Polarity of barrel plug.

[stolk]

If I connect the lichee with my PC over USB-C, the device does not show up on my host's lsusb

Does the device require power from the barrel plug when connecting to the PC?

If so, is the centre pin GND or is the centre pin +12V? The wiki does not state the polarity of the barrel plug.

[stolk]

UPDATE: I see the device lsusb now, if I press and hold BOOT button on device.

But I still would like to know the polarity of the barrel plug, and whether it is req'd for operation, or if the device can be powered from USB-C alone.

[abelletti]

The center pin of the barrel is +12v. I agree, it would be helpful to mark this on the PCB or include in documentation. Instead I reviewed the schematic to be safe.

I'm powering mine from the +12v barrel plug, but have confirmed that it operates fine with only the USB-C powering it.

[Zepan]

Hi, it is mark on the PCB "VIN: 12V".
I checked it is work fine when powered from 12V.

[abelletti]

Hi Zepan, just to clarify, the problem isn't knowing what voltage. I agree, my board is clearly marked also. The problem is not knowing the polarity. While it is common for the center pin to be positive, it's not true 100% of the time. Marking that would save people needing to trace the schematic or gamble with their boards. Thanks!

[simcop2387]

A typical way to do this is with a symbol like this,

From the ISO-7000 / IEC-60417 standards, https://www.iso.org/obp/ui/#iso:pub:PUB400008:en