from machine import Pin, PWM, Timer, I2C, UART
import time

def led_blink(t):
    for duty_cycle in range(55536, 65536, duty_step):
        led_blue.duty_u16(duty_cycle)
        led_green.duty_u16(duty_cycle)
        led_red.duty_u16(duty_cycle)
        time.sleep(0.05)

    for duty_cycle in range(65535, 55535, -duty_step):
        led_blue.duty_u16(duty_cycle - 1)
        led_green.duty_u16(duty_cycle - 1)
        led_red.duty_u16(duty_cycle - 1)
        time.sleep(0.05)


frequency = 10000
duty_step = 100

led_blue = PWM(Pin(25))
led_blue.freq(frequency)
led_green = PWM(Pin(16))
led_green.freq(frequency)
led_red = PWM(Pin(17))
led_red.freq(frequency)

tim = Timer(-1)
tim.init(period=10000, mode=Timer.PERIODIC, callback=led_blink)