NY  wrote:
> "Deloptes"  wrote in message
> news:rcg7k0$heu$1@dont-email.me...
> > Chris Elvidge wrote:
> >
> >> Considering that
> >> the Pi 4's USB-C port is only usable for charging, chances are that you
> >> wouldn't want to use a high-speed data cable with it anyway.
> >
> > What a difference it makes? IMO none as the data part of the cable is not
> > being used

The USB 2 part of the USB-C socket is used by the Pi - that's where the Pi's
USB 2 controller is connected (the same component as provides previous Pis'
USB).  To use it, you need either a powered hub that's able to back-power
the Pi via the USB-C socket, or power the Pi via GPIO.

> But the Pi and the charger would probably still talk on the data lines when
> the cable was first inserted, to negotiate the charging voltage and current
> that was available from the charger and required by the Pi. The negotiation
> may be slightly different since the PSU is actually supplying the current
> that the Pi needs to operate, as opposed to charging a battery, so supplied
> reduced current (with a longer charging time) would not be an option - it's
> all or nothing.

This USB Power Delivery negotiation is on the CC1/CC2 lines on the USB C
connector, not on the USB signals.

Theo

--- SoupGate-Win32 v1.05