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modsocket.c

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  • soft_pwm.py NaN GiB
    import utime
    from hwconfig import LED
    
    
    # Using sleep_ms() gives pretty poor PWM resolution and
    # brightness control, but we use it in the attempt to
    # make this demo portable to even more boards (e.g. to
    # those which don't provide sleep_us(), or provide, but
    # it's not precise, like would be on non realtime OSes).
    # We otherwise use 20ms period, to make frequency not less
    # than 50Hz to avoid visible flickering (you may still see
    # if you're unlucky).
    def pwm_cycle(led, duty, cycles):
        duty_off = 20 - duty
        for i in range(cycles):
            if duty:
                led.value(1)
                utime.sleep_ms(duty)
            if duty_off:
                led.value(0)
                utime.sleep_ms(duty_off)
    
    
    # At the duty setting of 1, an LED is still pretty bright, then
    # at duty 0, it's off. This makes rather unsmooth transition, and
    # breaks fade effect. So, we avoid value of 0 and oscillate between
    # 1 and 20. Actually, highest values like 19 and 20 are also
    # barely distinguishible (like, both of them too bright and burn
    # your eye). So, improvement to the visible effect would be to use
    # more steps (at least 10x), and then higher frequency, and use
    # range which includes 1 but excludes values at the top.
    while True:
        # Fade in
        for i in range(1, 21):
            pwm_cycle(LED, i, 2)
        # Fade out
        for i in range(20, 0, -1):
            pwm_cycle(LED, i, 2)