Code for statemachine CP101 guide

CP101_StateMachines/brute-force/code.py

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+"""
+New Year's Eve ball drop robot friend.
+
+Adafruit invests time and resources providing this open source code.
+Please support Adafruit and open source hardware by purchasing
+products from Adafruit!
+
+Written by Dave Astels for Adafruit Industries
+Copyright (c) 2018 Adafruit Industries
+Licensed under the MIT license.
+
+All text above must be included in any redistribution.
+"""
+
+# pylint: disable=global-statement
+
+import time
+import random
+import board
+from digitalio import DigitalInOut, Direction, Pull
+import busio
+import adafruit_ds3231
+import audioio
+import pulseio
+from adafruit_motor import servo
+import neopixel
+from debouncer import Debouncer
+
+# Set to false to disable testing/tracing code
+TESTING = True
+
+# Implementation dependant things to tweak
+NUM_PIXELS = 8               # number of neopixels in the striup
+DROP_THROTTLE = -0.2         # servo throttle during ball drop
+DROP_DURATION = 10.0         # how many seconds the ball takes to drop
+RAISE_THROTTLE = 0.3         # servo throttle while raising the ball
+FIREWORKS_DURATION = 60.0    # how many second the fireworks last
+
+# Pins
+NEOPIXEL_PIN = board.D5
+POWER_PIN = board.D10
+SWITCH_PIN = board.D9
+SERVO_PIN = board.A1
+
+# States
+WAITING_STATE = 0
+PAUSED_STATE = 1
+DROPPING_STATE = 2
+BURST_STATE = 3
+SHOWER_STATE = 4
+RAISING_STATE = 5
+IDLE_STATE = 6
+RESET_STATE = 7
+
+
+################################################################################
+# Setup hardware
+
+# Power to the speaker and neopixels must be enabled using this pin
+
+enable = DigitalInOut(POWER_PIN)
+enable.direction = Direction.OUTPUT
+enable.value = True
+
+i2c = busio.I2C(board.SCL, board.SDA)
+rtc = adafruit_ds3231.DS3231(i2c)
+
+audio = audioio.AudioOut(board.A0)
+
+strip = neopixel.NeoPixel(NEOPIXEL_PIN, NUM_PIXELS, brightness=1, auto_write=False)
+strip.fill(0)                          # NeoPixels off ASAP on startup
+strip.show()
+
+switch = Debouncer(SWITCH_PIN, Pull.UP, 0.01)
+
+# create a PWMOut object on Pin A2.
+pwm = pulseio.PWMOut(SERVO_PIN, duty_cycle=2 ** 15, frequency=50)
+
+# Create a servo object, my_servo.
+servo = servo.ContinuousServo(pwm)
+servo.throttle = 0.0
+
+# Set the time for testing
+# Once finished testing, the time can be set using the REPL using similar code
+if TESTING:
+    #                     year, mon, date, hour, min, sec, wday, yday, isdst
+    t = time.struct_time((2018,  12,   31,   23,  58,  55,    1,   -1,    -1))
+    # you must set year, mon, date, hour, min, sec and weekday
+    # yearday is not supported, isdst can be set but we don't do anything with it at this time
+    print("Setting time to:", t)
+    rtc.datetime = t
+    print()
+
+################################################################################
+# Variables
+
+firework_color = 0
+firework_step_time = 0
+burst_count = 0
+shower_count = 0
+firework_stop_time = 0
+pixel_count = min([NUM_PIXELS // 2, 20])
+pixels = []
+pixel_index = 0
+
+
+################################################################################
+# Support functions
+
+def log(s):
+    """Print the argument if testing/tracing is enabled."""
+    if TESTING:
+        print(s)
+
+# Random color
+
+def random_color_byte():
+    """ Return one of 32 evenly spaced byte values.
+    This provides random colors that are fairly distinctive."""
+    return random.randrange(0, 256, 16)
+
+def random_color():
+    """Return a random color"""
+    red = random_color_byte()
+    green = random_color_byte()
+    blue = random_color_byte()
+    return (red, green, blue)
+
+# Color cycling. See https://learn.adafruit.com/hacking-ikea-lamps-with-circuit-playground-express/lamp-it-up
+
+def wheel(pos):
+    # Input a value 0 to 255 to get a color value.
