102 lines
2.5 KiB
Python
102 lines
2.5 KiB
Python
# SPDX-FileCopyrightText: 2018 Dave Astels for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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"""
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Outpout generator code for signal generator.
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Adafruit invests time and resources providing this open source code.
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Please support Adafruit and open source hardware by purchasing
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products from Adafruit!
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Written by Dave Astels for Adafruit Industries
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Copyright (c) 2018 Adafruit Industries
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Licensed under the MIT license.
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All text above must be included in any redistribution.
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"""
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import math
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import array
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import board
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import audioio
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import audiocore
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import shapes
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def length(frequency):
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return int(32000 / frequency)
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class Generator:
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sample = None
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dac = None
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shape = None
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frequency = None
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def __init__(self):
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self.dac = audioio.AudioOut(board.A0)
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def reallocate(self, frequency):
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self.sample = array.array("h", [0] * length(frequency))
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def make_sine(self):
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l = len(self.sample)
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for i in range(l):
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self.sample[i] = min(2 ** 15 - 1, int(math.sin(math.pi * 2 * i / l) * (2 ** 15)))
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def make_square(self):
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l = len(self.sample)
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half_l = l // 2
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for i in range(l):
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if i < half_l:
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self.sample[i] = -1 * ((2 ** 15) - 1)
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else:
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self.sample[i] = (2 ** 15) - 1
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def make_triangle(self):
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l = len(self.sample)
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half_l = l // 2
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s = 0
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for i in range(l):
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if i <= half_l:
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s = int((i / half_l) * (2 ** 16)) - (2 ** 15)
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else:
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s = int((1 - ((i - half_l) / half_l)) * (2 ** 16)) - (2 ** 15)
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self.sample[i] = min(2 ** 15 -1, s)
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def make_sawtooth(self):
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l = len(self.sample)
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for i in range(l):
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self.sample[i] = int((i / l) * (2 ** 16)) - (2 ** 15)
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def update(self, shape, frequency):
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if shape == self.shape and frequency == self.frequency:
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return
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if frequency != self.frequency:
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self.reallocate(frequency)
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self.frequency = frequency
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self.shape = shape
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if shape == shapes.SINE:
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self.make_sine()
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elif shape == shapes.SQUARE:
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self.make_square()
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elif shape == shapes.TRIANGLE:
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self.make_triangle()
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elif shape == shapes.SAWTOOTH:
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self.make_sawtooth()
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self.dac.stop()
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self.dac.play(audiocore.RawSample(self.sample, channel_count=1, sample_rate=64000), loop=True)
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