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Added square wave functionality to play tone. #116

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Merged
merged 8 commits into from
May 9, 2022
Merged

Added square wave functionality to play tone. #116

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2759f47
Added square wave functionality to play tone.
ryanskeith May 3, 2022
1fa20bb
Fixing pylint statement because of black.
ryanskeith May 3, 2022
36bbb56
Removing unncessary variable.
ryanskeith May 3, 2022
dd3b5a3
Removing duplicate code.
ryanskeith May 3, 2022
b508e65
Blackened.
ryanskeith May 3, 2022
eb52cea
Adding SPDX line for myself.
ryanskeith May 3, 2022
74b8dd3
Changing from string to number format for waveform selection.
ryanskeith May 3, 2022
3a4b2b3
Fixed linting error. Blackened.
ryanskeith May 3, 2022
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41 changes: 29 additions & 12 deletions adafruit_circuitplayground/circuit_playground_base.py
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
# SPDX-FileCopyrightText: 2016 Scott Shawcroft for Adafruit Industries
# SPDX-FileCopyrightText: 2017-2019 Kattni Rembor for Adafruit Industries
# SPDX-FileCopyrightText: 2022 Ryan Keith for Adafruit Industries
#
# SPDX-License-Identifier: MIT

Expand All @@ -15,7 +16,7 @@
* `Circuit Playground Express <https://www.adafruit.com/product/3333>`_
* `Circuit Playground Bluefruit <https://www.adafruit.com/product/4333>`_.

* Author(s): Kattni Rembor, Scott Shawcroft
* Author(s): Kattni Rembor, Scott Shawcroft, Ryan Keith
"""

import math
Expand Down Expand Up @@ -102,8 +103,8 @@ def __init__(self):
self._speaker_enable = digitalio.DigitalInOut(board.SPEAKER_ENABLE)
self._speaker_enable.switch_to_output(value=False)
self._sample = None
self._sine_wave = None
self._sine_wave_sample = None
self._wave = None
self._wave_sample = None

# Initialise tap:
self._detect_taps = 1
Expand Down Expand Up @@ -689,23 +690,38 @@ def red_led(self, value):
@staticmethod
def _sine_sample(length):
tone_volume = (2**15) - 1
# Amplitude shift up in order to not have negative numbers
shift = 2**15
for i in range(length):
yield int(tone_volume * math.sin(2 * math.pi * (i / length)) + shift)

def _generate_sample(self, length=100):
@staticmethod
def _square_sample(length):
# Square waves are MUCH louder than then sine
tone_volume = (2**16) - 1
half_length = length // 2
for _ in range(half_length):
yield tone_volume
for _ in range(half_length):
yield 0

def _generate_sample(self, length=100, waveform="sine"):
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waveform could take constant values instead of a string.

I don't know if strictly better one way or the other but I tend to try to use constant number values with descriptively named variables instead of strings when I write code like this.

I'm not sure my tendencies are worth holding this up over though so we can see if anyone else has thoughts on it.

i.e usage would look something like:

circuitplayground.start_tone(234, circuitplayground.SINE_WAVEFORM)

and the value can then be a constant int rather than a string.

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That's a great idea as well. Is there an enum type in circuit python?

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I don't think we have enum, but we do have a const that is inherited from micropython: https://docs.circuitpython.org/en/latest/docs/library/micropython.html?#micropython.const

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since the variable names may take some space as well it may be worthwhile to go with a more shorthand version like SINE_WAVE instead of SINE_WAVEFORM as well. Every bit counts to an extent here.

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That is a good idea. I will look over variable names.

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@dhalbert dhalbert May 3, 2022 •
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SINE_WAVEFORM, etc. are going to be the equivalent of strings, so you will not gain space, unfortunately, I think. The names need to be available at run time.

if self._sample is not None:
return
self._sine_wave = array.array("H", self._sine_sample(length))
if waveform == "square":
self._wave = array.array("H", self._square_sample(length))
else:
self._wave = array.array("H", self._sine_sample(length))
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This may shrink things enough to fit

Suggested change
if waveform == "square":
self._wave = array.array("H", self._square_sample(length))
else:
self._wave = array.array("H", self._sine_sample(length))
self._wave = array.array("H", self._square_sample(length) if waveform == "square" else self._sine_sample(length))

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There may be similar refactorings in the Python code that would save a few bytes here and there.

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I wasn't sure if ternary operator worked in Circuit Python. I wrote it this way if anyone else wanted to add different shaped waves down the line. If it works, great but to me the sound difference isn't that big. Square definitely sounds more ragged than sine but that could be that the code is driving it rather hard.

self._sample = self._audio_out(board.SPEAKER) # pylint: disable=not-callable
self._sine_wave_sample = audiocore.RawSample(self._sine_wave)
self._wave_sample = audiocore.RawSample(self._wave)

def play_tone(self, frequency, duration):
def play_tone(self, frequency, duration, waveform="sine"):
"""Produce a tone using the speaker. Try changing frequency to change
the pitch of the tone.

:param int frequency: The frequency of the tone in Hz
:param float duration: The duration of the tone in seconds
:param str waveform: Type of waveform to be generated [sine, square]. Default = sine.

.. image :: ../docs/_static/speaker.jpg
:alt: Onboard speaker
Expand All @@ -719,15 +735,16 @@ def play_tone(self, frequency, duration):
cp.play_tone(440, 1)
"""
# Play a tone of the specified frequency (hz).
self.start_tone(frequency)
self.start_tone(frequency, waveform)
time.sleep(duration)
self.stop_tone()

def start_tone(self, frequency):
def start_tone(self, frequency, waveform="sine"):
"""Produce a tone using the speaker. Try changing frequency to change
the pitch of the tone.

:param int frequency: The frequency of the tone in Hz
:param str waveform: Type of waveform to be generated [sine, square]. Default = sine.

.. image :: ../docs/_static/speaker.jpg
:alt: Onboard speaker
Expand All @@ -750,11 +767,11 @@ def start_tone(self, frequency):
length = 100
if length * frequency > 350000:
length = 350000 // frequency
self._generate_sample(length)
self._generate_sample(length, waveform)
# Start playing a tone of the specified frequency (hz).
self._sine_wave_sample.sample_rate = int(len(self._sine_wave) * frequency)
self._wave_sample.sample_rate = int(len(self._wave) * frequency)
if not self._sample.playing:
self._sample.play(self._sine_wave_sample, loop=True)
self._sample.play(self._wave_sample, loop=True)

def stop_tone(self):
"""Use with start_tone to stop the tone produced.
Expand Down