+    # The colours are a transition r - g - b - back to r.
+    if pos < 0 or pos > 255:
+        return 0, 0, 0
+    if pos < 85:
+        return int(255 - pos*3), int(pos*3), 0
+    if pos < 170:
+        pos -= 85
+        return 0, int(255 - pos*3), int(pos*3)
+    pos -= 170
+    return int(pos * 3), 0, int(255 - (pos*3))
+
+def cycle_sequence(seq):
+    while True:
+        for elem in seq:
+            yield elem
+
+def rainbow_lamp(seq):
+    g = cycle_sequence(seq)
+    while True:
+        strip.fill(wheel(next(g)))
+        strip.show()
+        yield
+
+# Fireworks effects
+
+def reset_fireworks(time_now):
+    """As indicated, reset the fireworks system's variables."""
+    global firework_color, burst_count, shower_count, firework_step_time
+    firework_color = random_color()
+    burst_count = 0
+    shower_count = 0
+    strip.fill(0)
+    strip.show()
+    firework_step_time = time_now + 0.05
+
+
+def burst(time_now):
+    """Show a burst of color on all pixels, fading in, holding briefly,
+    then fading out.  Each call to this does one step in that
+    process. Return True once the sequence is finished."""
+    global firework_step_time, burst_count, shower_count
+    log("burst %d" % (burst_count))
+    if burst_count == 0:
+        strip.brightness = 0.0
+        strip.fill(firework_color)
+    elif burst_count == 22:
+        shower_count = 0
+        firework_step_time = time_now + 0.3
+        return True
+    if time_now < firework_step_time:
+        return False
+    elif burst_count < 11:
+        strip.brightness = burst_count / 10.0
+        firework_step_time = time_now + 0.08
+    elif burst_count == 11:
+        firework_step_time = time_now + 0.3
+    elif burst_count > 11:
+        strip.brightness = 1.0 - ((burst_count - 11) / 10.0)
+        firework_step_time = time_now + 0.08
+    strip.show()
+    burst_count += 1
+    return False
+
+def shower(time_now):
+    """Show a shower of sparks effect.
+    Each call to this does one step in the process. Return True once the
+    sequence is finished."""
+    global firework_step_time, pixels, pixel_index, shower_count
+    log("Shower %d" % (shower_count))
+    if shower_count == 0:                 # Initialize on the first step
+        strip.fill(0)
+        strip.brightness = 1.0
+        pixels = [None] * pixel_count
+        pixel_index = 0
+    if time_now < firework_step_time:
+        return False
+    if shower_count == NUM_PIXELS:
+        strip.fill(0)
+        strip.show()
+        return True
+    if pixels[pixel_index]:
+        strip[pixels[pixel_index]] = 0
+    random_pixel = random.randrange(NUM_PIXELS)
+    pixels[pixel_index] = random_pixel
+    strip[random_pixel] = firework_color
+    strip.show()
+    pixel_index = (pixel_index + 1) % pixel_count
+    shower_count += 1
+    firework_step_time = time_now + 0.1
+    return False
+
+def start_playing(fname):
+    sound_file = open(fname, 'rb')
+    wav = audioio.WaveFile(sound_file)
+    audio.play(wav, loop=False)
+
+def stop_playing():
+    if audio.playing:
+        audio.stop()
+
+
+state = WAITING_STATE
+paused_state = None
+paused_servo = 0.0
+switch_pressed_at = 0
+drop_finish_time = 0
+
+while True:
+    test_trigger = False
+    now = time.monotonic()
+    t = rtc.datetime
+    switch.update()
+
+    # The machine sits in paused state until the switch is pressed again in
+    # which case the machine goes back to the state it was in when paused (and
+    # resumes the audio and servo as it was) or the switch is held for a second
+    # in which case it goes to the reset state.
