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 “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.
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.
# SPDX-FileCopyrightText: 2017 Limor Fried for Adafruit Industries
#
# SPDX-License-Identifier: MIT
import time
import board
import digitalio
import neopixel
numpix = 8 # Number of NeoPixels
ledpin = board.D1 # Digital pin # where NeoPixels are connected
sensorpin = board.D2 # Digital pin # where light sensor is connected
strip = neopixel.NeoPixel(ledpin, numpix, brightness=1.0)
# Enable internal pullup resistor on sensor pin
pin = digitalio.DigitalInOut(sensorpin)
pin.direction = digitalio.Direction.INPUT
pin.pull = digitalio.Pull.UP
while True: # Loop forever...
# LDR is being used as a digital (binary) sensor. It must be
# completely dark to turn it off, a finger may not be opaque enough!
if pin.value:
color = (0, 0, 0) # Off
else:
color = (255, 0, 255) # Purple
for i in range(numpix): # For each pixel...
strip[i] = color # Set to 'color'
strip.write() # Push data to pixels
time.sleep(0.05) # Pause 50 ms
time.sleep(0.002) # Pause 2 ms
Page last edited January 22, 2025
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