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 to the Arduino sketch shown on theprior 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 Phillip Burgess for Adafruit Industries # # SPDX-License-Identifier: MIT import time import board import neopixel try: import urandom as random # for v1.0 API support except ImportError: import random numpix = 36 # Number of NeoPixels pixpin = board.D1 # Pin where NeoPixels are connected strip = neopixel.NeoPixel(pixpin, numpix, brightness=1.0) mode = 0 # Current animation effect offset = 0 # Position of spinner animation color = [160, 0, 160] # RGB color - purple prevtime = time.monotonic() # Time of last animation mode switch while True: # Loop forever... if mode == 0: # Random sparkles - lights just one LED at a time i = random.randint(0, numpix - 1) # Choose random pixel strip[i] = color # Set it to current color strip.write() # Refresh LED states # Set same pixel to "off" color now but DON'T refresh... # it stays on for now...bot this and the next random # pixel will be refreshed on the next pass. strip[i] = [0, 0, 0] time.sleep(0.008) # 8 millisecond delay elif mode == 1: # Spinny wheel (4 LEDs on at a time) for i in range(numpix): # For each LED... if ((offset + i) & 7) < 2: # 2 pixels out of 8... strip[i] = color # are set to current color else: strip[i] = [0, 0, 0] # other pixels are off strip.write() # Refresh LED states time.sleep(0.08) # 80 millisecond delay offset += 1 # Shift animation by 1 pixel on next frame if offset >= 8: offset = 0 # Additional animation modes could be added here! t = time.monotonic() # Current time in seconds if (t - prevtime) >= 8: # Every 8 seconds... mode += 1 # Advance to next mode if mode > 1: # End of modes? mode = 0 # Start over from beginning strip.fill([0, 0, 0]) # Turn off all pixels prevtime = t # Record time of last mode change
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.
Page last edited January 22, 2025
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