Example program and output for TalonSRX current limit issue

TalonTestRobot.java

package org.team2767.thirdcoast;

import com.ctre.phoenix.ErrorCode;
import com.ctre.phoenix.motorcontrol.ControlMode;
import com.ctre.phoenix.motorcontrol.can.TalonSRX;
import edu.wpi.first.wpilibj.IterativeRobot;
import edu.wpi.first.wpilibj.Timer;

public class TalonTestRobot extends IterativeRobot {

  private TalonSRX talon;
  private Timer timer = new Timer();
  private double setpoint;

  @Override
  public void robotInit() {
    talon = new TalonSRX(11);
    ErrorCode err = talon.configVoltageCompSaturation(12, 10);
    check(err);
    err = talon.configContinuousCurrentLimit(50, 10);
    check(err);
    talon.enableCurrentLimit(true);
    talon.enableVoltageCompensation(true);
  }

  @Override
  public void teleopInit() {
    setpoint = 0.2;
    timer.start();
  }

  @Override
  public void teleopPeriodic() {
    // reverse Talon every 2 seconds
    setpoint *= timer.hasPeriodPassed(2) ? -1 : 1;
    talon.set(ControlMode.PercentOutput, setpoint);
  }

  private void check(ErrorCode code) {
    if (code != ErrorCode.OK) {
      System.out.println("Talon config error: " + code);
    }
  }
}

This test was set up to flip output between +/- 20% every 2 seconds. With current limit disabled we see expected behavior. With current limit enabled at 50 amps we see +/- 100% oscillation for approx 0.8 sec. before reversing.

The motor is turning a unloaded wheel (robot on blocks). Tested on multiple Talons.

To reproduce, compile and run example above with talon.enableCurrentLimit(false); and talon.enableCurrentLimit(true);. TalonSRX is factory reset before each run.

Video: https://youtu.be/E-3qkO6zzYU

With talon.enableCurrentLimit(false);

With talon.enableCurrentLimit(true);

Screenshots of roboRIO TalonSRX web pages

Adding this fixed the problem:

talon.configPeakCurrentDuration(0, 10);

However, a factory reset by itself did not fix the problem. I repeated this a couple of times:

1. Power-cycle with B/C button pressed - saw flashing green lights as expected.
2. Ran code without peak disable code, saw issue
3. Ran code with with peak disable code (as above), fixed issue
4. Ran code without peak disable code, still ran correctly as expected for persistent setting