kopia lustrzana https://github.com/pimoroni/pimoroni-pico
125 wiersze
3.7 KiB
Python
125 wiersze
3.7 KiB
Python
# Add a SCD41 sensor breakout to your GFX Pack 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 to reset the high/low values.
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import breakout_scd41
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from gfx_pack import SWITCH_A, GfxPack
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gp = GfxPack()
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display = gp.display
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WIDTH, HEIGHT = display.get_bounds()
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display.set_backlight(0) # turn off the white component of the backlight
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# the range of readings to map to colours (and scale our graph to)
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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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BRIGHTNESS = 0.5
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# the area of the screen we want to draw our graph into
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GRAPH_TOP = 24
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GRAPH_BOTTOM = 54
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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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display.set_pen(0)
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display.clear()
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display.set_pen(15)
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# From CPython Lib/colorsys.py
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def hsv_to_rgb(h, s, v): # noqa: RET503
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if s == 0.0:
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return v, v, v
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i = int(h * 6.0)
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f = (h * 6.0) - i
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p = v * (1.0 - s)
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q = v * (1.0 - s * f)
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t = v * (1.0 - s * (1.0 - f))
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i = i % 6
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if i == 0:
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return v, t, p
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if i == 1:
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return q, v, p
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if i == 2:
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return p, v, t
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if i == 3:
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return p, q, v
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if i == 4:
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return t, p, v
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if i == 5:
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return v, p, q
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highest = 0.0
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lowest = 4000.0
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readings = []
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# set up
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breakout_scd41.init(gp.i2c)
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breakout_scd41.start()
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gp.set_backlight(0, 0, 0, 127)
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display.set_font("bitmap8")
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display.set_pen(15)
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display.text("Waiting for sensor to be ready", 0, 0, WIDTH, 2)
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display.update()
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while True:
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if gp.switch_pressed(SWITCH_A):
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# reset recorded high / low values
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highest = 0.0
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lowest = 4000.0
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if breakout_scd41.ready():
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# read the sensor
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co2, temperature, humidity = breakout_scd41.measure()
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# update highest / lowest values
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if co2 < lowest:
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lowest = co2
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if co2 > highest:
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highest = co2
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# calculates a colour from the sensor reading
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hue = max(0, HUE_START + ((co2 - MIN) * (HUE_END - HUE_START) / (MAX - MIN)))
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# set the leds
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r, g, b = [int(255 * c) for c in hsv_to_rgb(hue / 360, 1.0, BRIGHTNESS)]
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gp.set_backlight(r, g, b, 0)
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# keep track of readings in a list (so we can draw the graph)
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readings.append(co2)
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# we only need to save a screen's worth of readings, so delete the oldest
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if len(readings) > WIDTH:
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readings.pop(0)
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# draw the graph
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clear()
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for r in range(len(readings)):
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# this line scales the y axis of the graph into the available space
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y = round(GRAPH_BOTTOM + ((readings[r] - MIN) * (GRAPH_TOP - GRAPH_BOTTOM) / (MAX - MIN)))
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display.pixel(r, y)
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# draw the text
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display.text("CO2", 0, 0, scale=2)
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display.text(f"Temp {temperature:.0f}°c", 0, 16, scale=1)
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display.text(f"Low {lowest:.0f}ppm", 0, HEIGHT - 8, scale=1)
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# measure the rest of the text before drawing so that we can right align it
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text_width = display.measure_text(f"{co2:.0f}ppm", scale=2)
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display.text(f"{co2:.0f}ppm", WIDTH - text_width, 0, scale=2)
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text_width = display.measure_text(f"Humidity {humidity:.0f}%", scale=1)
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display.text(f"Humidity {humidity:.0f}%", WIDTH - text_width, 16, scale=1)
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text_width = display.measure_text(f"High {highest:.0f}ppm", scale=1)
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display.text(f"High {highest:.0f}ppm", WIDTH - text_width, HEIGHT - 8, scale=1)
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display.update()
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