Powered USB Hub Charge Problem

[quarky42]

My Diamond and TP both would charge from this four port POWERED USB HUB that I have. The hub puts out 1A of current (even though it is shared, it is able to put out an amp at an individual port).

My TP2 will only charge from this hub when the computer that the hub is attached to is powered on. This is very annoying. I have several gadgets that I charge off and on from this USB hub and I would like to avoid having tons of power supplies plugged in.

If I turn the computer on, the phone will charge. If the computer is off but the hub is still on all the time the TP2 won't charge.

Does anyone know of a way around this? Is there a registry hack/setting that would allow the phone to charge from a USB hub without the computer being on? I have tried a couple different 1% battery drivers. They don't seem to affect it. I've tried it without those drivers installed too. I have not tried the USB Fast Charge update yet, would like some feedback if anyone else has run into a similar problem.

I believe this problem is similar to charging your phone while your computer is in standby. My laptop puts out a lot of current at the USB ports, even in standby. I was able to fully charge my TP and Diamond phones from my laptop even when the system is in standby. I don't think I can charge the TP2 while the laptop is in standby.

[i360]

Bump...

I searched for this via the net and your thread popped up. I have the same issue.

I was able to charge my Mogul, Touch Pro 1 and even my girls Touch (Elf or whatever) and all charge with my computer off (my computer has powered USB ports) but the Touch Pro 2 asks what connection I want and won't charge.

Now since its asking what I wanna do I know it knows the USBs are powered, it just refuses to charge. So it must be a setting on the TP2 since the actual computer is off so thats eliminated from the equation.

Any help would be nice, thanks.

[TheBundo]

The issue is probably this, and I just learned it after midnight today, believe it or not. I was finally reading the pdf manual on my new Toshiba laptop, and discovered that this laptop could charge my phone while in Sleep mode, IF IT WAS HOOKED up to the USB port with the "lightning" symbol next to the USB symbol (I'm sure everyone else already knew that).

BUT it also said that if there was too much drain, and the threshold is LESS than it is when the computer is ON, then it will not work. It mentioned that some devices take too much power to work in the Sleep mode, but charge fine when the computer is on.

I tested my Toshiba, and the TP2 DID charge on that USB port when the computer was in Sleep. However, the combined drain from your TP2 AND the HUB may exceed the limit, and hence you get no charge.

Could that be the issue? Becuase the hub must create a little overhead amperage draw...........

[santod]

For this we need to look at USB’s electrical specs, especially the power sinking and supplying parts.
There are 3 classes of USB hosts and 3 classes of USB devices/functions defined in the specs. Hosts are devices like PCs, USB hubs, etc, which can connect to multiple devices and act as the “Master” in most transactions. Devices are “Slaves” in a USB connection. All cameras, phones, thumb drives, etc are considered as devices.

The power source and sink requirements of different device classes can be simplified with the introduction of the concept of a unit load. A unit load is defined to be 100 mA. A device may be either low-power at one unit load (100mA) or high-power, consuming up to five unit loads (500mA). All devices default to low-power. The transition to high-power is under software control. It is the responsibility of software to ensure adequate power is available before allowing devices to consume high-power.

So the 3 USB Host Classes are..

Root port hubs: These are directly attached to the USB Host Controller. Systems that obtain operating power externally, either AC or DC, must supply at least five unit loads to each port
Bus-powered hubs: Draw all of their power for any internal functions and downstream facing ports from VBUS on the hub’s upstream facing port. Bus-powered hubs may only draw up to one unit load upon power-up and five unit loads after configuration.
Self-powered hubs: Power for the internal functions and downstream facing ports does not come from VBUS. However, the USB interface of the hub may draw up to one unit load from VBUS on its upstream facing port to allow the interface to function when the remainder of the hub is powered down.

And the 3 USB Device Classes are..

