Added relay example.

Author: mbardoe

relay/robot.py

@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+
+import wpilib
+
+
+class MyRobot(wpilib.TimedRobot):
+    """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.
+    """
+
+    def robotInit(self):
+        """Robot initialization function"""
+        # create Relay object
+        self.relay = wpilib.Relay(0)
+
+        # create joystick object
+        self.joystickChannel = 0  # usb number in DriverStation
+        self.joystick = wpilib.Joystick(self.joystickChannel)
+
+        # create variables to define the buttons
+        self.relayForwardButton = 1
+        self.relayReverseButton = 2
+
+    def teleopPeriodic(self):
+        """
+        The relay can be set several ways. It has two outputs which each can be set for either 0V or 12V.
+        This code uses buttons on a joystick to set each of the outputs.
+        """
+
+        forward = self.joystick.getRawButton(self.relayForwardButton)
+        reverse = self.joystick.getRawButton(self.relayReverseButton)
+
+        if forward and reverse:
+            self.relay.set(wpilib.Relay.Value.kOn)
+        elif forward:
+            self.relay.set(wpilib.Relay.Value.kForward)
+        elif reverse:
+            self.relay.set(wpilib.Relay.Value.kReverse)
+        else:
+            self.relay.set(wpilib.Relay.Value.kOff)
+
+
+if __name__ == "__main__":
+    wpilib.run(MyRobot)