cpxtest.py

   1 # SPDX-FileCopyrightText: 2017 Dan Halbert for Adafruit Industries
   2 # SPDX-FileCopyrightText: 2017 Tony DiCola for Adafruit Industries
   3 # SPDX-FileCopyrightText: 2017 Kattni Rembor for Adafruit Industries
   4 #
   5 # SPDX-License-Identifier: MIT
   6
   7 # The MIT License (MIT)
   8 #
   9 # Copyright (c) 2017 Dan Halbert for Adafruit Industries
  10 # Copyright (c) 2017 Kattni Rembor, Tony DiCola for Adafruit Industries
  11 #
  12 # Permission is hereby granted, free of charge, to any person obtaining a copy
  13 # of this software and associated documentation files (the "Software"), to deal
  14 # in the Software without restriction, including without limitation the rights
  15 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  16 # copies of the Software, and to permit persons to whom the Software is
  17 # furnished to do so, subject to the following conditions:
  18 #
  19 # The above copyright notice and this permission notice shall be included in
  20 # all copies or substantial portions of the Software.
  21 #
  22 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  25 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  26 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  27 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  28 # THE SOFTWARE.
  29
  30 # Circuit Playground Sound Meter
  31
  32 import array
  33 import math
  34 import audiobusio
  35 import board
  36 import neopixel
  37
  38 # Color of the peak pixel.
  39 PEAK_COLOR = (100, 0, 255)
  40 # Number of total pixels - 10 build into Circuit Playground
  41 NUM_PIXELS = 10
  42
  43 # Exponential scaling factor.
  44 # Should probably be in range -10 .. 10 to be reasonable.
  45 CURVE =4
  46 SCALE_EXPONENT = math.pow(10, CURVE * -0.1)
  47
  48 # Number of samples to read at once.
  49 NUM_SAMPLES = 160
  50
  51
  52 # Restrict value to be between floor and ceiling.
  53 def constrain(value, floor, ceiling):
  54     return max(floor, min(value, ceiling))
  55
  56
  57 # Scale input_value between output_min and output_max, exponentially.
  58 def log_scale(input_value, input_min, input_max, output_min, output_max):
  59     normalized_input_value = (input_value - input_min) / \
  60                              (input_max - input_min)
  61     return output_min + \
  62         math.pow(normalized_input_value, SCALE_EXPONENT) \
  63         * (output_max - output_min)
  64
  65
  66 # Remove DC bias before computing RMS.
  67 def normalized_rms(values):
  68     minbuf = int(mean(values))
  69     samples_sum = sum(
  70         float(sample - minbuf) * (sample - minbuf)
  71         for sample in values
  72     )
  73
  74     return math.sqrt(samples_sum / len(values))
  75
  76
  77 def mean(values):
  78     return sum(values) / len(values)
  79
  80
  81 def volume_color(volume):
  82     return 200, volume * (255 // NUM_PIXELS), 0
  83
  84
  85 # Main program
  86
  87 # Set up NeoPixels and turn them all off.
  88 pixels = neopixel.NeoPixel(board.NEOPIXEL, NUM_PIXELS, brightness=0.1, auto_write=False)
  89 pixels.fill(0)
  90 pixels.show()
  91
  92 mic = audiobusio.PDMIn(board.MICROPHONE_CLOCK, board.MICROPHONE_DATA,
  93                        sample_rate=16000, bit_depth=16)
  94
  95 # Record an initial sample to calibrate. Assume it's quiet when we start.
  96 samples = array.array('H', [0] * NUM_SAMPLES)
  97 mic.record(samples, len(samples))
  98 # Set lowest level to expect, plus a little.
  99 input_floor = normalized_rms(samples) + 10
 100 # OR: used a fixed floor
 101 # input_floor = 50
 102
 103 # You might want to print the input_floor to help adjust other values.
 104 # print(input_floor)
 105
 106 # Corresponds to sensitivity: lower means more pixels light up with lower sound
 107 # Adjust this as you see fit.
 108 input_ceiling = input_floor + 500
 109
 110 peak = 0
 111 while True:
 112     mic.record(samples, len(samples))
 113     magnitude = normalized_rms(samples)
 114     # You might want to print this to see the values.
 115     # print(magnitude)
 116
 117     # Compute scaled logarithmic reading in the range 0 to NUM_PIXELS
 118     c = log_scale(constrain(magnitude, input_floor, input_ceiling),
 119                   input_floor, input_ceiling, 0, NUM_PIXELS)
 120
 121     # Light up pixels that are below the scaled and interpolated magnitude.
 122     pixels.fill(0)
 123     for i in range(NUM_PIXELS):
 124         if i < c:
 125             pixels[i] = volume_color(i)
 126         # Light up the peak pixel and animate it slowly dropping.
 127         if c >= peak:
 128             peak = min(c, NUM_PIXELS - 1)
 129         elif peak > 0:
 130             peak = peak - 1
 131         if peak > 0:
 132             pixels[int(peak)] = PEAK_COLOR
 133     pixels.show()