Gauges Just in time for Halloween 🎃, I made a ghost decoration that uses an Adafruit Circuit Playground Express.

The ceramic ghost is from a home decoration shop. I have put a little piece of sandwich paper inside, so the LED light can be seen through the ghost's mouth and eyes.

The MicroPython source shows a candle light effect. For the flame, a mystic cyan color is used, so the ghost appears really spooky. 👻

If you copy `.wav` files to the Circuit Playground, a random sound effect is played from time to time. I found nice free sound effects on soundbible.com that surely give everyone the chills. The sound files should be converted to mono and 16 kHz sampling rate, so they fit into the tiny Playground Express memory. The sound effects can be muted using the switch on the Playground, if they should become too annoying. 😉

This is the `code.py` file that is to be copied to the Circuit Playground. The candle simulation was inspired by an example at AdaFruit. I made the candle color configurable and added the sound effects.

``````import math
import os
import random
import time

import audioio
import board
import digitalio

CANDLE_COLOR = (0x00, 0xC0, 0xFF)
MIN_BRIGHTNESS = 64
MAX_BRIGHTNESS = 191

EFFECT_COLOR = (0xFF, 0x00, 0x00)
STEPS_BEFORE_EFFECT = 100

def split(first, second, offset):
if offset != 0:
mid = ((first + second + 1) / 2 + random.randint(-offset, offset))
offset = int(offset / 2)
split(first, mid, offset)
split(mid, second, offset)
else:
level = math.pow(first / 255.0, 2.7) * 255.0 + 0.5
cpx.pixels.fill((
min(255, int(level * CANDLE_COLOR / 256)),
min(255, int(level * CANDLE_COLOR / 256)),
min(255, int(level * CANDLE_COLOR / 256))
))
cpx.pixels.show()

def colorShift(start, end, time):
for i in range(1, time):
j = time - i
cpx.pixels.fill((
min(255, int((start * j + end * i) / time)),
min(255, int((start * j + end * i) / time)),
min(255, int((start * j + end * i) / time))
))
cpx.pixels.show()

cpx.pixels.brightness = 0.4
cpx.pixels.auto_write = False
cpx.pixels.fill((0, 0, 0))
cpx.pixels.show()

sounds = [f for f in os.listdir() if f.endswith('.wav')]

count = 0
prev = (MAX_BRIGHTNESS + MIN_BRIGHTNESS) / 2

while True:
lvl = random.randint(MIN_BRIGHTNESS, MAX_BRIGHTNESS)
split(prev, lvl, 32)
prev = lvl
count += 1
if (count > STEPS_BEFORE_EFFECT):
count = 0
if cpx.switch:
oldcolor = cpx.pixels
cpx.pixels.fill(EFFECT_COLOR)
cpx.pixels.show()
cpx.play_file(random.choice(sounds))
colorShift(EFFECT_COLOR, oldcolor, 10)
``````