Why can't I measure voltage at 3.3v
Even a LED bulb cannot detect voltage, while at 5.0V, it lights
Using arduino UNO
Is your board UNO R4 Minima or UNO R3?
You can use your multimeter set in 20V DC voltmeter range to measure between 3.3V and GND pins when your board is connected to your computer via USB.
I do not know the difference, but that is the image...
I am using a smart multimeter in auto mode, and it 'beeps' when i connect GND and 3.3v (continuity)
it's being detected well by pc USB-SERIAL CH340 (COM10)
The board is not an official Arduino board, but a clone.
It's also not an R4. It's an R3.
Maybe the company that knocked it off didn't build it right. Some of those clones are very poor quality.