I want to do what this 120W overunity USB device claims to do.



Except I am not stupid and I know that you can't get 20V/6A out of a laptop's 5V/500mA USB port, so I am looking for something that actually exists and doesn't break the laws of physics. Something that I can plug into external power, and into the laptop (USB A), and coming out of the device will be a USB-C cable that I can use to simultaneously charge and communicate with my camera.

There are many things like this for sale online, with various degrees of ridiculous lies and/or caveats.



But what they all have in common is that their power output is just converted from the 5V USB-A port, so they can't possibly offer rapid charging. I need basically a USB-C "injector."

Does this thing I want exist? If so, please tell me what name it goes by, so that I may find it.

 

Probably not.
If You find one, it's likely to be quite expensive.
It might be time to upgrade your LapTop.
.
.
.

 

Probably not.
If You find one, it's likely to be quite expensive.
It might be time to upgrade your LapTop.
.
.
.

Well I'm only using the laptop for development. The laptop will ultimately be replaced by a Raspberry Pi. I don't know if any future Pi is scheduled to come out with a USB-C output port.

I can't believe this isn't a thing. I can't be the only one needing this. There must be some kind "gotcha" why this can't exist? What is it?

Could I roll my own with a USB-C pass-through breakout board like this??





Everything would be connected straight through from the rapid charger to the camera, except for the data pins which would come from the laptop's USB-A port. What is the fly in the ointment that would prevent it from working?

 

Well I'm going to try it. I'll stack 3 of these breakout boards.

• Center board goes to the camera.
• Top board comes from PD3.0 charger. All pins connected to center board except D+ and D-
• Bottom board comes from laptop/RPi. No pins are connected to center board except Gnd, Shield, D+ and D-

 

I have several USB hubs that use an external power source, hence supply more than they draw. Is that what you are after?

 

Your problem will be that Type-C uses the D+ and D- to work out the proper power to provide. If the data lines are connected to the USB-A connector they won’t be able to be used by the Type-C power.

However, if you use a Type-C trigger board you could select a fixed power by connecting it to the D+ and D- of the Type-C supply, and use it to replace negotiation.

 

I have several USB hubs that use an external power source, hence supply more than they draw. Is that what you are after?

Well, yes, but with a coupe of very important details.

1. The camera requires USB-C PD3.0 ("super fast" rapid charger) or better.
2. The only available USB interface to the computer is USB-A

I have seen USB hubs that use external power sources. They are almost exclusively with USB-A only outputs.
I have seen USB hubs that have USB-A input and USB-C outputs, even ones with external power, but the USB-C outputs are not PDx.x
I have seen USB hubs that have USB-C PDx.x charging capability. They are almost exclusively with USB-C input.

I have seen zero USB hubs that meet my requirements. But if you have one that would work, please let me know so I can look it up.

 

Your problem will be that Type-C uses the D+ and D- to work out the proper power to provide. If the data lines are connected to the USB-A connector they won’t be able to be used by the Type-C power.

Are you positive about that? What I have read so far indicates that there is a separate comms bus for that (Pins A5, B5), and D+/D- is just for USB2.0 communication



The diagram below for a USB-A to USB-C cable mentions the pullup resistors that I think are used to tell a device that the source is USB-A and has no rapid charge ability, but these are connected to Vbus, not D+/D-.




Am I missing something? I really have no idea what I'm talking about so don't hesitate to set me straight.

However, if you use a Type-C trigger board you could select a fixed power by connecting it to the D+ and D- of the Type-C supply, and use it to replace negotiation.

Can you expound? I'm not sure I understand. I don't actually know what voltage the camera negotiates from a PD power supply and I would be afraid to feed it something it didn't want. And I think that lack of PD comms is what makes it not work anyway. I can connect a regular USB-A to USB-C cable to the camera and communicate with it; it just won't charge (I think, because it knows the supply isn't PD)

 

Are you positive about that? What I have read so far indicates that there is a separate comms bus for that (Pins A5, B5), and D+/D- is just for USB2.0 communication

View attachment 293402

The diagram below for a USB-A to USB-C cable mentions the pullup resistors that I think are used to tell a device that the source is USB-A and has no rapid charge ability, but these are connected to Vbus, not D+/D-.


View attachment 293400

Am I missing something? I really have no idea what I'm talking about so don't hesitate to set me straight.


Can you expound? I'm not sure I understand. I don't actually know what voltage the camera negotiates from a PD power supply and I would be afraid to feed it something it didn't want. And I think that lack of PD comms is what makes it not work anyway. I can connect a regular USB-A to USB-C cable to the camera and communicate with it; it just won't charge (I think, because it knows the supply isn't PD)

You are correct, CC2 is the PD communications pin, but I had the idea that before that can be used other negotiation sequences occurred over D+/D-. Unfortunately, the PD specification is very complicated and I am having a great deal of trouble finding the definitive answer in the spec.

I read it through in the past because PD is so mysterious, but it’s even too large to post here, so here’s a link to it. You can see if it is helpful, but the truth is the documentation is so siloed I am not even sure th answer is in this document.

 

You are correct, CC2 is the PD communications pin, but I had the idea that before that can be used other negotiation sequences occurred over D+/D-. Unfortunately, the PD specification is very complicated and I am having a great deal of trouble finding the definitive answer in the spec.

I read it through in the past because PD is so mysterious, but it’s even too large to post here, so here’s a link to it. You can see if it is helpful, but the truth is the documentation is so siloed I am not even sure th answer is in this document.

Wow, only 868 pages? Thanks for the link. I've already ordered the breakout boards and I think I am going to learn this the way I learn most other things: First, do it. If/When it doesn't work, then open the book to find out why. When I break this tradition it often results in over-analysis and dwindling confidence, followed by either a knee-jerk "just do it" impulse or a loss of interest. Sometimes (when safety is a consideration) I am forced to do things in the traditional "proper" order but I am not overly concerned about it in this case.

 

Wow, only 868 pages? Thanks for the link. I've already ordered the breakout boards and I think I am going to learn this the way I learn most other things: First, do it. If/When it doesn't work, then open the book to find out why. When I break this tradition it often results in over-analysis and dwindling confidence, followed by either a knee-jerk "just do it" impulse or a loss of interest. Sometimes (when safety is a consideration) I am forced to do things in the traditional "proper" order but I am not overly concerned about it in this case.

The PD trigger boards might work in your case unless the camera demands negotiation, keep I’m mind, though, the output of the trigger will never be vSafe5V that is supposed to be the starting point every time so be cautious what you plug it into.