {
DataInputStream in;
public TowerTestRCX() throws IOException {
RCXPort port = new RCXPort();
in = new DataInputStream( port.getInputStream() );
}
public static void main( String [] args ) {
try {
TowerTestRCX tt = new TowerTestRCX();
while( true ) {
int newpos = tt.in.readInt();
Sound.beep();
}
} catch (IOException e) {
Sound.beep();
Sound.beep();
Sound.beep();
}
}
}
==================================================================
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Message has 1 Reply:
 | | Re: Transmitting time USB vs serial
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| (...) Michael, I tried your programs on Windows and Linux. On Windows 98 the USB tower takes about one second to reply (990 - 1100ms). On Linux it took about 9 seconds as you indicate. This looks like a problem with the Linux USB driver. I will ask (...) (22 years ago, 5-Jan-03, to lugnet.robotics.rcx.java)
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