Initial version of CircuitPlaygroundExpress_SoundMeter.py for testing

Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_SoundMeter.py

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+# The MIT License (MIT)
+#
+# Copyright (c) 2017 Dan Halbert for Adafruit Industries
+# Copyright (c) 2017 Kattni Rembor, Tony DiCola for Adafruit Industries
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+import array
+import audiobusio
+import board
+import math
+import neopixel
+
+# Exponential scaling factor.
+# Should probably be in range -10 .. 10 to be reasonable.
+CURVE = 2
+SCALE_EXPONENT = math.pow(10, CURVE*-0.1)
+
+PEAK_COLOR = (100, 0, 255)
+NUM_PIXELS = 10
+
+# Number of samples to read at once.
+NUM_SAMPLES = 160
+
+# Restrict value to be between floor and ceiling.
+def constrain(value, floor, ceiling):
+    return max(floor, min(value, ceiling))
+
+# Scale input_value to be between output_min and output_max, in an exponential way.
+def log_scale(input_value, input_min, input_max, output_min, output_max):
+    normalized_input_value = (input_value - input_min) / (input_max - input_min)
+    return output_min + math.pow(normalized_input_value, SCALE_EXPONENT) * (output_max - output_min)
+
+# Remove DC bias before computing RMS.
+def normalized_rms(values):
+    minbuf = int(mean(values))
+    return math.sqrt(sum(float((sample-minbuf)*(sample-minbuf)) for sample in values)/len(values))
+
+def mean(values):
+    return (sum(values) / len(values))
+
+def volume_color(i):
+    return (200, i*(255//NUM_PIXELS), 0)
+
+# Main program
+
+# Set up NeoPixels and turn them all off.
+pixels = neopixel.NeoPixel(board.NEOPIXEL, NUM_PIXELS, brightness=0.1, auto_write=False)
+pixels.fill(0)
+pixels.show()
+
+mic = audiobusio.PDMIn(board.MICROPHONE_CLOCK, board.MICROPHONE_DATA, frequency=16000, bit_depth=16)
+# Record an initial sample to calibrate. Assume it's quiet when we start.
+samples = array.array('H', [0] * NUM_SAMPLES)
+mic.record(samples, len(samples))
+# Set lowest level to expect, plus a little.
+input_floor = normalized_rms(samples) + 10
+# OR: used a fixed floor
+# input_floor = 50
+
+# You might want to print the input_floor to help adjust other values.
+# print(input_floor)
+
+# Corresponds to sensitivity: lower means more pixels light up with lower sound
+# Adjust this as you see fit.
+input_ceiling = input_floor + 500
+
+peak = 0
+while True:
+    mic.record(samples, len(samples))
+    magnitude = normalized_rms(samples)
+    # You might want to print this to see the values.
+    # print(magnitude)
+
+    # Compute scaled logarithmic reading in the range 0 to NUM_PIXELS
+    c = log_scale(constrain(magnitude, input_floor, input_ceiling), input_floor, input_ceiling, 0, NUM_PIXELS)
+
+    # Light up pixels that are below the scaled and interpolated magnitude.
+    pixels.fill(0)
+    for i in range(NUM_PIXELS):
+        if i < c:
+            pixels[i] = volume_color(i)
+        # Light up the peak pixel and animate it slowly dropping.
+        if c >= peak:
+            peak = min(c, NUM_PIXELS-1)
+        elif peak > 0:
+            peak = peak - 1
+        if peak > 0:
+            pixels[int(peak)] = PEAK_COLOR
+    pixels.show()