allwpilib/eclipse-plugins/edu.wpi.first.wpilib.plugins.cpp/resources/templates/examples/Relay/src/Robot.cpp

#include "WPILib.h"

/**
 * This is a sample program which uses joystick buttons to control a relay.
 * A Relay (generally a spike) has two outputs, each of which can be at either
 *   0V or 12V and so can be used for actions such as turning a motor off,
 *   full forwards, or full reverse, and is generally used on the compressor.
 * This program uses two buttons on a joystick and each button corresponds to
 *   one output; pressing the button sets the output to 12V and releasing sets
 *   it to 0V.
 * During Operator Control, the loop waits for a brief time before continuing
 *   in order to allow other threads to run. This is generally a good idea,
 *   especially as joystick values are only received every 20ms.
 */
class Robot: public SampleRobot
{
	// Joystick with which to control the relay.
	Joystick m_stick;

	// Relay to use for the
	Relay m_relay;

	// Numbers of the buttons to be used for controlling the Relay.
	const int kRelayForwardButton = 1;
	const int kRelayReverseButton = 2;

	// Update every 5milliseconds/0.005 seconds.
	const double kUpdatePeriod = 0.005;

public:
	Robot() :
			m_stick(0), // Use joystick on port 0.
			m_relay(0)  // Relay on port 0.
	{
	}

	/**
	 * Control a Relay using Joystick buttons.
	 */
	void OperatorControl()
	{
		while (IsOperatorControl() && IsEnabled())
		{
			// Retrieve the button values. GetRawButton will return
			//   true if the button is pressed and false if not.
			bool forward = m_stick.GetRawButton(kRelayForwardButton);
			bool reverse = m_stick.GetRawButton(kRelayReverseButton);

			// Depending on the button values, we want to use one of
			//   kOn, kOff, kForward, or kReverse.
			// kOn sets both outputs to 12V, kOff sets both to 0V,
			//   kForward sets forward to 12V and reverse to 0V, and
			//   kReverse sets reverse to 12V and forward to 0V.
			if (forward && reverse)
				m_relay.Set(Relay::kOn);
			else if (forward)
				m_relay.Set(Relay::kForward);
			else if (reverse)
				m_relay.Set(Relay::kReverse);
			else
				m_relay.Set(Relay::kOff);

			// Insert 5ms delay in loop.
			Wait(kUpdatePeriod);
		}
	}
};

START_ROBOT_CLASS(Robot);