+    if state == PAUSED_STATE:
+        log("Paused")
+        if switch.fell:
+            if audio.paused:
+                audio.resume()
+            servo.throttle = paused_servo
+            paused_servo = 0.0
+            state = paused_state
+        elif not switch.value:
+            if now - switch_pressed_at > 1.0:
+                state = RESET_STATE
+        continue
+
+    # There is a special check here for a switch press in any state other than
+    # waiting. If there is a press, the current state, audio, and servo values
+    # are saved and paused state is entered
+    if switch.fell and state != WAITING_STATE:
+        switch_pressed_at = now
+        paused_state = state
+        if audio.playing:
+            audio.pause()
+        paused_servo = servo.throttle
+        servo.throttle = 0.0
+        state = PAUSED_STATE
+        continue
+
+    # Waiting state handles waiting until 23:59 on NYE or until the switch is
+    # pressed. When either happens, the song is played and the servo starts
+    # droppping the ball. As well, a rainbow effect is started on the LEDs and
+    # the machine moves to dropping state.
+    if state == WAITING_STATE:
+        log("Waiting")
+        if switch.fell:
+            while not switch.rose:
+                switch.update()
+            test_trigger = True
+
+        if test_trigger or (t.tm_mday == 31 and
+                            t.tm_mon == 12 and
+                            t.tm_hour == 23 and
+                            t.tm_min == 59 and
+                            t.tm_sec == 50):
+            test_trigger = False
+            # Play the song
+            start_playing('./countdown.wav')
+
+            # Drop the ball
+            servo.throttle = DROP_THROTTLE
+
+            # color show in the ball
+            rainbow = rainbow_lamp(range(0, 256, 2))
+            log("1 minute to midnight")
+            rainbow_time = now + 0.1
+
+            drop_finish_time = now + DROP_DURATION
+            state = DROPPING_STATE
+
+    # In dropping the ball is dropping, colors are cycling, and the song is
+    # playing. After the machine has been in this state long enough (set by
+    # DROP_DURATION) it cleans up and switches to fireworks mode (burst to be
+    # exact).
+    elif state == DROPPING_STATE:
+        log("Dropping")
+        if now >= drop_finish_time:
+            log("***Midnight")
+            servo.throttle = 0.0
+            stop_playing()
+            start_playing('./Auld_Lang_Syne.wav')
+            reset_fireworks(now)
+            firework_stop_time = now + FIREWORKS_DURATION
+            state = BURST_STATE
+            continue
+        if now >= rainbow_time:
+            next(rainbow)
+            rainbow_time = now + 0.1
+
+    # This state shows a burst of light (vi the burst function. It stays in
+    # this mode until burst is finished, indicated by burst returning
+    # True. When that happens the machine moves to the shower state.
+    elif state == BURST_STATE:
+        log("Burst")
+        if burst(now):
+            state = SHOWER_STATE
+            shower_count = 0
+
+    # This state shows a shower-of-sparks effect until the shower function
+    # returns True. If it's time to stop the fireworks effects the machine
+    # moves to the idle state. Otherwise if loops back to the burst state.
+    elif state == SHOWER_STATE:
+        log("Shower")
+        if shower(now):
+            if now >= firework_stop_time:
+                state = IDLE_STATE
+            else:
+                state = BURST_STATE
+                reset_fireworks(now)
+
+    # The idle state currently just jumps into the waiting state.
+    elif state == IDLE_STATE:
+        log("Idle")
+        state = WAITING_STATE
+
+    # This state resets the LEDs and audio, starts the servo raising the ball
+    # and moves to the raising state.
+    elif state == RESET_STATE:
+        log("Reset")
+        strip.fill(0)
+        strip.brightness = 1.0
+        strip.show()
+        if audio.playing:
+            audio.stop()
+        servo.throttle = RAISE_THROTTLE
+        state = RAISING_STATE
+
+    # This state simply waits until the switch is released at which time it
+    # stops the servo and moves to the waiting state.
+    elif state == RAISING_STATE:
+        log("Raise")
+        if switch.rose:
+            servo.throttle = 0.0
+            state = WAITING_STATE

CP101_StateMachines/brute-force/debouncer.py

@@ -0,0 +1,92 @@
+"""
+GPIO Pin Debouncer
+
+Adafruit invests time and resources providing this open source code.
