CircuitPython Code

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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.

These directions are specific to the “M0” GEMMA board. The GEMMA v2 with an 8-bit AVR microcontroller doesn’t run CircuitPython…for those boards, use the Arduino sketch on the “Arduino code” page of this 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.

This code requires two additional libraries be installed:

  1. adafruit_circuitpython_ht16k33
  2. adafruit_bus_device

If you’ve just reloaded the board with CircuitPython, create the “lib” directory and then download the Adafruit CircuitPython Bundle.

Due to pin differences on the Gemma M0 versus the Gemma v2 we are using D1 as the optional touch based reset. The onboard Gemma M0 switch and reset button will also reset the animation.
Download Project Bundle
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# SPDX-FileCopyrightText: 2014 Phil Burgess for Adafruit Industries
# SPDX-FileCopyrightText: 2018 Phil Burgess for Adafruit Industries
#
# SPDX-License-Identifier: MIT
#
# Trinket/Gemma + LED matrix backpack jewelry.  Plays animated
# sequence on LED matrix. Press reset button to display again.

import time
import adafruit_ht16k33.matrix
import board
import busio as io
import touchio

touch = touchio.TouchIn(board.D1)

i2c = io.I2C(board.SCL, board.SDA)
matrix = adafruit_ht16k33.matrix.Matrix8x8(i2c)

# pixels initializers
x_pix = y_pix = 8
x = y = 0
matrix.fill(0)
matrix.show()

# seconds to pause between frames
frame_delay = [.25, .25, .25, .25, .25, .25, .25, .25, .25, .25]

# counter for animation frames
frame_count = 0

# repeat entire animation multiple times
reps = 255
rep_count = reps

# animation bitmaps
animation = [
    # frame 1
    [[1, 1, 1, 1, 1, 1, 1, 1], [1, 0, 0, 1, 1, 0, 0, 1],
     [1, 0, 0, 1, 1, 0, 0, 1], [1, 1, 1, 1, 1, 1, 1, 1],
     [1, 0, 0, 0, 0, 0, 0, 1], [1, 1, 0, 0, 0, 0, 1, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1]],
    # frame 2
    [[1, 1, 1, 1, 1, 1, 1, 1], [1, 0, 0, 1, 1, 0, 0, 1],
     [1, 0, 0, 1, 1, 0, 0, 1], [1, 1, 1, 1, 1, 1, 1, 1],
     [1, 0, 1, 1, 1, 1, 0, 1], [1, 0, 1, 1, 1, 1, 0, 1],
     [1, 1, 0, 0, 0, 0, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1]],
    # frame 3
    [[1, 1, 1, 1, 1, 1, 1, 1], [1, 0, 0, 1, 1, 0, 0, 1],
     [1, 0, 0, 1, 1, 0, 0, 1], [1, 1, 1, 1, 1, 1, 1, 1],
     [1, 0, 0, 0, 0, 0, 0, 1], [1, 1, 0, 0, 0, 0, 1, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1]],
    # frame 4
    [[1, 1, 1, 1, 1, 1, 1, 1], [1, 0, 0, 1, 1, 0, 0, 1],
     [1, 0, 0, 1, 1, 0, 0, 1], [1, 1, 1, 1, 1, 1, 1, 1],
     [1, 0, 1, 1, 1, 1, 0, 1], [1, 0, 1, 1, 1, 1, 0, 1],
     [1, 1, 0, 0, 0, 0, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1]],
    # frame 5
    [[1, 1, 1, 1, 1, 1, 1, 1], [1, 0, 0, 1, 1, 0, 0, 1],
     [1, 0, 0, 1, 1, 0, 0, 1], [1, 1, 1, 1, 1, 1, 1, 1],
     [1, 1, 1, 1, 1, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1],
     [1, 0, 0, 0, 0, 0, 0, 1], [1, 1, 1, 1, 1, 1, 1, 1]],
    # frame 6
    [[1, 1, 1, 1, 1, 1, 1, 1], [1, 0, 0, 1, 1, 0, 0, 1],
     [1, 0, 0, 1, 1, 0, 0, 1], [1, 1, 1, 1, 1, 1, 1, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 0, 1, 1, 0, 1, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1]],
    # frame 7
    [[1, 1, 1, 1, 1, 1, 1, 1], [1, 0, 1, 1, 1, 1, 0, 1],
     [0, 0, 0, 1, 1, 0, 0, 0], [1, 0, 1, 1, 1, 1, 0, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 0, 1, 1, 0, 1, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1]],
    # frame 8
    [[1, 1, 1, 1, 1, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1],
     [0, 0, 0, 1, 1, 0, 0, 0], [1, 1, 1, 1, 1, 1, 1, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 0, 1, 1, 0, 1, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1]],
    # frame 9
    [[1, 1, 1, 1, 1, 1, 1, 1], [1, 0, 1, 1, 1, 1, 0, 1],
     [0, 0, 0, 1, 1, 0, 0, 0], [1, 0, 1, 1, 1, 1, 0, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 0, 1, 1, 0, 1, 1],
     [1, 1, 1, 0, 0, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1]],
]

#
# run until we are out of animation frames
# use Gemma's built-in reset button or switch to restart
#
# populate matrix
while True:

    if frame_count < len(animation) and rep_count >= 0:
        for x in range(x_pix):
            for y in range(y_pix):
                matrix.pixel(x, y, animation[frame_count][x][y])

        # next animation frame
        frame_count += 1

        # show animation
        matrix.show()

        # pause for effect
        time.sleep(frame_delay[frame_count])

    else:

        matrix.fill(0)
        matrix.show()
        time.sleep(.1)

        # track repitions
        rep_count -= 1

        # play it again
        frame_count = 0

        # A0/D1 pin has been touched
        # reset animation
        if touch.value:
            frame_count = 0
            rep_count = reps
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 Arduino Code Assembling Circuit  

This guide was first published on Feb 20, 2014. It was last updated on Feb 20, 2014.

This page (CircuitPython Code) was last updated on Jun 05, 2023.

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