3 ms·
There might be yet another issue. As commented by the author of this blog post in the RPi forums (https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=243875
by cesarb 7y ago
There might be yet another issue. As commented by the author of this blog post in the RPi forums (https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=243875#p1492674 https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=2438...): "Also the 5v on the connector is connected directly to the 5v rails. If the pi is powered over the GPIO then the USB-C connector is vbus hot which means it could backfeed devices when using the type C port on the pi as a USB client."
That is, when powering the RPi4 through PoE, its USB-C connector is in an invalid configuration: it's powering VBUS when it shouldn't (that is, unlike USB-A where VBUS is always on, IIRC with USB-C it should only be turned on when the CC pins detect that the other side is either a power sink or an adapter which should source power).
- londons_explore 7y agoBackfeeding power is one of those things that is 'technically' a bad idea, but practically damages pretty much nothing.
- TylerWard 7y agoAnother potential issue here is that if using the Pi as a client with a C-C cable this could confuse the device at the other end meaning it wont connect as it thinks it is being charged (will be seeing if I can get this to occur over the weekend).
- TylerWard 7y agoHave just run this test and it does appear to confuse some USB-C ports (my phone and 3.0 usb-C port on my laptop detect the pi gadget however the 3.1 usb-C port doesn't detect the gadget if the pi is powered by gpio).