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Overhauling debounce method and adding MIDI step sequencer example.

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sandyjmacdonald 2021-03-14 23:58:40 +00:00
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commit ec06dfa59c
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examples/midi-sequencer.py Normal file
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@ -0,0 +1,459 @@
# SPDX-FileCopyrightText: 2021 Sandy Macdonald
#
# SPDX-License-Identifier: MIT
# A MIDI step sequencer, with four tracks and eight steps per track.
# The eight steps are on the top two rows of keys. Steps can be toggled on by
# tapping a step's key. Active steps are indicated with a brighter LED, and the
# currently playing step in the sequence is shown with a moving LED across the
# eight steps.
# Each track is colour-coded: track 1 is orange, track 2 teal, track 3 is pink,
# and track 4 is green. Tracks can be selected by pressing and holding the
# bottom left orange track select key and then tapping one of the four track
# keys on the row above.
# The sequencer is started and stopped by tapping the bottom right key, which is
# red when the sequencer is stopped, and green when it is playing.
# The sequencer can be cleared by holding the track selector key (orange, bottom
# left) and then holding the start/stop key (red/green, bottom right).
# Tempo can be increased or decreased by holding the tempo selector key (teal,
# second from left, on the bottom row) and then tapping teal key on the row
# above to shift tempo down, or the pink key to shift it up. Tempo is increased/
# decreased by 5 BPM on each press.
# You'll need to connect Keybow 2040 to a computer running a DAW like Ableton,
# or other software synth, or to a hardware synth that accepts USB MIDI.
# Currently, all of the notes are C3 with a velocity of 127.
# Tracks' notes are sent on MIDI channels 1-4.
# Drop the keybow2040.py file into your `lib` folder on your `CIRCUITPY` drive,
# and then save this code in the `code.py` file
# NOTE! Requires the adafruit_midi CircuitPython library also!
import time
import board
from keybow2040 import Keybow2040
import usb_midi
import adafruit_midi
from adafruit_midi.note_off import NoteOff
from adafruit_midi.note_on import NoteOn
# These are the key numbers that represent each step in a track (the top two
# rows of four keys)
TRACK_KEYS = [3, 7, 11, 15, 2, 6, 10, 14]
# The colours for the LEDs on each track: orange, teal, pink, green
TRACK_COLOURS = [
(255, 255, 0),
(0, 255, 175),
(255, 0, 255),
(0, 255, 0)
]
# The MIDI channels for each track in turn: 1, 2, 3, 4
MIDI_CHANNELS = [0, 1, 2, 3]
# The bottom left key, orange. When pressed, it brings up the track selector
# keys, the four keys on the row above it.
TRACK_SELECTOR = 0
TRACK_SELECTOR_KEYS = [1, 5, 9, 13]
TRACK_SELECTOR_COLOUR = (255, 255, 0)
# The bottom right key. When pressed, it toggles the sequencer on or off. Green
# indicates that it is currently playing, red that it is stopped.
START_STOP = 12
START_COLOUR = (0, 255, 0)
STOP_COLOUR = (255, 0, 0)
# The key second from left on the bottom row, teal. When pressed, it brings up
# the tempo down/up buttons on the row above it. The left teal key shifts the
# tempo down, the right pink key shifts the tempo up.
TEMPO_SELECTOR = 4
TEMPO_SELECTOR_COLOUR = (0, 255, 175)
TEMPO_DOWN = 5
TEMPO_DOWN_COLOUR = (0, 255, 175)
TEMPO_UP = 9
TEMPO_UP_COLOUR = (255, 0, 255)
# The default starting BPM.
BPM = 85
# Dictates the time after which a key is "held".
KEY_HOLD_TIME = 0.25
# LED brightness settings for the track steps.
PLAY_BRIGHTNESS = 1.0
ACTIVE_BRIGHTNESS = 0.2
STEP_BRIGHTNESS = 0.05
class Sequencer(Keybow2040):
"""
Represents the sequencer, with a set of Track instances, which in turn have
a set of Step instances. This class is a subclass of the Keybow2040 class,
so it inherits all of its methods and key methods.
