103 lines
4.3 KiB
Python
Executable file
103 lines
4.3 KiB
Python
Executable file
# SPDX-FileCopyrightText: 2022 Phillip Burgess for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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"""
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CircuitPython random blinkenlights for Little Connection Machine. For
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Raspberry Pi Pico RP2040, but could be adapted to other CircuitPython-
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capable boards with two or more I2C buses. Requires adafruit_bus_device
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and adafruit_is31fl3731 libraries.
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This code plays dirty pool to get fast matrix updates and is NOT good code
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to learn from, and might fail to work with future versions of the IS31FL3731
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library. But doing things The Polite Way wasn't fast enough. Explained as
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we go...
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"""
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# pylint: disable=import-error
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import random
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import board
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import busio
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from adafruit_is31fl3731.matrix import Matrix as Display
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BRIGHTNESS = 40 # CONFIGURABLE: LED brightness, 0 (off) to 255 (max)
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PERCENT = 33 # CONFIGURABLE: amount of 'on' LEDs, 0 (none) to 100 (all)
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# This code was originally written for the Raspberry Pi Pico, but should be
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# portable to any CircuitPython-capable board WITH TWO OR MORE I2C BUSES.
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# IS31FL3731 can have one of four addresses, so to run eight of them we
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# need *two* I2C buses, and not all boards can provide that. Here's where
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# you'd define the pin numbers for a board...
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I2C1_SDA = board.GP4 # First I2C bus
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I2C1_SCL = board.GP5
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I2C2_SDA = board.GP26 # Second I2C bus
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I2C2_SCL = board.GP27
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# pylint: disable=too-few-public-methods
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class FakePILImage:
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"""Minimal class meant to simulate a small subset of a Python PIL image,
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so we can pass it to the IS31FL3731 image() function later. THIS IS THE
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DIRTY POOL PART OF THE CODE, because CircuitPython doesn't have PIL,
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it's too much to handle. That image() function is normally meant for
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robust "desktop" Python, using the Blinka package...but it's still
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present (but normally goes unused) in CircuitPython. Having worked with
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that library source, I know exactly what object members its looking for,
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and can fake a minimal set here...BUT THIS MAY BREAK IF THE LIBRARY OR
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PIL CHANGES!"""
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def __init__(self):
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self.mode = "L" # Grayscale mode in PIL
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self.size = (16, 9) # 16x9 pixels
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self.pixels = bytearray(16 * 9) # Pixel buffer
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def tobytes(self):
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"""IS31 lib requests image pixels this way, more dirty pool."""
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return self.pixels
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# Okay, back to business...
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# Instantiate the two I2C buses. 400 KHz bus speed is recommended.
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# Default 100 KHz is a bit slow, and 1 MHz has occasional glitches.
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I2C = [
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busio.I2C(I2C1_SCL, I2C1_SDA, frequency=400000),
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busio.I2C(I2C2_SCL, I2C2_SDA, frequency=400000),
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]
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# Four matrices on each bus, for a total of eight...
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DISPLAY = [
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Display(I2C[0], address=0x74, frames=(0, 1)), # Upper row
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Display(I2C[0], address=0x75, frames=(0, 1)),
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Display(I2C[0], address=0x76, frames=(0, 1)),
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Display(I2C[0], address=0x77, frames=(0, 1)),
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Display(I2C[1], address=0x74, frames=(0, 1)), # Lower row
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Display(I2C[1], address=0x75, frames=(0, 1)),
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Display(I2C[1], address=0x76, frames=(0, 1)),
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Display(I2C[1], address=0x77, frames=(0, 1)),
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]
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IMAGE = FakePILImage() # Instantiate fake PIL image object
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FRAME_INDEX = 0 # Double-buffering frame index
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while True:
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# Draw to each display's "back" frame buffer
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for disp in DISPLAY:
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for pixel in range(0, 16 * 9): # Randomize each pixel
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IMAGE.pixels[pixel] = BRIGHTNESS if random.randint(1, 100) <= PERCENT else 0
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# Here's the function that we're NOT supposed to call in
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# CircuitPython, but is still present. This writes the pixel
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# data to the display's back buffer. Pass along our "fake" PIL
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# image and it accepts it.
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disp.image(IMAGE, frame=FRAME_INDEX)
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# Then quickly flip all matrix display buffers to FRAME_INDEX
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for disp in DISPLAY:
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disp.frame(FRAME_INDEX, show=True)
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FRAME_INDEX ^= 1 # Swap buffers
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# This is actually the LESS annoying way to get fast updates. Other involved
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# writing IS31 registers directly and accessing intended-as-private methods
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# in the IS31 lib. That's a really bad look. It's pretty simple here because
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# this code is just drawing random dots. Producing a spatially-coherent
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# image would take a lot more work, because matrices are rotated, etc.
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# The PIL+Blinka code for Raspberry Pi easily handles such things, so
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# consider working with that if you need anything more sophisticated.
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