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

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

wpilibcExamples/src/main/cpp/examples/DigitalCommunication/cpp/Robot.cpp

@@ -0,0 +1,46 @@
+// 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.
+
+#include <frc/DigitalOutput.h>
+#include <frc/DriverStation.h>
+#include <frc/TimedRobot.h>
+
+/**
+ * This is a sample program demonstrating how to communicate to a light
+ * controller from the robot code using the roboRIO's DIO ports.
+ */
+class Robot : public frc::TimedRobot {
+ public:
+  void RobotPeriodic() override {
+    // pull alliance port high if on red alliance, pull low if on blue alliance
+    m_allianceOutput.Set(frc::DriverStation::GetAlliance() ==
+                         frc::DriverStation::kRed);
+
+    // pull enabled port high if enabled, low if disabled
+    m_enabledOutput.Set(frc::DriverStation::IsEnabled());
+
+    // pull auto port high if in autonomous, low if in teleop (or disabled)
+    m_autonomousOutput.Set(frc::DriverStation::IsAutonomous());
+
+    // pull alert port high if match time remaining is between 30 and 25 seconds
+    auto matchTime = frc::DriverStation::GetMatchTime();
+    m_alertOutput.Set(matchTime <= 30 && matchTime >= 25);
+  }
+
+ private:
+  // define ports for communication with light controller
+  static constexpr int kAlliancePort = 0;
+  static constexpr int kEnabledPort = 1;
+  static constexpr int kAutonomousPort = 2;
+  static constexpr int kAlertPort = 3;
+
+  frc::DigitalOutput m_allianceOutput{kAlliancePort};
+  frc::DigitalOutput m_enabledOutput{kEnabledPort};
+  frc::DigitalOutput m_autonomousOutput{kAutonomousPort};
+  frc::DigitalOutput m_alertOutput{kAlertPort};
+};
+
+int main() {
+  return frc::StartRobot<Robot>();
+}