:param i2c: the I2C bus for Keybow 2040
"""
def __init__(self, *args, **kwargs):
super(Sequencer, self).__init__(*args, **kwargs)
# Holds the list of MIDI channels for the tracks.
self.midi_channels = []
# Set the MIDI channels up.
for channel in MIDI_CHANNELS:
midi = adafruit_midi.MIDI(midi_out=usb_midi.ports[1], out_channel=channel)
self.midi_channels.append(midi)
# Holds the list of tracks, a set of Track instances.
self.tracks = []
# Set the tracks up.
for i in range(4):
track = Track(self, i, i, TRACK_COLOURS[i])
self.tracks.append(track)
# Speed attributes.
self.bpm = BPM
self.tempo_selector = self.keys[TEMPO_SELECTOR]
self.tempo_selector.set_led(*TEMPO_SELECTOR_COLOUR)
self.tempo_select_active = False
self.tempo_down = self.keys[TEMPO_DOWN]
self.tempo_up = self.keys[TEMPO_UP]
# Step related stuff
self.num_steps = 8
self.this_step_num = 0
self.last_step_num = 0
# Is the sequencer running?
self.running = False
# Step time assumes the BPM is based on quarter notes.
self.step_time = 60.0 / self.bpm / (self.num_steps / 2)
self.last_step_time = time.monotonic()
# Set the default starting track to track 0
self.current_track = 0
# The start stop key.
self.start_stop = self.keys[START_STOP]
self.start_stop.set_led(*STOP_COLOUR)
# The track selector key.
self.track_selector = self.keys[TRACK_SELECTOR]
self.track_selector.set_led(*TRACK_SELECTOR_COLOUR)
self.track_selector_active = False
# These keys select and change the current track.
self.track_select_keys = []
for i in range(len(TRACK_SELECTOR_KEYS)):
track_key = self.keys[TRACK_SELECTOR_KEYS[i]]
track_key.rgb = TRACK_COLOURS[i]
self.track_select_keys.append(track_key)
# Set the key hold time for all the keys. A little shorter than the
# default for Keybow. Makes controlling the sequencer a bit more fluid.
for key in self.keys:
key.hold_time = KEY_HOLD_TIME
# Attach step_select function to keys in track steps. If pressed it
# toggles the state of the step.
for i in range(len(TRACK_KEYS)):
key = self.keys[TRACK_KEYS[i]]
@self.on_press(key)
def step_select(key):
step_num = TRACK_KEYS.index(key.number)
step = self.tracks[self.current_track].steps[step_num]
step.toggle()
# Attach hold function to track selector key that sets it active and
# lights the track select keys.
@self.on_hold(self.track_selector)
def track_selector_hold(key):
self.track_selector_active = True
for key in self.track_select_keys:
key.led_on()
# Attach release function to track selector key that sets it inactive
# and turns track select LEDs off.
@self.on_release(self.track_selector)
def track_selector_release(key):
self.track_selector_active = False
for key in self.track_select_keys:
key.led_off()
# Track 0 select.
@self.on_press(self.track_select_keys[0])
def track_select_0_press(key):
if self.track_selector_active:
self.current_track = 0
# Special case to handle track 1 select and tempo down.
# Pressing the tempo down key shifts the tempo down by
# 5 bpm each time it is pressed, with a lower limit of 5 BPM.
@self.on_press(self.track_select_keys[1])
def track_select_1_press(key):
if self.track_selector_active:
self.current_track = 1
else:
if self.tempo_select_active:
if self.bpm > 5:
self.bpm -= 5
# Special case to handle track 2 select and tempo up.
# Pressing the tempo up key shifts the tempo up by
# 5 bpm each time it is pressed, with an upper limit of 200 BPM.
@self.on_press(self.track_select_keys[2])
def track_select_2_press(key):
if self.track_selector_active:
self.current_track = 2
else:
if self.tempo_select_active:
if self.bpm < 200:
self.bpm += 5
# Track 3 select.
@self.on_press(self.track_select_keys[3])
def track_select_3_press(key):
if self.track_selector_active:
self.current_track = 3
# Attach press function to start/stop key that toggles whether the
# sequencer is running and toggles its colour between green (running)
# and red (not running).
@self.on_press(self.start_stop)
def start_stop_toggle(key):
if not self.track_selector_active:
if self.running:
self.running = False
key.set_led(*STOP_COLOUR)
else:
self.running = True
key.set_led(*START_COLOUR)