+Please support Adafruit and open source hardware by purchasing
+products from Adafruit!
+
+Written by Dave Astels for Adafruit Industries
+Copyright (c) 2018 Adafruit Industries
+Licensed under the MIT license.
+
+All text above must be included in any redistribution.
+"""
+
+import time
+import digitalio
+
+class Debouncer(object):
+    """Debounce an input pin"""
+
+    DEBOUNCED_STATE = 0x01
+    UNSTABLE_STATE = 0x02
+    CHANGED_STATE = 0x04
+
+
+    def __init__(self, pin, mode=None, interval=0.010):
+        """Make am instance.
+           :param int pin: the pin (from board) to debounce
+           :param int mode: digitalio.Pull.UP or .DOWN (default is no pull up/down)
+           :param int interval: bounce threshold in seconds (default is 0.010, i.e. 10 milliseconds)
+        """
+        self.state = 0x00
+        self.pin = digitalio.DigitalInOut(pin)
+        self.pin.direction = digitalio.Direction.INPUT
+        if mode != None:
+            self.pin.pull = mode
+        if self.pin.value:
+            self.__set_state(Debouncer.DEBOUNCED_STATE | Debouncer.UNSTABLE_STATE)
+        self.previous_time = 0
+        if interval is None:
+            self.interval = 0.010
+        else:
+            self.interval = interval
+
+
+    def __set_state(self, bits):
+        self.state |= bits
+
+
+    def __unset_state(self, bits):
+        self.state &= ~bits
+
+
+    def __toggle_state(self, bits):
+        self.state ^= bits
+
+
+    def __get_state(self, bits):
+        return (self.state & bits) != 0
+
+
+    def update(self):
+        """Update the debouncer state. Must be called before using any of the properties below"""
+        self.__unset_state(Debouncer.CHANGED_STATE)
+        current_state = self.pin.value
+        if current_state != self.__get_state(Debouncer.UNSTABLE_STATE):
+            self.previous_time = time.monotonic()
+            self.__toggle_state(Debouncer.UNSTABLE_STATE)
+        else:
+            if time.monotonic() - self.previous_time >= self.interval:
+                if current_state != self.__get_state(Debouncer.DEBOUNCED_STATE):
+                    self.previous_time = time.monotonic()
+                    self.__toggle_state(Debouncer.DEBOUNCED_STATE)
+                    self.__set_state(Debouncer.CHANGED_STATE)
+
+
+    @property
+    def value(self):
+        """Return the current debounced value of the input."""
+        return self.__get_state(Debouncer.DEBOUNCED_STATE)
+
+
+    @property
+    def rose(self):
+        """Return whether the debounced input went from low to high at the most recent update."""
+        return self.__get_state(self.DEBOUNCED_STATE) and self.__get_state(self.CHANGED_STATE)
+
+
+    @property
+    def fell(self):
+        """Return whether the debounced input went from high to low at the most recent update."""
+        return (not self.__get_state(self.DEBOUNCED_STATE)) and self.__get_state(self.CHANGED_STATE)

CP101_StateMachines/classes/code.py

@@ -0,0 +1,497 @@
+import time
+"""
+Class based state machine implementation
+
+Adafruit invests time and resources providing this open source code.
+Please support Adafruit and open source hardware by purchasing
+products from Adafruit!
+
+Written by Dave Astels for Adafruit Industries
+Copyright (c) 2018 Adafruit Industries
+Licensed under the MIT license.
+
+All text above must be included in any redistribution.
