pimoroni-pico/micropython/examples/galactic_unicorn/light_sensor.py

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4.3 KiB
Python

import time
from galactic import GalacticUnicorn
from picographics import PicoGraphics, DISPLAY_GALACTIC_UNICORN as DISPLAY
"""
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
# Rate of display change i.e the lower the value the slower the transition
TRANSITION_RATE = 1.0 / 32.0
# 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 = gu.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" # set auto brightness on
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)
gu.set_brightness(brightness_value)
bp = (brightness_value / MAX_RANGE) * 100 # gets brightness value in percentage relative to the MAX_LS_VALUE set
# 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 to 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_percentage((WIDTH - 8), 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)