So I have an adsptrt that goes from battel to USB-C
That’s joy part of USB spec as there’s no way to communcate requirements through the barrel. Hard to blame USB for when we side-step it’s design.
I do stuff like this too, but only for devices that just need power, nothing like a laptop or with circuitry that could get fried by the wrong voltage.
daveyOsborn@infosec.pub 3 days ago
Do you mean the USB PD spec? It does not violate the USB spec which sets a default voltage of 5v. The adapter /would/ violate the USB PD spec if it were to claim to be USB PD compliant. But the shit-show we have is that USB-C does not imply USB PD. And so the market is full of USB-C things that are not USB PD. And often they do not claim to be USB PD as consumers are not wise enough to demand it.
Note as well the adapter I mentioned is quite dumb – just hardwires pins for the situation that the appliance expects 5v without negotiation. But it would be possible to implement a USB PD-compliant adaptor with the smarts to handshake, which would then refuse to complete the handshake in the event that the voltage supplied is not that requested. Of course it would be a bit strange to put that much sophistication into it which would likely drive the cost to that of a whole compliant PSU anyway (thus defeating the purpose). But notice the opposite has been done, whereby the adapter negotiates a voltage on behalf of a barrel device.
IIRC, it’s disputed whether the hanshake negotiation is needed for 5v. Some appliances expect to do a handshake /no matter what/, and some 5v appliances are designed to skip the negotiation entirely. If you are in the camp that says even 5v must have a handshake negotiation, then you would condemn the simple barrel to usb-c adapter (but perhaps not one that is only for a fixed input and the circuitry to do the negotiation).
The blame was not pin-pointed. I pointed out a shit show in the marketplace. There are bits of the standard you can blame, and you can also blame market actors. You can probably also blame regulators for not preventing the shit show that I described.