71 lines
2.4 KiB
Python
71 lines
2.4 KiB
Python
#!/usr/bin/python3
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# Persistence-of-vision (POV) example for Adafruit DotStar RGB LED strip.
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# Loads image, displays column-at-a-time on LEDs at very high speed,
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# suitable for naked-eye illusions.
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# See dotstar_simpletest.py for a much simpler example script.
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# See dotstar_image_paint.py for a slightly simpler light painting example.
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# This code accesses some elements of the dotstar object directly rather
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# than through function calls or setters/getters...this is poor form as it
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# could break easily with future library changes, but is the only way right
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# now to do the POV as quickly as possible.
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# May require installing separate libraries.
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import board
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from PIL import Image
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import adafruit_dotstar as dotstar
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NUMPIXELS = 30 # Length of DotStar strip
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FILENAME = "hello.png" # Image file to load
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ORDER = dotstar.BGR # Change to GBR for older DotStar strips
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# First two arguments in strip declaration identify the clock and data pins
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# (here we're using the hardware SPI pins).
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DOTS = dotstar.DotStar(
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board.SCK,
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board.MOSI,
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NUMPIXELS,
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auto_write=False,
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brightness=1.0,
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pixel_order=ORDER,
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)
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# Load image in RGB format and get dimensions:
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print("Loading...")
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IMG = Image.open(FILENAME).convert("RGB")
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PIXELS = IMG.load()
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WIDTH = IMG.size[0]
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HEIGHT = IMG.size[1]
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print("%dx%d pixels" % IMG.size)
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if HEIGHT > NUMPIXELS:
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HEIGHT = NUMPIXELS
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# Calculate gamma correction table, makes mid-range colors look 'right':
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GAMMA = bytearray(256)
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brightness = 0.25
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for i in range(256):
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GAMMA[i] = int(pow(float(i) / 255.0, 2.7) * brightness * 255.0 + 0.5)
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# Allocate list of lists, one for each column of image.
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print("Allocating...")
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COLUMN = [0 for x in range(WIDTH)]
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for x in range(WIDTH):
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COLUMN[x] = [[0, 0, 0, 0] for _ in range(HEIGHT)]
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# Convert entire RGB image into columnxrow 2D list.
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print("Converting...")
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for x in range(WIDTH): # For each column of image
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for y in range(HEIGHT): # For each pixel in column
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value = PIXELS[x, y] # Read RGB pixel in image
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COLUMN[x][y][0] = GAMMA[value[0]] # Gamma-corrected R
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COLUMN[x][y][1] = GAMMA[value[1]] # Gamma-corrected G
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COLUMN[x][y][2] = GAMMA[value[2]] # Gamma-corrected B
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COLUMN[x][y][3] = 1.0 # Brightness
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print("Displaying...")
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while True: # Loop forever
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for x in range(WIDTH): # For each column of image...
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DOTS[0 : DOTS.n] = COLUMN[x] # Copy column to DotStar buffer
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DOTS.show() # Send data to strip
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