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README.md

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+### Spectroshaker
+
+This code for [Adafruit Circuit Playgroud Bluefruit](https://learn.adafruit.com/adafruit-circuit-playground-bluefruit)
+makes the RGB LEDs around it behave in one of two modes (determined by the state of the slider switch):
+
+* Spectrogram mode: LEDs are affected by low/mid/high levels of mic input (i.e. respond to music)
+* Shaker mode: LEDs are affected by x/y/z acceleration (i.e. respond to dancing)
+
+[video](https://www.zzzen.com/kraftz/2021-11-19-spectroshaker.webm)
+
+#### Note
+
+`lib/teaandtechtime_fft.py` comes from the [no-itertools fork](https://github.com/thedod/CircuitPython_FFT/tree/no-itertools) of Thomas Schucker's `CircuitPython_FFT`.
+It needs to be under the bluefruit's `lib/` folder.

code.py

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+"""
+Spectroshaker by The Dod:
+Adafruit CircuitPlayground Bluefruit dual-mode "bling"
+(selectable via the slider switch).
+The RGB levels of neopixels around the circuit indicate:
+- Low/Mid/High sound levels (spectrogram mode)
+- X/Y/Z acceleration (shaker mode)
+TO BE CONTINUED ...
+"""
+import math
+import time
+from adafruit_circuitplayground import cp
+from teaandtechtime_fft import spectrogram
+
+NUM_PIXELS = 10
+# Like a clock, with connectors at 12 (USB) and 6 (power)
+LED_ANGLES = [
+    i*math.pi/6.0
+    for i in [11, 10, 9, 8, 7, 5, 4, 3, 2, 1]]
+
+minx = miny = minz = -5.0
+maxx = maxy = maxz = 5.0
+
+fft_size = 8 # power of 2
+samples = [0.0+0.0j]*fft_size
+MAX_2FREQ = 10.0 # After testing this a bit in the wild
+
+cp.pixels.brightness = 0.1
+
+def angles2level(led, val):
+    led_angle = LED_ANGLES[led]
+    val_angle = val * 2.0 * math.pi
+    angle = led_angle - val_angle
+    while angle>2*math.pi:
+        angle -= 2*math.pi
+    # the pow() makes sin() values sharper
+    return int(255*pow(math.sin(angle/2), 4))
+
+while True:
+    if cp.button_a:
+        cp.pixels.brightness = max(0.05, cp.pixels.brightness*0.9)
+    elif cp.button_b:
+        cp.pixels.brightness = min(0.95, 1.0-(1.0-cp.pixels.brightness)*0.9)
+
+    samples.pop(0)
+    samples.append(cp.sound_level+0.0j)
+    x, y, z = cp.acceleration
+    if x<minx: minx = x
+    if y<miny: miny = y
+    if z<minz: minz = z
+    if x>maxx: maxx = x
+    if y>maxy: maxy = y
+    if z>maxx: maxz = z
+    if cp.switch: # accelerometer mode
+        vals = (
+            (x-minx)/(maxx-minx),
+            (y-miny)/(maxy-miny),
+            (z-minz)/(maxz-minz))
+    else: # spectrogram mode
+        raw_freqs = spectrogram(samples)
+        pairs = [raw_freqs[i]+raw_freqs[i+1] for i in range(fft_size//2)]
+        vals = [min(1.0, abs(x/MAX_2FREQ)) for x in pairs[:3]]
+    for i in range(NUM_PIXELS):
+        cp.pixels[i] = (
+            angles2level(i, vals[0]),
+            angles2level(i, vals[1]),
+            angles2level(i, vals[2]))
+    time.sleep(0.01)

lib/teaandtechtime_fft.py

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+# The MIT License (MIT)
+#
+# Copyright (c) 2019 Tom Schucker for Tea and Tech Time
+#
+# 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.
+"""
+`teaandtechtime_fft`
+================================================================================
+
+CircuitPython FFT Library
+
+* Author(s): Tom Schucker
+
+Implementation Notes
+---------------------
+This variant comes from @thedod's `no-itertools` fork:
+https://github.com/thedod/CircuitPython_FFT/tree/no-itertools
+
+**Hardware:**
+
+**Software and Dependencies:**
+
+* Adafruit CircuitPython firmware for the supported boards:
+  https://github.com/adafruit/circuitpython/releases
+
+"""
+
+# imports
+from math import pi, sin, cos, sqrt, pow, log
+import array
+
+__version__ = "0.0.0-auto.0"
+__repo__ = "https://github.com/tschucker/Teaandtechtime_CircuitPython_FFT.git"
+
+#Computes the complex fft of the input array needs to be power of 2 length to work.
+def fft(x):
+    N = len(x)
+    if N <= 1: return x
+    even = fft([x[i] for i in range(0, N, 2)])
+    odd =  fft([x[i] for i in range(1, N, 2)])
+    T = [cos(2*pi*k/N)*odd[k].real+sin(2*pi*k/N)*odd[k].imag + (cos(2*pi*k/N)*odd[k].imag-sin(2*pi*k/N)*odd[k].real)*1j for k in range(N//2)]
+    return [even[k].real + T[k].real + (even[k].imag + T[k].imag)*1j for k in range(N//2)] + \
+           [even[k].real - T[k].real + (even[k].imag - T[k].imag)*1j for k in range(N//2)]
+
+#Computes the complex inverse fft of the input array needs to be power of 2 length to work
+#not the most efficiant but uses the same fft code.
+def ifft(x):
+    fft_len = float(len(x))
+    x_swap = []
+    for s in x:
+        x_swap.append(s.imag + s.real*1j)
+    temp = fft(x_swap)
+    temp_swap = []
+    for s in temp:
+        temp_swap.append((s.imag/fft_len) + (s.real/fft_len)*1j)
+    return temp_swap
+
+#Computes the double sided spectrogram of the input array needs to be a power of 2 to work
+def spectrogram(x):
+    freq = fft(x)
+    temp_list = []
+    for f in freq:
+        abs_val = abs(f)
+        if  abs_val != 0.0:
+            temp_list.append(int(log(abs_val)))
+        else:
+            temp_list.append(0)
+    return temp_list
+
+