+"""
+
+import random
+import board
+from digitalio import DigitalInOut, Direction, Pull
+import busio
+import adafruit_ds3231
+import audioio
+import pulseio
+from adafruit_motor import servo
+import neopixel
+from debouncer import Debouncer
+
+# Set to false to disable testing/tracing code
+TESTING = True
+
+# Implementation dependant things to tweak
+NUM_PIXELS = 8               # number of neopixels in the striup
+DROP_THROTTLE = -0.2         # servo throttle during ball drop
+DROP_DURATION = 10.0         # how many seconds the ball takes to drop
+RAISE_THROTTLE = 0.3         # servo throttle while raising the ball
+FIREWORKS_DURATION = 60.0    # how many second the fireworks last
+
+# Pins
+NEOPIXEL_PIN = board.D5
+POWER_PIN = board.D10
+SWITCH_PIN = board.D9
+SERVO_PIN = board.A1
+
+################################################################################
+# Setup hardware
+
+# Power to the speaker and neopixels must be enabled using this pin
+
+enable = DigitalInOut(POWER_PIN)
+enable.direction = Direction.OUTPUT
+enable.value = True
+
+i2c = busio.I2C(board.SCL, board.SDA)
+rtc = adafruit_ds3231.DS3231(i2c)
+
+audio = audioio.AudioOut(board.A0)
+
+strip = neopixel.NeoPixel(NEOPIXEL_PIN, NUM_PIXELS, brightness=1, auto_write=False)
+strip.fill(0)                          # NeoPixels off ASAP on startup
+strip.show()
+
+switch = Debouncer(SWITCH_PIN, Pull.UP, 0.01)
+
+# create a PWMOut object on Pin A2.
+pwm = pulseio.PWMOut(SERVO_PIN, duty_cycle=2 ** 15, frequency=50)
+
+# Create a servo object, my_servo.
+servo = servo.ContinuousServo(pwm)
+servo.throttle = 0.0
+
+# Set the time for testing
+# Once finished testing, the time can be set using the REPL using similar code
+if TESTING:
+    #                     year, mon, date, hour, min, sec, wday, yday, isdst
+    t = time.struct_time((2018,  12,   31,   23,  58,  55,    1,   -1,    -1))
+    # you must set year, mon, date, hour, min, sec and weekday
+    # yearday is not supported, isdst can be set but we don't do anything with it at this time
+    print("Setting time to:", t)
+    rtc.datetime = t
+    print()
+
+################################################################################
+# Global Variables
+
+pixel_count = min([NUM_PIXELS // 2, 20])
+
+################################################################################
+# Support functions
+
+def log(s):
+    """Print the argument if testing/tracing is enabled."""
+    if TESTING:
+        print(s)
+
+# Random color
+
+def random_color_byte():
+    """ Return one of 32 evenly spaced byte values.
+    This provides random colors that are fairly distinctive."""
+    return random.randrange(0, 256, 16)
+
+def random_color():
+    """Return a random color"""
+    red = random_color_byte()
+    green = random_color_byte()
+    blue = random_color_byte()
+    return (red, green, blue)
+
+# Color cycling. See https://learn.adafruit.com/hacking-ikea-lamps-with-circuit-playground-express/lamp-it-up
+
+def wheel(pos):
+    # Input a value 0 to 255 to get a color value.
+    # The colours are a transition r - g - b - back to r.
+    if pos < 0 or pos > 255:
+        return 0, 0, 0
+    if pos < 85:
+        return int(255 - pos*3), int(pos*3), 0
+    if pos < 170:
+        pos -= 85
+        return 0, int(255 - pos*3), int(pos*3)
+    pos -= 170
+    return int(pos * 3), 0, int(255 - (pos*3))
+
+def cycle_sequence(seq):
+    while True:
+        for elem in seq:
+            yield elem
+
+def rainbow_lamp(seq):
+    g = cycle_sequence(seq)
+    while True:
+        strip.fill(wheel(next(g)))
+        strip.show()
+        yield
+
+# Fireworks effects
+
+def burst(machine, time_now):
+    """Show a burst of color on all pixels, fading in, holding briefly,
+    then fading out.  Each call to this does one step in that
+    process. Return True once the sequence is finished."""
+    if machine.burst_count == 0:
+        strip.brightness = 0.0
+        strip.fill(machine.firework_color)
+    elif machine.burst_count == 22:
+        machine.firework_step_time = time_now + 0.3
+        return True
+    if time_now < machine.firework_step_time:
+        return False
+    elif machine.burst_count < 11:
+        strip.brightness = machine.burst_count / 10.0
+        machine.firework_step_time = time_now + 0.08
+    elif machine.burst_count == 11:
+        machine.firework_step_time = time_now + 0.3
+    elif machine.burst_count > 11:
+        strip.brightness = 1.0 - ((machine.burst_count - 11) / 10.0)
+        machine.firework_step_time = time_now + 0.08
+    strip.show()
+    machine.burst_count += 1
+    return False
+
+def shower(machine, time_now):
+    """Show a shower of sparks effect.
