Green Flash on Startup


Does anyone have any insight as to why my LED’s (WS2815’s) very briefly do a green flash once on startup?

It seems like they flash when they get 12V and maybe the ESP32 has not started sending data to the LED’s yet?

Does it occur if you power up the LEDs with no MCU attached to Data IN?

Some GPIO pins will briefly output serial or PWM data on power up.
You could try a different pin for data.


I have a ESP32 dev board hooked up to a SN74AHCT125.

When I turn on the +12v with the DATA lines unplugged I see some of the LED’s do a very brief green flash. (~5%).
On another setup I have they all do the brief green flash and it appears brighter/longer. Still prob less then 250 ms.

Could it have to do with the rise time of the 12v?

That is why a relay is supported. It keeps LED power off until the ESP boots.

Yah possibly one way to check would be to use a 12V Gel cell as your power source and no data.
Should have huge startup current capability.
Do you have any capacitors in parallel with the strip?

Thanks for the replies. I think The latest version of LED chip may fix this issue.
Backup plan will be to add a small relay.
Does the relay only come on after DATA is being sent out?

It comes on when the brightness is over zero.