Stellar: add temperature example

micropython/examples/stellar_unicorn/README.md

@@ -12,6 +12,7 @@
   - [Nostalgia Prompt](#nostalgia-prompt)
   - [Rainbow](#rainbow)
   - [Scrolling Text](#scrolling-text)
+  - [Thermometer](#thermometer)
   - [Today](#today)
 - [Wireless Examples](#wireless-examples)
   - [Cheerlights History](#cheerlights-history)
@@ -105,6 +106,12 @@ Some good old fashioned rainbows! You can adjust the cycling speed with A and B,
 
 Display scrolling wisdom, quotes or greetz. You can adjust the brightness with LUX + and -.
 
+
+### Thermometer
+[thermometer_pico.py](thermometer_pico.py)
+
+Shows the temperature (from the Pico W's internal sensor) against an appropriately coloured pulsing blob.
+
 ### Today
 
 [today.py](today.py)

micropython/examples/stellar_unicorn/thermometer_pico.py

@@ -0,0 +1,103 @@
+from machine import ADC
+import time
+from stellar import StellarUnicorn
+from picographics import PicoGraphics, DISPLAY_STELLAR_UNICORN
+
+"""
+Reads the internal temperature sensor on the Pico W...
+... and displays an appropriately coloured pulsing blob.
+"""
+
+# The range of readings that we want to map to colours
+MIN = 15
+MAX = 35
+
+# 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
+
+# rainbow party mode
+rainbow_orb = False
+
+# set up the Unicron
+su = StellarUnicorn()
+graphics = PicoGraphics(DISPLAY_STELLAR_UNICORN)
+
+# set up the ADC
+sensor_temp = ADC(ADC.CORE_TEMP)
+conversion_factor = 3.3 / 65535  # used for calculating a temperature from the raw sensor reading
+
+# set up constants and variables for drawing
+WIDTH, HEIGHT = graphics.get_bounds()
+
+BLACK = graphics.create_pen(0, 0, 0)
+WHITE = graphics.create_pen(255, 255, 255)
+
+forward = True
+orb_brightness = 0.5
+hue = 0.0
+
+graphics.set_font("bitmap8")
+
+while True:
+
+    # read the onboard 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
+
+    print(f"""
+    Temperature: {temperature:.2f} °C
+    """)
+
+    # fills the screen with black
+    graphics.set_pen(BLACK)
+    graphics.clear()
+
+    # draw a weird orb:
+    # three overlapping circles with varying saturations
+    if rainbow_orb is True:
+        graphics.set_pen(graphics.create_pen_hsv((hue / 360), 0.5, orb_brightness))
+        graphics.circle(8, 8, 7)
+        graphics.set_pen(graphics.create_pen_hsv((hue / 360), 0.7, orb_brightness))
+        graphics.circle(7, 7, 7)
+        graphics.set_pen(graphics.create_pen_hsv((hue / 360), 1.0, orb_brightness))
+        graphics.circle(7, 7, 5)
+        hue += 0.01 * 360
+    else:
+        # calculate a colour from the temperature
+        hue = max(0, HUE_START + ((temperature - MIN) * (HUE_END - HUE_START) / (MAX - MIN)))
+        graphics.set_pen(graphics.create_pen_hsv((hue / 360), 0.6, orb_brightness))
+        graphics.circle(8, 8, 7)
+        graphics.set_pen(graphics.create_pen_hsv((hue / 360), 0.8, orb_brightness))
+        graphics.circle(7, 7, 7)
+        graphics.set_pen(graphics.create_pen_hsv((hue / 360), 1.0, orb_brightness))
+        graphics.circle(7, 7, 5)
+
+    # pulse the orb!
+    if forward is True:
+        orb_brightness += 0.01
+    if orb_brightness >= 0.7:
+        orb_brightness = 0.7
+        forward = False
+
+    if forward is False:
+        orb_brightness -= 0.01
+    if orb_brightness <= 0.3:
+        orb_brightness = 0.3
+        forward = True
+
+    # draw the temperature
+    # try BLACK for a funky negative space effect
+    graphics.set_pen(WHITE)
+    graphics.text(f"{temperature:.0f}°", 2, 5, scale=1)
+
+    # or uncomment these lines if you'd prefer it in Freedom Units
+    # graphics.set_pen(WHITE)
+    # fahrenheit = (temperature_average * 9 / 5) + 32
+    # graphics.text(f"{fahrenheit:.0f}°", 2, 5, scale=1)
+
+    # time to update the display
+    su.update(graphics)
+    time.sleep(0.1)