ESP32-C6-DevKitC-1: 3.3V Pin Power Supply – NeoPixel/RGB LED Not Working

[tim_1337]

Hi everyone ,
I’m working with an ESP32-C6-DevKitC-1 and have a question about power supply options. According to the documentation, there are three (or four) ways to power the board:

• Via the USB-C port (5V)
• Via the USB-UART port (5V)
• Via the 5V pin + GND
• Via the 3.3V pin + GND

Issue:
When I power the board through the 3.3V pin + GND, the power LED lights up, but the built-in RGB LED (NeoPixel, GPIO8) cannot be controlled. However, if I supply 5V (or even 3.3V) to the 5V pin + GND, or use the USB ports, the LED works as expected.
Questions:

1. Are there known differences between powering via the 3.3V pin vs. 5V pin/USB?
   • Is the 3.3V pin handled differently internally (e.g., missing voltage regulation for certain components)?
   • Could the NeoPixel/GPIO8 be underpowered or not initialized correctly when using the 3.3V pin?
2. What is recommended for long-term or embedded use?
   • Is powering via the 5V pin (even with 3.3V!) more reliable?
   • Are there risks to supplying 3.3V to the 5V pin (e.g., for the voltage regulator)?
3. Has anyone else encountered this or have an explanation?

Background:
I plan to embed the board in a small project and am looking for the most reliable alternative to USB power, as USB ports are impractical for my final setup.

Technical Details:

• Board: ESP32-C6-DevKitC-1
• NeoPixel/RGB LED: Controlled via GPIO8 (using standard firmware/example code)
• Power source: Regulated PSU (3.3V/5V), sufficient current (>500mA)

Thanks in advance for your insights and experiences!

[Minatel]

Hi,

The RGB LED is connected to the 5V rails. Please see the schematic for version 1.4.
If you power on the 3V3, the LED will not work, as expected.

[tim_1337]

Thanks for the hint, the schematic makes that clear.