Week 3 HW

src/main/java/frc/robot/subsystems/ArmSubsystem.java

@@ -1,62 +1,47 @@
-// Copyright (c) FIRST and other WPILib contributors.
-// Open Source Software; you can modify and/or share it under the terms of
-// the WPILib BSD license file in the root directory of this project.
-
 package frc.robot.subsystems;
 
-import com.ctre.phoenix6.configs.Slot0Configs;
-import com.ctre.phoenix6.controls.PositionVoltage;
-import com.ctre.phoenix6.hardware.TalonFX;
 import edu.wpi.first.wpilibj2.command.SubsystemBase;
-import frc.robot.Constants;
+import com.ctre.phoenix6.hardware.TalonFX;
+import com.ctre.phoenix6.controls.PositionVoltage;
 
 public class ArmSubsystem extends SubsystemBase {
+  // 10 rotations of the arm motor = 1 radian of movement
+  // or about 0.1745 degrees per rotation
+  private static final int rotationsPerRadian = 10;
+  private static final double rotationsPerDegree = 0.1745;
+
   private final TalonFX motor;
+  // Set both so that both radians and degrees can be set
   private double targetRadians;
-
+  private double targetDegrees;
   private final PositionVoltage positionRequest;
 
   public ArmSubsystem() {
-    targetRadians = (3.14 / 2d);
-
     motor = new TalonFX(1);
-    Slot0Configs slot0 = new Slot0Configs();
-    slot0.kP = Constants.ArmConstants.kP;
-    slot0.kI = Constants.ArmConstants.kI;
-    slot0.kD = Constants.ArmConstants.kD;
-    motor.getConfigurator().apply(slot0);
 
     positionRequest = new PositionVoltage(0).withSlot(0);
   }
 
-  public void setAngle(double armRadians) {
-    targetRadians = armRadians;
+  // Allow choice between setting radians or degrees
+  public void setAngle(double angle, boolean radians) {
+    if (radians) {
+      targetRadians = angle;
+      motor.setControl(positionRequest.withPosition(angle * rotationsPerRadian));
+    } else {
+      targetDegrees = angle;
+      motor.setControl(positionRequest.withPosition(angle * rotationsPerDegree));
+    }
   }
 
-  public double getAngle() {
-    return motor.getRotorPosition().getValueAsDouble() / Constants.ArmConstants.rotationsPerRadian;
-  }
-
-  public void zeroEncoder() {
-    motor.setPosition(0.0);
-  }
-
-  public boolean isAtTargetAngle(double toleranceRadians) {
-    return Math.abs(getAngle() - targetRadians) <= toleranceRadians;
+  public double getAngle(boolean radians) {
+    if (radians) {
+      return motor.getRotorPosition().getValueAsDouble() / rotationsPerRadian;
+    } else {
+      return motor.getRotorPosition().getValueAsDouble() / rotationsPerDegree;
+    }
   }
 
   public void stop() {
-    setAngle(getAngle());
-  }
-
-  @Override
-  public void periodic() {
-    motor.setControl(positionRequest.withPosition(targetRadians * Constants.ArmConstants.rotationsPerRadian));
-    // This method will be called once per scheduler run
-  }
-
-  @Override
-  public void simulationPeriodic() {
-    // This method will be called once per scheduler run during simulation
+    setAngle(getAngle(true), true);
   }
 }

src/main/java/frc/robot/subsystems/week3-notes.txt

@@ -0,0 +1,22 @@
+CommandScheduler
+- Java class in charge of running commands
+- Regulates the lifecycle of commands
+    - Schedules commands for execution based on what buttons were pressed
+    - Runs scheduled commands
+    - Terminates commands that have finished execution
+- Also in charge of running the periodic() method of each subsystem
+
+Subsystems
+- Organization unit, groups together all related hardware
+- The CommandScheduler will either interrupt the current command or ignore the 
+  request when requested to run a command that requires an already-in-use subsystem
+- "Default commands" can be configured to run when no other command is currently running for a subsystem
+- Subsystems are created by extending WPILib's SubsystemBase class
+    - This is useful because subsystems tend to have many things in common
+- Hardware in a subsystem should only be accessed through its corresponding subsystem
+- Hardware is initialized in the constructor of its subsystem with a port number
+- Things that need to be called every cycle (~20ms) can be put into the periodic() method,
+  a method defined by the SubsystemBase class
+    - This includes logging and other simple tasks like updating values
+- The periodic() method should not move motors
+    - This is because the code in the periodic() method always runs, regardless of current execution state