Defining/Setting a motor in Java

Technical Java
1

I am trying to run a VERY SIMPLE piece of Java.
Its only goal is to set a motor’s speed to 0.5.
Yet I have difficulties with even this simple task:

package org.usfirst.frc.team4855.robot;

import edu.wpi.first.wpilibj.IterativeRobot;
import edu.wpi.first.wpilibj.Talon;

public class Robot extends IterativeRobot {

	Talon talonMotor;

    public void robotInit() {

    	talonMotor = new Talon(0);
    	
    }

    public void teleopInit(){

    	talonMotor.set(0.5);

    }

Not only does this not work but I get a whole bunch of crap in the driver station:

ERROR Unhandled exception: java.lang.RuntimeException: Code: -1029. HAL: Resource already allocated at [edu.wpi.first.wpilibj.hal.PWMJNI.allocatePWMChannel(Native Method), edu.wpi.first.wpilibj.PWM.initPWM(PWM.java:117), edu.wpi.first.wpilibj.PWM.<init>(PWM.java:134), edu.wpi.first.wpilibj.SafePWM.<init>(SafePWM.java:35), edu.wpi.first.wpilibj.Talon.<init>(Talon.java:51), org.usfirst.frc.team4855.robot.Robot.robotInit(Robot.java:31), edu.wpi.first.wpilibj.IterativeRobot.startCompetition(IterativeRobot.java:72), edu.wpi.first.wpilibj.RobotBase.main(RobotBase.java:241)]
WARNING: Robots don’t quit!

Give it enough time and the robot will just reach an emergency stopped state without any apparent reason.

What in the world am I doing wrong

2

First, the 50% code should be in teleopPeriodic, not init (so it keeps getting called over and over again).

Second, you’re creating the talon at least twice. Your code isn’t complete so I can’t see where else it’s being constructed.

3

Thanks, put the code in teleopPeriodic.

I’m confused with your second point. The code I posted is all the code there is.

4

I have always written it in one line directly under the class statement not in robotinit.

Talon motor = new Talon(0);

Your problem may be from splitting it up.

5

That shouldn’t cause it, his motor reference would just be null prior to calling robotInit().

6

The error stack shows Robot.java:31, meaning line 31. You don’t have 31 lines posted in your thread.

And you’re missing a curly brace to close the class. The above by itself wouldn’t compile.

7

That’s because I had a bunch of blank space and comments that I got rid of when I copied and pasted the code here

I’m no longer getting errors in the console after moving to teleopPeriodic. But the motors still won’t move.

I checked the motors earlier by hooking them up to our battery. They work fine…

8

I am having the same issue. I am trying to execute EXTREMELY basic code (operating a Victor). Yet, whenever I try to execute the code, nothing happens and my console gives no hints. Even the sample code does nothing to the robot right now. It successfully deploys yet does nothing.

9

Nevermind. It was a stupid electrical error. I thought I had checked the system thoroughly but apparently I hadn’t.

Thanks for letting me know it wasn’t the code’s fault.

10

Always is :slight_smile: