Re:Raspberry Pi 4 as a USB-C peripheral
by kees99 on Saturday November 02, 2019 @06:48PM
(#21430659)
Am I reading this right that RPi4 has five usable USB ports, i.e. unlike earlier models, port on bottom left of the board can carry data along with power? This is awesome!
[ Parent
| on HN ]
USB-C includes a USB-2 management channel in addition to the high-bandwidth lanes. It is used for things like advanced power delivery negotiation. On the Raspberry Pi 4, the USB-C port has no high-bandwidth lanes, and it only uses passive power negotiation.
Re:Raspberry Pi 4 as a USB-C peripheral
by cesarb on Saturday November 02, 2019 @10:14PM
(#21431599)
> USB-C includes a USB-2 management channel in addition to the high-bandwidth lanes. It is used for things like advanced power delivery negotiation.
No, all the power delivery negotiation in USB-C, both the basic one using only passive resistor values and the advanced one using the USB-PD protocol, is through the configuration channel pins, which is a separate pair of pins completely independent from the USB 2.0 pins in the middle. (The configuration channel is implemented incorrectly on the Raspberry Pi 4, however; it shorts together the pins, while they should be separate, so it fails with advanced cables which use both pins; and when powered through a source other than the USB-C connector, it incorrectly sources 5V to the USB-C port even when it shouldn't.)
Re:Raspberry Pi 4 as a USB-C peripheral
by mmastrac on Saturday November 02, 2019 @08:55PM
(#21431273)
This seems to be in opposition to the blog post. In addition, according to the schematic there's USB-2 over that USB-C port:
https://www.raspberrypi.org/documentation/hardware/raspberry...