[robotpy][examples] Split examples and snippets (#8944)

This also updates the bazel scripts to behave more like the C++ and Java
examples, and updates the copybara scripts to be able to sync up
`mostrobotpy`

robotpyExamples/examples/DutyCycleEncoder/robot.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+#
+# 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.
+#
+
+"""
+This example shows how to use a duty cycle encoder for devices such as
+an arm or elevator.
+"""
+
+import wpilib
+import wpimath
+
+FULL_RANGE = 1.3
+EXPECTED_ZERO = 0.0
+
+
+class MyRobot(wpilib.TimedRobot):
+    def __init__(self):
+        """Called once at the beginning of the robot program."""
+        super().__init__()
+
+        # 2nd parameter is the range of values. This sensor will output between
+        # 0 and the passed in value.
+        # 3rd parameter is the the physical value where you want "0" to be. How
+        # to measure this is fairly easy. Set the value to 0, place the mechanism
+        # where you want "0" to be, and observe the value on the dashboard, That
+        # is the value to enter for the 3rd parameter.
+        self.dutyCycleEncoder = wpilib.DutyCycleEncoder(0, FULL_RANGE, EXPECTED_ZERO)
+
+        # If you know the frequency of your sensor, uncomment the following
+        # method, and set the method to the frequency of your sensor.
+        # This will result in more stable readings from the sensor.
+        # Do note that occasionally the datasheet cannot be trusted
+        # and you should measure this value. You can do so with either
+        # an oscilloscope, or by observing the "Frequency" output
+        # on the dashboard while running this sample. If you find
+        # the value jumping between the 2 values, enter halfway between
+        # those values. This number doesn't have to be perfect,
+        # just having a fairly close value will make the output readings
+        # much more stable.
+        self.dutyCycleEncoder.setAssumedFrequency(967.8)
+
+    def robotPeriodic(self):
+        # Connected can be checked, and uses the frequency of the encoder
+        connected = self.dutyCycleEncoder.isConnected()
+
+        # Duty Cycle Frequency in Hz
+        frequency = self.dutyCycleEncoder.getFrequency()
+
+        # Output of encoder
+        output = self.dutyCycleEncoder.get()
+
+        # By default, the output will wrap around to the full range value
+        # when the sensor goes below 0. However, for moving mechanisms this
+        # is not usually ideal, as if 0 is set to a hard stop, its still
+        # possible for the sensor to move slightly past. If this happens
+        # The sensor will assume its now at the furthest away position,
+        # which control algorithms might not handle correctly. Therefore
+        # it can be a good idea to slightly shift the output so the sensor
+        # can go a bit negative before wrapping. Usually 10% or so is fine.
+        # This does not change where "0" is, so no calibration numbers need
+        # to be changed.
+        percentOfRange = FULL_RANGE * 0.1
+        shiftedOutput = wpimath.inputModulus(
+            output, 0 - percentOfRange, FULL_RANGE - percentOfRange
+        )
+
+        wpilib.SmartDashboard.putBoolean("Connected", connected)
+        wpilib.SmartDashboard.putNumber("Frequency", frequency)
+        wpilib.SmartDashboard.putNumber("Output", output)
+        wpilib.SmartDashboard.putNumber("ShiftedOutput", shiftedOutput)