import time from stellar import StellarUnicorn from picographics import PicoGraphics, DISPLAY_STELLAR_UNICORN as DISPLAY """ Light sensoring feature for the stellar unicorn Uses the onboard light sensor to detect the light in the environment The brightness level is displayed as percentage. Brightness of the display is auto adjusted to the brightness level of the environment Press A to turn auto brightness on Press B to turn auto brightness off """ # set up unicorn and drawing variables su = StellarUnicorn() 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 # Rate of display change i.e the lower the value the slower the transition TRANSITION_RATE = 1.0 / 72.0 # 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 value it outside the ranges specified def calculate_brightness(prev_brightness_val): current_lsv = su.light() current_brightness_val = map_range(current_lsv) # uses the previous value to smooth out display changes reducing flickering brightness_diff = current_brightness_val - prev_brightness_val brightness_val = prev_brightness_val + (brightness_diff * TRANSITION_RATE) if brightness_val > 1: brightness_val = 1 elif brightness_val < 0.1: brightness_val = 0.1 return brightness_val # draws percentage icon def draw_percentage(x, y): graphics.rectangle(x + 1, y + 1, 2, 2) graphics.line(x + 1, y + 5, x + 6, y) graphics.rectangle(x + 4, y + 4, 2, 2) # 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() brightness_value = MIN_RANGE # set the initial brightness level to the specified minimum while True: current = time.ticks_ms() # set the display brightness brightness_value = calculate_brightness(brightness_value) su.set_brightness(brightness_value) bp = (brightness_value / MAX_RANGE) * 100 # gets brightness value in percentage relative to the MAX_LS_VALUE set # calculate brightness percentage bp = (brightness_value / MAX_RANGE) * 100 # deactivate auto brightness by pressing A if su.is_pressed(StellarUnicorn.SWITCH_A): print("Auto brightness off") mode = "off" # reactivate auto brightness by pressing A if su.is_pressed(StellarUnicorn.SWITCH_B): print("Auto brightness on") mode = "auto" # set brightness to default value if off if mode == "off": su.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(f"{bp:.0f}", 0, 1, scale=1) # measure the rest of the text before drawing to right align it text_width = graphics.measure_text(f"{bp:.0f}/°", scale=1) draw_percentage(10, 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 # update the display su.update(graphics)