USB-C Charging on the PBP?

[moonwalkers]

Power supply specs from the wiki  "USB-C 5V, 15W PD quickcharge" seems incorrect. If it's fixed at 5V then it's not "PD". 

K, the first time I actually played along with this, the second time I just kept quiet, but now I'm actually getting a bit annoyed...

Without PD USB can deliver up to six unit loads for high power SuperSpeed devices, where the unit load is 150mA on USB 3.0 (SuperSpeed) and 250mA for multi-lane SuperSpeed. That means without PD USB can deliver up to 7.5W. USB PD was developed specifically to standardize the way to deliver more than 7.5W of power, and than includes 15W, the maximum power deliverable without increasing voltage. So technically 15W delivery in PBP is USB PD, compliant with revision 2 or 3 of the standard, though saying "quickcharge" is indeed a bit of a misnomer since that would imply a different proprietary technology by Qualcomm that predates USB PD standard and AFAIK is available only on their Snapdragon platform.

That said, IMNSHO 15W is barely adequate for PBP.

Thanks for the reply, sorry to annoy. I must have misunderstood, this chart seems to suggest that usb-c is capable of 15w without the PD standard and 100w with it.


https://en.wikipedia.org/wiki/USB_hardware#Power

Edit: Video

No need to apologize - consulting the USB Type-C and USB Power Delivery specification documents directly from https://www.usb.org/documents looks like we may turn out to be both right and wrong at the same time, since both standards were introduced at the same time and are highly intertwined and somewhat confusing.

Based on USB Type-C doc, it looks like non-PD ports can indeed supply (and I assume draw too, that I haven't found explicit mention of that) up to 3A at 5V without actually implementing USB PD, though the mechanism for that negotiation is outside of typical USB protocol of using discreet unit loads. Non-USBPD ports can still be DRP (dual role port), in that case whether they draw or supply power is determined by the other device connected to them, whether it is sink-only or source-only.

Based on USB PD doc, what determines whether device is a PD device is whether it uses so-called SOP packets to negotiate power flow direction (which device is a sink and which is a source) and a combination of voltage and current after establishing initial USB link. PD-compliance cannot be judged on power alone if it's below 15W, because PD standard explicitly covers low-power uses like USB-C headphones, just like it cannot be judged on power flow direction alone.

So what can we do to verify whether PBP's type C port actually implements USB PD? Well, it looks like with PD (unlike non-PD type C) it should be possible to swap between DFP and UFP (downstream/upstream flow port) roles on a DRP like the one in PBP clearly is, so long as the other device connected to it is also a DRP. So I believe if one has, say, an Android phone with USB PD where they can select that phone should be charging the attached device then if PBP's type C port actually supports USB PD then it should be possible to do both, charge such phone from PBP as well as charge PBP from such phone. With one caveat - the type C cable used to connect the two devices also has to be PD-compliant *sigh*. At the moment I have neither such cable nor such phone handy so I cannot do the test, if someone else does and can verify it for all of us - that would be awesome.

Now, who was it claiming that USB is simpler than barrel plug? :-D

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Ah, much simpler than the test I proposed:

The Power Delivery Specification, in addition to providing mechanisms to negotiate power also can be used as a side-
band channel for standard and vendor defined messaging. Power Delivery enables alternative modes of operation by
providing the mechanisms to discover, enter and exit Alternate Modes. The specification also enables discovery of
cable capabilities such as supported speeds and current levels.

Since PBP supports DisplayPort alternate mode over the type C port that by necessity means it implements USB Power Delivery specification.