Below is CircuitPython code that works similarly (though not exactly the same) as the Arduino sketch shown on a prior page. To use this, plug the GEMMA M0 into USB…it should show up on your computer as a small flash drive…then edit the file “main.py” with your text editor of choice. Select and copy the code below and paste it into that file, entirely replacing its contents (don’t mix it in with lingering bits of old code). When you save the file, the code should start running almost immediately (if not, see notes at the bottom of this page).
If GEMMA M0 doesn’t show up as a drive, follow the GEMMA M0 guide link above to prepare the board for CircuitPython.
# SPDX-FileCopyrightText: 2017 Mikey Sklar for Adafruit Industries
#
# SPDX-License-Identifier: MIT
# Close Encounters Hat with 10 NeoPixels
# ported from Leslie Birch's Arduino to CircuitPython
#
# Photocell voltage divider center wire to GPIO #2 (analog 1)
# and output tone to GPIO #0 (digital 0)
import time
import analogio
import board
import neopixel
import simpleio
# Initialize input/output pins
photocell_pin = board.A1 # cds photocell connected to this ANALOG pin
speaker_pin = board.D0 # speaker is connected to this DIGITAL pin
pixpin = board.D1 # pin where NeoPixels are connected
numpix = 10 # number of neopixels`
darkness_min = (2 ** 16 / 2) # more dark than light > 32k out of 64k
photocell = analogio.AnalogIn(photocell_pin)
strip = neopixel.NeoPixel(pixpin, numpix, brightness=.4)
# this section is Close Encounters Sounds
toned = 294
tonee = 330
tonec = 262
toneC = 130
toneg = 392
def alien():
strip[8] = (255, 255, 0) # yellow front
strip[3] = (255, 255, 0) # yellow back
simpleio.tone(speaker_pin, toned, 1) # play tone for 1 second
time.sleep(.025)
strip[8] = (0, 0, 0) # clear front
strip[3] = (0, 0, 0) # clear back
time.sleep(.025)
strip[7] = (255, 0, 255) # pink front
strip[2] = (255, 0, 255) # pink back
simpleio.tone(speaker_pin, tonee, 1) # play tone for 1 second
time.sleep(.025)
strip[7] = (0, 0, 0) # clear front
strip[2] = (0, 0, 0) # clear back
time.sleep(.025)
strip[4] = (128, 255, 0) # green front
strip[9] = (128, 255, 0) # green back
simpleio.tone(speaker_pin, tonec, 1) # play tone for 1 second
time.sleep(.025)
strip[4] = (0, 0, 0) # clear front
strip[9] = (0, 0, 0) # clear back
time.sleep(.025)
strip[5] = (0, 0, 255) # blue front
strip[0] = (0, 0, 255) # blue back
simpleio.tone(speaker_pin, toneC, 1) # play tone for 1 second
time.sleep(.075)
strip[5] = (0, 0, 0) # clear front
strip[0] = (0, 0, 0) # clear back
time.sleep(.1)
strip[6] = (255, 0, 0) # red front
strip[1] = (255, 0, 0) # red back
simpleio.tone(speaker_pin, toneg, 1) # play tone for 1 second
time.sleep(.1)
strip[6] = (0, 0, 0) # clear front
strip[1] = (0, 0, 0) # clear back
time.sleep(.1)
# Loop forever...
while True:
# turn lights and audio on when dark
# (less than 50% light on analog pin)
if photocell.value > darkness_min:
alien() # close Encounters Loop
This code requires the neopixel.mpy and simpleio.mpy libraries. A factory-fresh board will have neopixel.py installed. If you’ve just reloaded the board with CircuitPython, create the “lib” directory and obtain neopixel.mpy and simpleio.mpy from the latest Adafruit_CircuitPython_Bundle.
Page last edited January 22, 2025
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