GEMMA M0 boards can run CircuitPython — a different approach to programming compared to Arduino sketches. In fact, CircuitPython comes factory pre-loaded on GEMMA M0. If you’ve overwritten it with an Arduino sketch, or just want to learn the basics of setting up and using CircuitPython, this is explained in the Adafruit GEMMA M0 guide.
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 “code.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
# NeoPixie Dust Bag
# learn.adafruit.com/neopixel-pixie-dust-bag
import time
import board
import digitalio
import neopixel
try:
import urandom as random # for v1.0 API support
except ImportError:
import random
neo_pin = board.D0 # DIGITAL IO pin for NeoPixel OUTPUT from GEMMA
touch_pin = board.D2 # DIGITAL IO pin for momentary touch sensor to GEMMA
pixel_count = 30 # Number of NeoPixels connected to GEMMA
delay_sec = .010 # delay between blinks, smaller numbers are faster
delay_mult = 8 # Randomization multiplier, delay speed of the effect
# initialize neopixels
pixels = neopixel.NeoPixel(
neo_pin, pixel_count, brightness=.4, auto_write=False)
oldstate = False # counting touch sensor button pushes
showcolor = 0 # color mode for cycling
# initialize external capacitive touch pad (active high)
button = digitalio.DigitalInOut(touch_pin)
button.direction = digitalio.Direction.INPUT
button.pull = digitalio.Pull.UP
while True:
rcolor = 100 # swtich cycles colors, initially GOLD
gcolor = 0
bcolor = 0
if showcolor == 0: # Garden PINK
rcolor = 242
gcolor = 90
bcolor = 255
elif showcolor == 1: # Pixie GOLD
rcolor = 255
gcolor = 222
bcolor = 30
elif showcolor == 2: # Alchemy BLUE
rcolor = 50
gcolor = 255
bcolor = 255
elif showcolor == 3: # Animal ORANGE
rcolor = 255
gcolor = 100
bcolor = 0
elif showcolor == 4: # Tinker GREEN
rcolor = 0
gcolor = 255
bcolor = 40
# sparkling
# select a random pixel
p = random.randint(0, (pixel_count - 2))
# color value from momentary switch
pixels[p] = (rcolor, gcolor, bcolor)
pixels.write()
# delay value randomized to up to delay_mult times longer
time.sleep(delay_sec * random.randint(0, delay_mult))
# set to a dimmed version of the state color
pixels[p] = (int(rcolor / 10), int(gcolor / 10), int(bcolor / 10))
pixels.write()
# set a neighbor pixel to an even dimmer value
pixels[p + 1] = (int(rcolor / 15), int(gcolor / 15), int(bcolor / 15))
pixels.write()
# button check to cycle through color value sets
# get the current button state
newstate = button.value
# Check if state changed from low to high (button/touchpad press).
if newstate and not oldstate:
# cycle to next color
showcolor += 1
# limit the cycle to the 5 colors
if showcolor > 4:
showcolor = 0
# give feedback to the REPL to debug the touch pad
# print("Color:", showcolor)
# Set the last button state to the old state.
oldstate = newstate
This code requires the neopixel.py library. A factory-fresh board will have this already installed. If you’ve just reloaded the board with CircuitPython, create the “lib” directory and then download neopixel.py from Github.
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