Added light sensor example with auto brightness feature

micropython/examples/galactic_unicorn/light_sensor.py

@@ -0,0 +1,120 @@
+import time
+from galactic import GalacticUnicorn
+from picographics import PicoGraphics, DISPLAY_GALACTIC_UNICORN as DISPLAY
+import math
+
+'''
+Auto brightness feature for the galactic unicorn
+Uses the onboard light sensor to detect the light
+The brightness percentage is displayed with brightness auto adjusted
+'''
+# set up unicorn and drawing variables
+gu = GalacticUnicorn()
+graphics = PicoGraphics(DISPLAY)
+
+WIDTH, HEIGHT = graphics.get_bounds()
+BLACK = graphics.create_pen(0, 0, 0)
+WHITE = graphics.create_pen(255, 255, 255)
+GREY = graphics.create_pen(20, 20, 20)
+HUE_START = 0
+HUE_END = 100
+graphics.set_font("bitmap8")
+
+# Text display sleep time in ms
+TEXT_SLEEP = 500
+
+
+# the onboard light sensor has a wide range from 0 t0 4095
+# It is therefore needed to set a lower max and a higher minimum
+MIN_LS_VALUE = 10
+MAX_LS_VALUE = 295 # 4095 to use the full range
+MIN_RANGE = 0.1
+MAX_RANGE = 1
+
+
+# perform linear interpolation to map a range of values to discrete
+def map_range(x, min_input = MIN_LS_VALUE,
+                  max_input = MAX_LS_VALUE,
+                  min_output = MIN_RANGE,
+                  max_output = MAX_RANGE):
+    return (x - min_input) * (max_output - min_output) / (max_input - min_input) + min_output
+    
+
+# gets the light sensor value from onboard sensor and interpolates it
+# clamps the brightness values
+def calculate_brightness(current_lsv):
+    brightness_value = map_range(current_lsv)
+    if brightness_value > 1:
+        brightness_value = 1
+    elif brightness_value < 0.1:
+        brightness_value = 0.1
+        
+    return brightness_value
+
+
+# sets up a handy function we can call to clear the screen
+def clear():
+    graphics.set_pen(BLACK)
+    graphics.clear()    
+
+mode = "auto"
+last = time.ticks_ms()
+while True:
+    current = time.ticks_ms()
+    
+    
+    
+    # get light sensor value from the sensor
+    ls_value = gu.light()
+    brightness_value = calculate_brightness(ls_value)
+    gu.set_brightness(brightness_value)
+    # calculate brightness percentage
+    bp = (brightness_value / MAX_RANGE) * 100
+    
+    # deactivate auto brightness by pressing A
+    if gu.is_pressed(GalacticUnicorn.SWITCH_A):
+        print("Auto brightness off")
+        mode = "off"
+        
+    # reactivate auto brightness by pressing A
+    if gu.is_pressed(GalacticUnicorn.SWITCH_B):
+        print("Auto brightness on")
+        mode = "auto"
+        
+    # set brightness to default value if off
+    if mode == "off":
+        gu.set_brightness(0.5)
+    
+    # set text update rate after a certain time to reduce flickering 
+    if current - last >= TEXT_SLEEP:
+        clear()
+        
+        # calculate colour from the brightness value
+        hue = max(0, HUE_START + ((bp - 0) * (HUE_END - HUE_START) / (100 - 0)))
+        
+        # create pens with this colour (and with the high / low colours)
+        CURRENT_COLOUR = graphics.create_pen_hsv(hue / 360, 1.0, 0.8)
+        HIGH_COLOUR = graphics.create_pen_hsv(HUE_END / 360, 1.0, 0.8)
+        LOW_COLOUR = graphics.create_pen_hsv(HUE_START / 360, 1.0, 0.8)
+
+        # draw the text
+        graphics.set_pen(CURRENT_COLOUR)
+        graphics.text("BRT: ", 0, 1, scale=1)
+        # measure the rest of the text before drawing so that we can right align it
+        text_width = graphics.measure_text(f"{bp:.0f}/°", scale=1)
+        graphics.text(f"{bp:.0f}%", WIDTH - text_width, 1, scale=1)
+        
+        # draw a bar for the background
+        graphics.set_pen(GREY)
+        graphics.rectangle(0, 9, WIDTH, 10)
+
+        # draw a bar for the current brightness percentage
+        graphics.set_pen(CURRENT_COLOUR)
+        graphics.rectangle(0, 9, int((bp / 100) * WIDTH), 10)
+        last = current
+
+    # time to update the display
+    gu.update(graphics)
+    # time.sleep(1)
+
+