105 lines
3.2 KiB
Python
105 lines
3.2 KiB
Python
# Add a SCD41 sensor breakout to your Stellar Unicorn to make a handy CO2 detector!
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# https://shop.pimoroni.com/products/scd41-co2-sensor-breakout
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# Press A for CO2, B for temperature and C for humidity
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# This example uses a custom tiny font - find 3x5.bitmapfont in /common/fonts
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from stellar import StellarUnicorn
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from picographics import PicoGraphics, DISPLAY_STELLAR_UNICORN as DISPLAY
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import breakout_scd41
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from pimoroni_i2c import PimoroniI2C
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from pimoroni import BREAKOUT_GARDEN_I2C_PINS
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su = StellarUnicorn()
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graphics = PicoGraphics(DISPLAY)
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i2c = PimoroniI2C(**BREAKOUT_GARDEN_I2C_PINS)
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# the range of readings to map to colours
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# https://www.kane.co.uk/knowledge-centre/what-are-safe-levels-of-co-and-co2-in-rooms
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MIN = 400
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MAX = 2000
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# pick what bits of the colour wheel to use (from 0-360°)
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# https://www.cssscript.com/demo/hsv-hsl-color-wheel-picker-reinvented/
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HUE_START = 100 # green
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HUE_END = 0 # red
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# some pen colours to use
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BLACK = graphics.create_pen(0, 0, 0)
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WHITE = graphics.create_pen(255, 255, 255)
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# some other variables to keep track of stuff
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mode = "co2"
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flashy_light = False
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# sets up a handy function we can call to clear the screen
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def clear():
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graphics.set_pen(BLACK)
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graphics.clear()
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# set up
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breakout_scd41.init(i2c)
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breakout_scd41.start()
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graphics.set_font(open("3x5.bitmapfont", "rb").read())
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graphics.set_pen(WHITE)
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graphics.text("WAIT", 0, 0, scale=1)
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su.update(graphics)
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while True:
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if su.is_pressed(StellarUnicorn.SWITCH_A):
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mode = "co2"
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if su.is_pressed(StellarUnicorn.SWITCH_B):
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mode = "temp"
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if su.is_pressed(StellarUnicorn.SWITCH_C):
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mode = "humidity"
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if breakout_scd41.ready():
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clear()
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# read the sensor
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co2, temperature, humidity = breakout_scd41.measure()
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# calculate a colour from the co2 reading
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hue = max(0, HUE_START + ((co2 - MIN) * (HUE_END - HUE_START) / (MAX - MIN)))
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# draw the border and background
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graphics.set_pen(graphics.create_pen_hsv((hue / 360), 1.0, 0.8))
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graphics.clear()
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graphics.set_pen(graphics.create_pen_hsv((hue / 360), 1.0, 0.2))
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graphics.rectangle(1, 1, 14, 14)
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graphics.set_pen(WHITE)
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if mode == "co2":
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# draw the co2 level
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co2_string = str(co2)
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if co2 < 1000:
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graphics.text(f"{co2:.0f}", 2, 2, scale=1, fixed_width=True)
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else:
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graphics.text(f"{co2_string[0]}", 1, 2, scale=1, fixed_width=True)
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graphics.text(f"{co2_string[1]}K", 7, 2, scale=1, fixed_width=True)
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graphics.pixel(5, 6)
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graphics.text("PPM", 3, 9, scale=1)
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if mode == "temp":
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# draw the temperature
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graphics.text("T:", 2, 2, scale=1)
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graphics.text(f"{temperature:.0f}°", 2, 8, scale=1, fixed_width=True)
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if mode == "humidity":
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# draw the temperature
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graphics.text("H:", 2, 2, scale=1)
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graphics.text(f"{humidity:.0f}%", 2, 8, scale=1, fixed_width=True)
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# flash the top right pixel to show the sensor's been read
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if flashy_light is False:
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graphics.pixel(15, 0)
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flashy_light = True
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else:
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flashy_light = False
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su.update(graphics)
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