+    Each call to this does one step in the process. Return True once the
+    sequence is finished."""
+    if machine.shower_count == 0:                 # Initialize on the first step
+        strip.fill(0)
+        strip.brightness = 1.0
+        machine.pixels = [None] * pixel_count
+        machine.pixel_index = 0
+    if time_now < machine.firework_step_time:
+        return False
+    if machine.shower_count == NUM_PIXELS:
+        strip.fill(0)
+        strip.show()
+        return True
+    if machine.pixels[machine.pixel_index]:
+        strip[machine.pixels[machine.pixel_index]] = 0
+    random_pixel = random.randrange(NUM_PIXELS)
+    machine.pixels[machine.pixel_index] = random_pixel
+    strip[random_pixel] = machine.firework_color
+    strip.show()
+    machine.pixel_index = (machine.pixel_index + 1) % pixel_count
+    machine.shower_count += 1
+    machine.firework_step_time = time_now + 0.1
+    return False
+
+def start_playing(fname):
+    sound_file = open(fname, 'rb')
+    wav = audioio.WaveFile(sound_file)
+    audio.play(wav, loop=False)
+
+def stop_playing():
+    if audio.playing:
+        audio.stop()
+
+
+################################################################################
+# State Machine
+
+class StateMachine(object):
+
+    def __init__(self):
+        self.state = None
+        self.states = {}
+        self.firework_color = 0
+        self.firework_step_time = 0
+        self.burst_count = 0
+        self.shower_count = 0
+        self.firework_stop_time = 0
+        self.paused_state = None
+        self.pixels = []
+        self.pixel_index = 0
+
+    def add_state(self, state):
+        self.states[state.name] = state
+
+    def go_to_state(self, state_name):
+        if self.state:
+            log('Exiting %s' % (self.state.name))
+            self.state.exit(self)
+        self.state = self.states[state_name]
+        log('Entering %s' % (self.state.name))
+        self.state.enter(self)
+
+    def update(self):
+        if self.state:
+            log('Updating %s' % (self.state.name))
+            self.state.update(self)
+
+    # When pausing, don't exit the state
+    def pause(self):
+        self.state = self.states['paused']
+        log('Pausing')
+        self.state.enter(self)
+
+    # When resuming, don't re-enter the state
+    def resume_state(self, state_name):
+        if self.state:
+            log('Exiting %s' % (self.state.name))
+            self.state.exit(self)
+        self.state = self.states[state_name]
+        log('Resuming %s' % (self.state.name))
+
+    def reset_fireworks(self):
+        """As indicated, reset the fireworks system's variables."""
+        self.firework_color = random_color()
+        self.burst_count = 0
+        self.shower_count = 0
+        self.firework_step_time = time.monotonic() + 0.05
+        strip.fill(0)
+        strip.show()
+
+
+
+
+################################################################################
+# States
+
+
+# Abstract parent state class.
+
+class State(object):
+
+    def __init__(self):
+        pass
+
+    @property
+    def name(self):
+        return ''
+
+    def enter(self, machine):
+        pass
+
+    def exit(self, machine):
+        pass
+
+    def update(self, machine):
+        if switch.fell:
+            machine.paused_state = machine.state.name
+            machine.pause()
+            return False
+        return True
+
+
+# Wait for 10 seconds to midnight or the witch to be pressed,
+# then drop the ball.
+
+class WaitingState(State):
+
+    @property
+    def name(self):
+        return 'waiting'
+
+    def enter(self, machine):
+        State.enter(self, machine)
+
+    def exit(self, machine):
+        State.exit(self, machine)
+
+    def almost_NY(self):
+        t = rtc.datetime
+        return (t.tm_mday == 31 and
+                t.tm_mon == 12 and
+                t.tm_hour == 23 and
+                t.tm_min == 59 and
+                t.tm_sec == 50)
+
+    def update(self, machine):
+        # No super call to check for switch press to pause
+        # switch press here drops the ball
+        if switch.fell or self.almost_NY():
+            machine.go_to_state('dropping')
+
+# Drop the ball, playing the countdown and showing
+# a rainbow effect.
