CAF LED blinks on wake up event

RE: CAF LED blinks on wake up event

bicanoff — Thu, 26 Sep 2024 07:47:36 GMT

I had a similar problem with blinking after every wake-up from sleep. In my case, I set CONFIG_CAF_LEDS_PM_EVENTS=n to solve this problem. (NCS 2.6.1)

RE: CAF LED blinks on wake up event

Elfving — Thu, 23 Nov 2023 15:05:24 GMT

I see. I figured this could be issue NCSDK-15707, though that should be fixed in your NCS version.

Workaround: Make sure your application includes the devicetree overlay file in which PWM period is decreased. For example, include the following commit to solve the issue for the nRF Machine Learning application for Nordic Thingy:53: fa2b57cddbaacf393c77def5d0302e1a45138d21

Could you try if this workaround still helps at all? And when it likely won't, could you provide some minimally reproducing this issue?

Regards,

Elfving

RE: CAF LED blinks on wake up event

zhangxka — Tue, 21 Nov 2023 22:52:52 GMT

This is the LED I'm using. I'm using NCS 2.3.0.
https://datasheet.lcsc.com/lcsc/2001151003_MEIHUA-MHSC110RGBCT_C482558.pdf

CAF LED module works fine otherwise (adjusting color/brightness)

RE: CAF LED blinks on wake up event

Elfving — Tue, 21 Nov 2023 11:50:47 GMT

I see. What sort of led is this? What is your NCS version?

Regards,

Elfving

RE: CAF LED blinks on wake up event

zhangxka — Tue, 21 Nov 2023 07:17:25 GMT

Hi Elfving,

Thanks for the reply. I actually tried that with the following code but still got the LED to blink when system wakes up.

In my app_event_handler, I have

    if (is_power_down_event(aeh)) {
        return handle_power_down_event(cast_power_down_event(aeh));
    }

static bool handle_power_down_event(const struct power_down_event *event) {
  LOG_DBG("Handling power down event");
  led_turn_off(LED_USER);
  return false;
}

led_turn_off would submit a new_led_event to turn the LED off.

This problem seems to be related to something that is triggered when PWM starts back up. The blink is very brief (maybe about 20ms?), but is still is visible. Even if LED doesn't turn on in any part of my code, the power manager + PWM LED module themselves are able to trigger the symptom here.

RE: CAF LED blinks on wake up event

Elfving — Mon, 20 Nov 2023 14:55:23 GMT

Hello Kevin,

If you assign a new LED effect on wake_up_event processing, the old effect would still be in use for time between wake_up_event processing and processing of the led_event turning off LEDs that is submitted by you.

We would suggest assigning the new LED effect earlier (e.g. on power_down_event) to ensure that the LED effect is set before wake_up_event is processed.

Regards,

Elfving