[examples] Add communication examples (e.g. arduino) (#2500)

Co-authored-by: Andrew Dassonville <dassonville.andrew@gmail.com>

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/digitalcommunication/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.examples.digitalcommunication;
+
+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/examples/digitalcommunication/Robot.java

@@ -0,0 +1,42 @@
+// 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.examples.digitalcommunication;
+
+import edu.wpi.first.wpilibj.DigitalOutput;
+import edu.wpi.first.wpilibj.DriverStation;
+import edu.wpi.first.wpilibj.TimedRobot;
+
+/**
+ * This is a sample program demonstrating how to communicate to a light controller from the robot
+ * code using the roboRIO's DIO ports.
+ */
+public class Robot extends TimedRobot {
+  // define ports for digitalcommunication with light controller
+  private static final int kAlliancePort = 0;
+  private static final int kEnabledPort = 1;
+  private static final int kAutonomousPort = 2;
+  private static final int kAlertPort = 3;
+
+  private final DigitalOutput m_allianceOutput = new DigitalOutput(kAlliancePort);
+  private final DigitalOutput m_enabledOutput = new DigitalOutput(kEnabledPort);
+  private final DigitalOutput m_autonomousOutput = new DigitalOutput(kAutonomousPort);
+  private final DigitalOutput m_alertOutput = new DigitalOutput(kAlertPort);
+
+  @Override
+  public void robotPeriodic() {
+    // pull alliance port high if on red alliance, pull low if on blue alliance
+    m_allianceOutput.set(DriverStation.getAlliance() == DriverStation.Alliance.Red);
+
+    // pull enabled port high if enabled, low if disabled
+    m_enabledOutput.set(DriverStation.isEnabled());
+
+    // pull auto port high if in autonomous, low if in teleop (or disabled)
+    m_autonomousOutput.set(DriverStation.isAutonomous());
+
+    // pull alert port high if match time remaining is between 30 and 25 seconds
+    var matchTime = DriverStation.getMatchTime();
+    m_alertOutput.set(matchTime <= 30 && matchTime >= 25);
+  }
+}

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

@@ -770,5 +770,27 @@
     "gradlebase": "javaromi",
     "mainclass": "Main",
     "commandversion": 2
+  },
+  {
+    "name": "Digital Communication Sample",
+    "description": "An example program that communicates with external devices (such as an Arduino) using the roboRIO's DIO",
+    "tags": [
+      "Digital"
+    ],
+    "foldername": "digitalcommunication",
+    "gradlebase": "java",
+    "commandversion": 2,
+    "mainclass": "Main"
+  },
+  {
+    "name": "I2C Communication Sample",
+    "description": "An example program that communicates with external devices (such as an Arduino) using the roboRIO's I2C port",
+    "tags": [
+      "I2C"
+    ],
+    "foldername": "i2ccommunication",
+    "gradlebase": "java",
+    "commandversion": 2,
+    "mainclass": "Main"
   }
 ]

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/i2ccommunication/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.examples.i2ccommunication;
+
+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/examples/i2ccommunication/Robot.java

@@ -0,0 +1,57 @@
+// 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.examples.i2ccommunication;
+
+import edu.wpi.first.wpilibj.DriverStation;
+import edu.wpi.first.wpilibj.I2C;
+import edu.wpi.first.wpilibj.TimedRobot;
+
+/**
+ * This is a sample program demonstrating how to communicate to a light controller from the robot
+ * code using the roboRIO's I2C port.
+ */
+public class Robot extends TimedRobot {
+  private static int kDeviceAddress = 4;
+
+  private static I2C m_arduino = new I2C(I2C.Port.kOnboard, kDeviceAddress);
+
+  private void writeString(String input) {
+    // Creates a char array from the input string
+    char[] chars = input.toCharArray();
+
+    // Creates a byte array from the char array
+    byte[] data = new byte[chars.length];
+
+    // Adds each character
+    for (int i = 0; i < chars.length; i++) {
+      data[i] = (byte) chars[i];
+    }
+
+    // Writes bytes over I2C
+    m_arduino.transaction(data, data.length, null, 0);
+  }
+
+  @Override
+  public void robotPeriodic() {
+    // Creates a string to hold current robot state information, including
+    // alliance, enabled state, operation mode, and match time. The message
+    // is sent in format "AEM###" where A is the alliance color, (R)ed or
+    // (B)lue, E is the enabled state, (E)nabled or (D)isabled, M is the
+    // operation mode, (A)utonomous or (T)eleop, and ### is the zero-padded
+    // time remaining in the match.
+    //
+    // For example, "RET043" would indicate that the robot is on the red
+    // alliance, enabled in teleop mode, with 43 seconds left in the match.
+    StringBuilder stateMessage = new StringBuilder(6);
+
+    stateMessage
+        .append(DriverStation.getAlliance() == DriverStation.Alliance.Red ? "R" : "B")
+        .append(DriverStation.isEnabled() ? "E" : "D")
+        .append(DriverStation.isAutonomous() ? "A" : "T")
+        .append(String.format("%03d", (int) DriverStation.getMatchTime()));
+
+    writeString(stateMessage.toString());
+  }
+}