# Attach hold function, so that when the track selector key is held and
# the start/stop key is also held, clear all of the steps on all of the
# tracks.
@self.on_hold(self.start_stop)
def start_stop_hold(key):
if self.track_selector_active:
self.clear_tracks()
# Attach hold function that lights the tempo down/up keys when the
# tempo selector key is held.
@self.on_hold(self.tempo_selector)
def tempo_selector_hold(key):
self.tempo_select_active = True
self.tempo_down.set_led(*TEMPO_DOWN_COLOUR)
self.tempo_up.set_led(*TEMPO_UP_COLOUR)
# Attach release function that furns off the tempo down/up LEDs.
@self.on_release(self.tempo_selector)
def tempo_selector_release(key):
self.tempo_select_active = False
self.tempo_down.led_off()
self.tempo_up.led_off()
def update(self):
# Update the superclass (Keybow2040).
super(Sequencer, self).update()
if self.running:
# Keep track of current time.
current_time = time.monotonic()
# If a step has elapsed...
if current_time - self.last_step_time > self.step_time:
for track in self.tracks:
if track.active:
# Turn last step off.
last_step = track.steps[self.last_step_num]
last_step.playing = False
last_step.update()
last_note = last_step.note
# If last step is active, send MIDI note off message.
if last_step.active:
self.midi_channels[track.channel].send(NoteOff(last_note, 0))
# Turn this step on.
this_step = track.steps[self.this_step_num]
this_step.playing = True
this_step.update()
this_note = this_step.note
this_vel = this_step.velocity
# If this step is active, send MIDI note on message.
if this_step.active:
self.midi_channels[track.channel].send(NoteOn(this_note, this_vel))
# This step is now the last step!
last_step = this_step
self.last_step_num = self.this_step_num
self.this_step_num += 1
# If we get to the end of the sequence, go back to the start.
if self.this_step_num == self.num_steps:
self.this_step_num = 0
# Keep track of last step time.
self.last_step_time = current_time
# Update the tracks.
for track in self.tracks:
track.update()
# Update the step_time, in case the BPM has been changed.
self.step_time = 60.0 / self.bpm / (self.num_steps / 2)
def clear_tracks(self):
# Clears the steps on all tracks.
for track in self.tracks:
track.clear_steps()
class Track:
"""
Represents a track on the sequencer.
:param sequencer: the parent sequencer instance
:param index: the index of the track, integer
:param channel: the MIDI channel, integer
:param rgb: the RGB colour of the track, tuple of R, G, B, 0-255.
"""
def __init__(self, sequencer, index, channel, rgb):
self.index = index
self.rgb = rgb
self.channel = channel
self.steps = []
self.sequencer = sequencer
# For each key in the track, create a Step instance and add to
# self.steps.
for i in range(len(TRACK_KEYS)):
index = i
key = sequencer.keys[TRACK_KEYS[i]]
step = Step(index, key, self)
self.steps.append(step)
# Default to having the track active.
self.active = True
self.focussed = False
def set_on(self):
# Toggle the track on.
self.active = True
def set_off(self):
# Toggle the track off.
self.active = False
def update(self):
# Make the current track focussed and update its steps.
if sequencer.current_track == self.index:
self.focussed = True
self.update_steps()
else:
self.focussed = False
def update_steps(self):
# Update a tracks steps.
for step in self.steps:
step.update()
def clear_steps(self):
# Clear a track's steps by setting them all to inactive.
for step in self.steps:
step.active = False
class Step:
"""
Represents a step on a track.
:param index: the index of the step, integer
:param key: the key attached to this step, integer
:param track: the track this step belongs to, Track instance.
"""
def __init__(self, index, key, track):
self.index = index
self.key = key
self.track = track
self.active = False
self.playing = False
self.velocity = 127
self.note = 60
self.rgb = self.track.rgb
self.sequencer = self.track.sequencer
def toggle(self):
# Toggle the step between active and inactive.
self.active = not self.active
def state(self):
# Returns the state of the track (active/inactve).
return self.active
def set_led(self, r, g, b, brightness):
# Set the step's LED. Has an additional brightness parameter from 0.0
# (off) to 1.0 (full brightness for the colour).
r, g, b = [int(c * brightness) for c in (r, g, b)]
self.key.set_led(r, g, b)
def update(self):
