USB OTG port Power Off

#1

Hi,
I use ROCK Pi 4B v1.3, with Debian9Desktop from Radxa download. Kernel 4.4.154-90.
I want to use it as external USB storage for my PC.

I observed that OTG port after connection to host PC is consuming some power from the PC.
The value of current depends on voltage difference between PC USB voltage and ROCK Pi USB voltage.
This current is completely unwanted as it is only charges the voltage regulator on the ROCK Pi board.

Is there the software/hardware way to switch off the 5V power on the USB OTG port ?

#2

I don’t think you can turn off 5v line in usb without disabling datalink, but you may try this

But for sure you can just isolate 5v line like described there

#3

Thank you @Dante4 for the reply.
The USB cable with isolated VCC pin is what I’m using currently. This is what you suggested. The solution is working correctly but I’m looking for the solution from ROCK Pi 4 board side.

I thought rather of disconnecting power supply on ROCK Pi 4 side, by software.
I did some research and found on the schematic that power supply line VBUS_TYPEC which is put on USB3.0_OTG port can be controlled and toggled On/Off by signal VCC5V0_TYPEC0_EN.
The VCC5V0_TYPEC0_EN signal is taken from RK3399 chip port GPIO1_A3/ISP0_FLASHTRIGOUT/ISP1_FLASHTRIGOUT_d.
So curently I wonder if this port GPIO1_A3 can be controlled freely from bash (for example). Or maybe there are some limitation I should consider ?