Audio level meter with Circuit Playground Express

code.py

import array
import math
import time
import neopixel
import audiobusio
import board

def avg(values):
    return sum(values) / len(values)

def normalized_rms(values):
    avg_value = int(avg(values))
    sum_samples = sum(float(sample - avg_value) * (sample - avg_value) for sample in values)
    return math.sqrt(sum_samples / len(values))

pixels = neopixel.NeoPixel(board.NEOPIXEL, 10, brightness=0.1, auto_write=False)

mic = audiobusio.PDMIn(board.MICROPHONE_CLOCK, board.MICROPHONE_DATA, bit_depth=16)
samples = array.array('H', [0] * 192)
mic.record(samples, len(samples))

while True:
    mic.record(samples, len(samples))
    magnitude = normalized_rms(samples)

    pixels.fill((0, 0, 0))
    pixels[0] = pixels[9] = (0, 128, 0)
    if magnitude > 50:
        pixels[1] = pixels[8] = (64, 128, 0)
    if magnitude > 100:
        pixels[2] = pixels[7] = (128, 64, 0)
    if magnitude > 200:
        pixels[3] = pixels[6] = (128, 32, 0)
    if magnitude > 400:
        pixels[4] = pixels[5] = (128, 0, 0)
    pixels.show()

    time.sleep(0.1)