UBISS2024exam

 1 from machine import Pin, ADC
 2 from time import sleep
 3 
 4 # Initialize the light sensor (LDR) and LED
 5 ldr = ADC(Pin(12))
 6 led = Pin(20, Pin.OUT)
 7 
 8 def get_duty_cycle(light_value):
 9     # Map the light value to the duty cycle
10     # Completely dark (350) -> 90% on, 10% off
11     # Completely bright (790) -> 10% on, 90% off
12     min_light = 350
13     max_light = 790
14     min_duty = 90
15     max_duty = 10
16     
17     duty_cycle = min_duty + (max_duty - min_duty) * ((light_value - min_light) / (max_light - min_light))
18     return duty_cycle
19 
20 while True:
21     # Read the light value
22     light_value = ldr.read_u16()  # Read the analog value (16-bit)
23     light_value = (light_value / 65535) * (790 - 350) + 350  # Scale to 350-790 range
24 
25     # Calculate the duty cycle
26     duty_cycle = get_duty_cycle(light_value)
27     
28     # Calculate on and off times
29     on_time = duty_cycle / 100.0
30     off_time = 1.0 - on_time
31     
32     # Control the LED
33     led.on()
34     sleep(on_time)
35     led.off()
36     sleep(off_time)