+
+class DroppingState(State):
+
+    def __init__(self):
+        self.rainbow = None
+        self.rainbow_time = 0
+        self.drop_finish_time = 0
+
+    @property
+    def name(self):
+        return 'dropping'
+
+    def enter(self, machine):
+        State.enter(self, machine)
+        now = time.monotonic()
+        start_playing('./countdown.wav')
+        servo.throttle = DROP_THROTTLE
+        self.rainbow = rainbow_lamp(range(0, 256, 2))
+        self.rainbow_time = now + 0.1
+        self.drop_finish_time = now + DROP_DURATION
+
+    def exit(self, machine):
+        State.exit(self, machine)
+        now = time.monotonic()
+        servo.throttle = 0.0
+        stop_playing()
+        machine.reset_fireworks()
+        machine.firework_stop_time = now + FIREWORKS_DURATION
+
+    def update(self, machine):
+        if State.update(self, machine):
+            now = time.monotonic()
+            if now >= self.drop_finish_time:
+                machine.go_to_state('burst')
+            if now >= self.rainbow_time:
+                next(self.rainbow)
+                self.rainbow_time = now + 0.1
+
+
+# Show a fireworks explosion: a burst of color. Then switch to a shower of sparks.
+
+class BurstState(State):
+
+    @property
+    def name(self):
+        return 'burst'
+
+    def enter(self, machine):
+        State.enter(self, machine)
+
+    def exit(self, machine):
+        State.exit(self, machine)
+        machine.shower_count = 0
+
+    def update(self, machine):
+        if State.update(self, machine):
+            if burst(machine, time.monotonic()):
+                machine.go_to_state('shower')
+
+
+# Show a shower of sparks following an explosion
+
+class ShowerState(State):
+
+    @property
+    def name(self):
+        return 'shower'
+
+    def enter(self, machine):
+        State.enter(self, machine)
+
+    def exit(self, machine):
+        State.exit(self, machine)
+        machine.reset_fireworks()
+
+    def update(self, machine):
+        if State.update(self, machine):
+            if shower(machine, time.monotonic()):
+                if now >= machine.firework_stop_time:
+                    machine.go_to_state('idle')
+                else:
+                    machine.go_to_state('burst')
+
+
+# Do nothing, wait to be reset
+
+class IdleState(State):
+
+    @property
+    def name(self):
+        return 'idle'
+
+    def enter(self, machine):
+        State.enter(self, machine)
+
+    def exit(self, machine):
+        State.exit(self, machine)
+
+    def update(self, machine):
+        State.update(self, machine)
+
+
+# Reset the LEDs and audio, start the servo raising the ball
+# When the switch is released, stop the ball and move to waiting
+
+class RaisingState(State):
+
+    @property
+    def name(self):
+        return 'raising'
+
+    def enter(self, machine):
+        State.enter(self, machine)
+        strip.fill(0)
+        strip.brightness = 1.0
+        strip.show()
+        if audio.playing:
+            audio.stop()
+        servo.throttle = RAISE_THROTTLE
+
+    def exit(self, machine):
+        State.exit(self, machine)
+        servo.throttle = 0.0
+
+    def update(self, machine):
+        if State.update(self, machine):
+            if switch.rose:
+                machine.go_to_state('waiting')
+
+
+# Pause, resuming whem the switch is pressed again.
+# Reset if the switch has been held for a second.
