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by fanf2
2426 days ago
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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. |
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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.)