Add encoder example

Author: fletch3555

encoder/robot.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+"""
+    Sample program displaying the value of a quadrature encoder on the SmartDashboard. Quadrature
+    Encoders are digital sensors which can detect the amount the encoder has rotated since starting
+    as well as the direction in which the encoder shaft is rotating. However, encoders can not tell
+    you the absolute position of the encoder shaft (ie, it considers where it starts to be the zero
+    position, no matter where it starts), and so can only tell you how much the encoder has rotated
+    since starting. Depending on the precision of an encoder, it will have fewer or greater ticks per
+    revolution; the number of ticks per revolution will affect the conversion between ticks and
+    distance, as specified by DistancePerPulse. One of the most common uses of encoders is in the
+    drivetrain, so that the distance that the robot drives can be precisely controlled during the
+    autonomous mode.
+"""
+
+import wpilib
+
+import math
+
+
+class MyRobot(wpilib.TimedRobot):
+
+    def robotInit(self):
+        """Robot initialization function"""
+
+        self.encoder = wpilib.Encoder(1, 2, False, wpilib.Encoder.EncodingType.k4X)
+
+        # Defines the number of samples to average when determining the rate.
+        # On a quadrature encoder, values range from 1-255;
+        # larger values result in smoother but potentially
+        # less accurate rates than lower values.
+        self.encoder.setSamplesToAverage(5)
+
+        # Defines how far the mechanism attached to the encoder moves per pulse. In
+        # this case, we assume that a 360 count encoder is directly
+        # attached to a 3 inch diameter (1.5inch radius) wheel,
+        # and that we want to measure distance in inches.
+        self.encoder.setDistancePerPulse(1.0 / 360.0 * 2.0 * math.pi * 1.5)
+
+        # Defines the lowest rate at which the encoder will
+        # not be considered stopped, for the purposes of
+        # the GetStopped() method. Units are in distance / second,
+        # where distance refers to the units of distance
+        # that you are using, in this case inches.
+        self.encoder.setMinRate(1.0)
+
+    def teleopPeriodic(self):
+        wpilib.SmartDashboard.putNumber("Encoder Distance", self.encoder.getDistance())
+        wpilib.SmartDashboard.putNumber("Encoder Rate", self.encoder.getRate())
+
+
+if __name__ == "__main__":
+    wpilib.run(MyRobot)

run_tests.sh

@@ -20,6 +20,7 @@ BASE_TESTS="
   elevator-profiled-pid
   elevator-simulation
   elevator-trapezoid-profile
+  encoder
   game-data
   getting-started
   gyro