+
+class PausedState(State):
+
+    @property
+    def __init__(self):
+        self.switch_pressed_at = 0
+        self.paused_servo = 0
+
+    def name(self):
+        return 'paused'
+
+    def enter(self, machine):
+        State.enter(self, machine)
+        self.switch_pressed_at = time.monotonic()
+        if audio.playing:
+            audio.pause()
+        self.paused_servo = servo.throttle
+        servo.throttle = 0.0
+
+    def exit(self, machine):
+        State.exit(self, machine)
+
+    def update(self, machine):
+        if switch.fell:
+            if audio.paused:
+                audio.resume()
+            servo.throttle = self.paused_servo
+            self.paused_servo = 0.0
+            machine.resume_state(machine.paused_state)
+        elif not switch.value:
+            if time.monotonic() - self.switch_pressed_at > 1.0:
+                machine.go_to_state('raising')
+
+################################################################################
+# Create the state machine
+
+machine = StateMachine()
+machine.add_state(WaitingState())
+machine.add_state(DroppingState())
+machine.add_state(BurstState())
+machine.add_state(ShowerState())
+machine.add_state(IdleState())
+machine.add_state(RaisingState())
+machine.add_state(PausedState())
+
+machine.go_to_state('waiting')
+
+while True:
+    switch.update()
+    machine.update()

CP101_StateMachines/classes/debouncer.py

@@ -0,0 +1,92 @@
+"""
+GPIO Pin Debouncer
+
+Adafruit invests time and resources providing this open source code.
+Please support Adafruit and open source hardware by purchasing
+products from Adafruit!
+
+Written by Dave Astels for Adafruit Industries
+Copyright (c) 2018 Adafruit Industries
+Licensed under the MIT license.
+
+All text above must be included in any redistribution.
+"""
+
+import time
+import digitalio
+
+class Debouncer(object):
+    """Debounce an input pin"""
+
+    DEBOUNCED_STATE = 0x01
+    UNSTABLE_STATE = 0x02
+    CHANGED_STATE = 0x04
+
+
+    def __init__(self, pin, mode=None, interval=0.010):
+        """Make am instance.
+           :param int pin: the pin (from board) to debounce
+           :param int mode: digitalio.Pull.UP or .DOWN (default is no pull up/down)
+           :param int interval: bounce threshold in seconds (default is 0.010, i.e. 10 milliseconds)
+        """
+        self.state = 0x00
+        self.pin = digitalio.DigitalInOut(pin)
+        self.pin.direction = digitalio.Direction.INPUT
+        if mode != None:
+            self.pin.pull = mode
+        if self.pin.value:
+            self.__set_state(Debouncer.DEBOUNCED_STATE | Debouncer.UNSTABLE_STATE)
+        self.previous_time = 0
+        if interval is None:
+            self.interval = 0.010
+        else:
+            self.interval = interval
+
+
+    def __set_state(self, bits):
+        self.state |= bits
+
+
+    def __unset_state(self, bits):
+        self.state &= ~bits
+
+
+    def __toggle_state(self, bits):
+        self.state ^= bits
+
+
+    def __get_state(self, bits):
+        return (self.state & bits) != 0
+
+
+    def update(self):
+        """Update the debouncer state. Must be called before using any of the properties below"""
+        self.__unset_state(Debouncer.CHANGED_STATE)
+        current_state = self.pin.value
+        if current_state != self.__get_state(Debouncer.UNSTABLE_STATE):
+            self.previous_time = time.monotonic()
+            self.__toggle_state(Debouncer.UNSTABLE_STATE)
+        else:
+            if time.monotonic() - self.previous_time >= self.interval:
+                if current_state != self.__get_state(Debouncer.DEBOUNCED_STATE):
+                    self.previous_time = time.monotonic()
+                    self.__toggle_state(Debouncer.DEBOUNCED_STATE)
+                    self.__set_state(Debouncer.CHANGED_STATE)
+
+
+    @property
+    def value(self):
+        """Return the current debounced value of the input."""
+        return self.__get_state(Debouncer.DEBOUNCED_STATE)
+
+
+    @property
+    def rose(self):
+        """Return whether the debounced input went from low to high at the most recent update."""
+        return self.__get_state(self.DEBOUNCED_STATE) and self.__get_state(self.CHANGED_STATE)
+
+
+    @property
+    def fell(self):
+        """Return whether the debounced input went from high to low at the most recent update."""
+        return (not self.__get_state(self.DEBOUNCED_STATE)) and self.__get_state(self.CHANGED_STATE)