add sensor examples

micropython/examples/plasma_stick/co2.py

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+import plasma
+from plasma import plasma2040
+import breakout_scd41 as scd
+from pimoroni_i2c import PimoroniI2C
+
+"""
+Reads CO2 level from an SCD41 breakout...
+... and changes the LED strip an appropriate colour.
+https://shop.pimoroni.com/products/scd41-co2-sensor-breakout
+"""
+
+# set how many LEDs you have
+NUM_LEDS = 50
+
+BRIGHTNESS = 1.0
+
+# the range of readings to map to colours
+# https://www.kane.co.uk/knowledge-centre/what-are-safe-levels-of-co-and-co2-in-rooms
+MIN = 400
+MAX = 2000
+
+# pick what bits of the colour wheel to use (from 0-360°)
+# https://www.cssscript.com/demo/hsv-hsl-color-wheel-picker-reinvented/
+HUE_START = 100  # green
+HUE_END = 0  # red
+
+# WS2812 / NeoPixel™ LEDs
+led_strip = plasma.WS2812(NUM_LEDS, 0, 0, plasma2040.DAT)
+
+# Start updating the LED strip
+led_strip.start()
+
+# set up I2C
+PINS_BREAKOUT_GARDEN = {"sda": 4, "scl": 5}
+i2c = PimoroniI2C(**PINS_BREAKOUT_GARDEN)
+
+# set up SCD41 breakout
+scd.init(i2c)
+scd.start()
+
+print("Waiting for SCD41 to be ready")
+
+while True:
+    if scd.ready():
+        co2, temperature, humidity = scd.measure()
+        print(f"""
+CO2:         {co2} ppm
+Temperature: {temperature:.2f} °C
+Humidity:    {humidity:.2f} %""")
+
+        # calculates a colour
+        hue = HUE_START + ((co2 - MIN) * (HUE_END - HUE_START) / (MAX - MIN))
+
+        # set the leds
+        for i in range(NUM_LEDS):
+            led_strip.set_hsv(i, hue / 360, 1.0, BRIGHTNESS)

micropython/examples/plasma_stick/thermometer_bme280.py

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+import plasma
+from plasma import plasma2040
+import time
+from breakout_bme280 import BreakoutBME280
+from pimoroni_i2c import PimoroniI2C
+
+"""
+Reads the temperature from a BME280 breakout...
+...and changes the LED strip an appropriate colour.
+https://shop.pimoroni.com/products/bme280-breakout
+"""
+
+# Set how many LEDs you have
+NUM_LEDS = 50
+
+BRIGHTNESS = 1.0
+
+# The range of readings that we want to map to colours
+MIN = 10
+MAX = 30
+
+# pick what bits of the colour wheel to use (from 0-360°)
+# https://www.cssscript.com/demo/hsv-hsl-color-wheel-picker-reinvented/
+HUE_START = 230  # blue
+HUE_END = 359  # red
+
+# WS2812 / NeoPixel™ LEDs
+led_strip = plasma.WS2812(NUM_LEDS, 0, 0, plasma2040.DAT)
+
+# Start updating the LED strip
+led_strip.start()
+
+# set up I2C
+PINS_BREAKOUT_GARDEN = {"sda": 4, "scl": 5}
+i2c = PimoroniI2C(**PINS_BREAKOUT_GARDEN)
+
+# set up BME280 breakout
+bme = BreakoutBME280(i2c)
+
+while True:
+    temperature, pressure, humidity = bme.read()
+    print(f"""
+Temperature: {temperature:.2f} °C
+Humidity: {humidity:.2f} %
+Pressure: {pressure / 100:.2f} hPa
+     """)
+
+    # calculates a colour
+    hue = HUE_START + ((temperature - MIN) * (HUE_END - HUE_START) / (MAX - MIN))
+
+    # set the leds
+    for i in range(NUM_LEDS):
+        led_strip.set_hsv(i, hue / 360, 1.0, BRIGHTNESS)
+
+    time.sleep(0.5)

micropython/examples/plasma_stick/thermometer_pico.py

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+import plasma
+from plasma import plasma2040
+import machine
+import time
+
+"""
+Reads the internal temperature sensor on the Pico W...
+... and changes the LED strip an appropriate colour.
+"""
+
+# Set how many LEDs you have
+NUM_LEDS = 50
+
+BRIGHTNESS = 1.0
+
+# The range of readings that we want to map to colours
+MIN = 10
+MAX = 30
+
+# pick what bits of the colour wheel to use (from 0-360°)
+# https://www.cssscript.com/demo/hsv-hsl-color-wheel-picker-reinvented/
+HUE_START = 230  # blue
+HUE_END = 359  # red
+
+# WS2812 / NeoPixel™ LEDs
+led_strip = plasma.WS2812(NUM_LEDS, 0, 0, plasma2040.DAT)
+
+# Start updating the LED strip
+led_strip.start()
+
+sensor_temp = machine.ADC(4)
+conversion_factor = 3.3 / (65535)  # used for calculating a temperature from the raw sensor reading
+
+# The Pico's temperature sensor is not super accurate and readings jump around
+# lets do some averaging to avoid annoying flashing
+n = 0
+temperature = 20  # a dummy value to fill the array
+temperature_array = [temperature] * 10  # average over 10 readings (5 secs)
+
+while True:
+    # read the sensor
+    # the following two lines do some maths to convert the number from the temp sensor into celsius
+    reading = sensor_temp.read_u16() * conversion_factor
+    temperature = 27 - (reading - 0.706) / 0.001721
+
+    # add the most recent reading to the array
+    if n >= len(temperature_array):
+        n = 0
+    temperature_array[n] = temperature
+    n += 1
+
+    temperature_average = sum(temperature_array)/len(temperature_array)
+    print(f"""
+    Average temperature: {temperature_average:.2f} °C
+    """)
+
+    # calculates a colour
+    hue = HUE_START + ((temperature_average - MIN) * (HUE_END - HUE_START) / (MAX - MIN))
+
+    # set the leds
+    for i in range(NUM_LEDS):
+        led_strip.set_hsv(i, hue / 360, 1.0, BRIGHTNESS)
+
+    time.sleep(0.5)