[examples] Add Limit Switch snippets (#7946)

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/snippets/limitswitch/Main.java

@@ -0,0 +1,25 @@
+// 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 edu.wpi.first.wpilibj.snippets.limitswitch;
+
+import edu.wpi.first.wpilibj.RobotBase;
+
+/**
+ * Do NOT add any static variables to this class, or any initialization at all. Unless you know what
+ * you are doing, do not modify this file except to change the parameter class to the startRobot
+ * call.
+ */
+public final class Main {
+  private Main() {}
+
+  /**
+   * Main initialization function. Do not perform any initialization here.
+   *
+   * <p>If you change your main robot class, change the parameter type.
+   */
+  public static void main(String... args) {
+    RobotBase.startRobot(Robot::new);
+  }
+}

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/snippets/limitswitch/Robot.java

@@ -0,0 +1,51 @@
+// 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 edu.wpi.first.wpilibj.snippets.limitswitch;
+
+import edu.wpi.first.wpilibj.DigitalInput;
+import edu.wpi.first.wpilibj.Joystick;
+import edu.wpi.first.wpilibj.TimedRobot;
+import edu.wpi.first.wpilibj.motorcontrol.PWMVictorSPX;
+
+/**
+ * Limit Switch snippets for frc-docs.
+ * https://docs.wpilib.org/en/stable/docs/software/hardware-apis/sensors/limit-switch.html
+ */
+public class Robot extends TimedRobot {
+  DigitalInput m_toplimitSwitch = new DigitalInput(0);
+  DigitalInput m_bottomlimitSwitch = new DigitalInput(1);
+  PWMVictorSPX m_motor = new PWMVictorSPX(0);
+  Joystick m_joystick = new Joystick(0);
+
+  @Override
+  public void teleopPeriodic() {
+    setMotorSpeed(m_joystick.getRawAxis(2));
+  }
+
+  /**
+   * Sets the motor speed based on joystick input while respecting limit switches.
+   *
+   * @param speed the desired speed of the motor, positive for up and negative for down
+   */
+  public void setMotorSpeed(double speed) {
+    if (speed > 0) {
+      if (m_toplimitSwitch.get()) {
+        // We are going up and top limit is tripped so stop
+        m_motor.set(0);
+      } else {
+        // We are going up but top limit is not tripped so go at commanded speed
+        m_motor.set(speed);
+      }
+    } else {
+      if (m_bottomlimitSwitch.get()) {
+        // We are going down and bottom limit is tripped so stop
+        m_motor.set(0);
+      } else {
+        // We are going down but bottom limit is not tripped so go at commanded speed
+        m_motor.set(speed);
+      }
+    }
+  }
+}

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/snippets/snippets.json

@@ -57,5 +57,16 @@
     "foldername": "encoderhoming",
     "gradlebase": "java",
     "mainclass": "Main"
+  },
+  {
+    "name": "LimitSwitch",
+    "description": "Snippets of Limit Switch for frc-docs.",
+    "tags": [
+      "Hardware",
+      "Digital Input"
+    ],
+    "foldername": "limitswitch",
+    "gradlebase": "java",
+    "mainclass": "Main"
   }
 ]