# Update the step. Pretty much just handles the LEDs.
r, g, b = self.rgb
# If this step's track is focussed...
if self.track.focussed:
# Only update the LEDs when the sequencer is running.
if self.sequencer.running:
# Make an active step that is currently being played full
# brightness.
if self.playing and self.active:
self.set_led(r, g, b, PLAY_BRIGHTNESS)
# Make an inactive step that is "playing" (the current step)
# the dimmest brightness, but bright enough to indicate the
# step the sequencer is on.
if self.playing and not self.active:
self.set_led(r, g, b, STEP_BRIGHTNESS)
# Make an active step that is not playing a low-medium
# brightness to indicate that it is toggled active.
if not self.playing and self.active:
self.set_led(r, g, b, ACTIVE_BRIGHTNESS)
# Turn not playing, not active steps off.
if not self.playing and not self.active:
self.set_led(0, 0, 0, 0)
# If the sequencer is not running, still show the active steps.
elif not self.sequencer.running:
if self.active:
self.set_led(r, g, b, 0.3)
else:
self.set_led(0, 0, 0, 0)
# Set up Keybow
i2c = board.I2C()
# Instatiate the sequencer.
sequencer = Sequencer(i2c)
while True:
# Always remember to call sequencer.update() on every iteration of the main
# loop, otherwise NOTHING WILL WORK!
sequencer.update()

28
keybow2040.py
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@ -55,7 +55,7 @@ _PINS = [board.SW0,
NUM_KEYS = 16
class Keybow2040:
class Keybow2040(object):
"""
Represents a Keybow 2040 and hence a set of Key instances with
associated LEDs and key behaviours.
@ -67,6 +67,7 @@ class Keybow2040:
self.display = keybow2040.Keybow2040(i2c)
self.keys = []
self.time_of_last_press = time.monotonic()
self.time_since_last_press = None
self.led_sleep_enabled = False
self.led_sleep_time = 60
self.sleeping = False
@ -91,6 +92,8 @@ class Keybow2040:
self.time_of_last_press = time.monotonic()
self.sleeping = False
self.time_since_last_press = time.monotonic() - self.time_of_last_press
# If LED sleep is enabled, but not engaged, check if enough time
# has elapsed to engage sleep. If engaged, record the state of the
# LEDs, so it can be restored on wake.
@ -269,7 +272,8 @@ class Key:
self.state = 0
self.pressed = 0
self.last_state = None
self.time_pressed = None
self.time_of_last_press = time.monotonic()
self.time_since_last_press = None
self.time_held_for = 0
self.held = False
self.hold_time = 0.75
@ -285,6 +289,8 @@ class Key:
self.hold_function = None
self.press_func_fired = False
self.hold_func_fired = False
self.debounce = 0.125
self.key_locked = False
def get_state(self):
# Returns the state of the key (0=not pressed, 1=pressed).
@ -295,16 +301,24 @@ class Key:
# Updates the state of the key and updates all of its
# attributes.
self.time_since_last_press = time.monotonic() - self.time_of_last_press
# Keys get locked during the debounce time.
if self.time_since_last_press < self.debounce:
self.key_locked = True
else:
self.key_locked = False
self.state = self.get_state()
self.pressed = self.state
update_time = time.monotonic()
# If there's a `press_function` attached, then call it,
# returning the key object and the pressed state.
if self.press_function is not None and self.pressed and not self.press_func_fired:
if self.press_function is not None and self.pressed and not self.press_func_fired and not self.key_locked:
self.press_function(self)
self.press_func_fired = True
time.sleep(0.05) # A little debounce
# time.sleep(0.05) # A little debounce
# If the key has been pressed and releases, then call
# the `release_function`, if one is attached.
@ -319,15 +333,15 @@ class Key:
self.last_state = False
# If the key has just been pressed, then record the
# `time_pressed`, and update last_state.
# `time_of_last_press`, and update last_state.
elif self.pressed and self.last_state == False:
self.time_pressed = update_time
self.time_of_last_press = update_time
self.last_state = True
# If the key is pressed and held, then update the
# `time_held_for` variable.
elif self.pressed and self.last_state == True:
self.time_held_for = update_time - self.time_pressed
self.time_held_for = update_time - self.time_of_last_press
self.last_state = True
# If the `hold_time` theshold is crossed, then call the