Low-power bus-powered functions: All power to these devices comes from VBUS. They may draw no more than one unit load at any time.
High-power bus-powered functions: All power to these devices comes from VBUS. They must draw no more than one unit load upon power-up and may draw up to five unit loads after being configured.
Self-powered functions: May draw up to one unit load from VBUS to allow the USB interface to function when the remainder of the function is powered down. All other power comes from an external (to the USB) source.

So basically, there are hosts that can supply up to 500mA and devices which can sync up to 500mA. However, all hosts and devices will default to supplying and sinking (respectively) 100mA. And to switch to the high power mode, the device software (USB Stack) has to request the host to start providing 500mA. This request has to be done through the Default Configuration Pipe of the connection, using “SetConfiguration” USB Device Request. In this configuration, the value of maximum current, in mA, can be set. However, these requests go over the D+ and D- USB pins, since all data goes over those pins. And so, these pins have to be connected to allow the Device to request 500mA.
Now that explains why many times our devices just can’t charge over those USB Wall-Chargers, because they request and expect 500mA charging configuration, but since the USB Wall-Chargers are not “hosts”, and don’t have any micro-Controller or any USB Stack running, they cannot reply to these requests. For that matter, most of them, don’t even have D+ and D- pins at all. And since the device can’t get 500mA, it can decide it can’t charge and stops.

So now, finally the question is, why can an iPod charge on 100mA (I have tried it using a USB Wall-Charger, it works), but the iPhone can’t.
The answer is simple, the phone has a radio for the cellular telecommunications. And cell radios draw huge amounts of currents when they broadcast the data in bursts. So during these bursts, they may sink in the range of 70mA. So if you have a flat battery, and a charger providing only 100mA, and a radio sinking 70mA, only ~30mA is left for the other components including the touch screen and the backlight. Running on low current might cause many issues, especially on displays and touch sensors. So HTC must have decided to only charge the phone, (and in the case of low battery, allow it to boot-up), if 500mA configuration has been successful.
There you go, some interworking of USB and Charging on devices.. or comment on this post, if you have any questions or queries about these things, and I will try my best to answer them..

[TheBundo]

Thanks, Santod. Very good explanation. I think that is in harmony with my overly simplistic explanation, or did I miss something? Sorry if my reading comprehension is a little poor, stayed up all night for the Black Friday stuff to get my wife a TV, then hit the bottle lol. But I think you gave a good technical explanation of my layman's reason, correct?

[santod]

Exactly Bundo. I made, what you clearly stated, into a long drawn out, hard to follow explanation! LOL!

Seriously though, you are correct.

[TheBundo]

Originally Posted by santod

Exactly Bundo. I made, what you clearly stated, into a long drawn out, hard to follow explanation! LOL!

Seriously though, you are correct.

Thanks for telling me, I'm an old tech guy, but don't keep up much any more. I'm 50, and left the computer business as a career in 1990. I was there starting in 1982, and actually wrote commercial software for the Commodore 64, and taught a college class in the early days, on computer tech, both hardware and software. I also was a salesman for the 1st IBM compatible, a brand called Columbia. And I occaisionally get re-interested, and try to catch up a little, but my days of the endless learning and obsolesance of much of my past learning are over. It's too much to keep up with on a regular basis, so I just do it in spurts as needed. I went back to construction, as the changes are incremental, rather than exponential.

Keeping up with all the technology, at least at the highest level, is best left to the younger folks, IMO. I'm becoming content with spurts of catching up to a lessor level.

Thanks, and if this question had come a few days later, I would have probably forgot the answer. I remember stuff from way back better then stuff from last week....

[santod]

No problem man. I always got the impression that you are very intelligent and well informed on much of the technical aspect of what is discussed in these forums. So, don't worry, I know you are an educated guy. I know very well how fast this stuff changes and it's even difficult for some of us younger dudes to keep up as well!

Anyway, I also am in the construction field. I do custom woodworking actually. Windows, doors, cabinets, stairs, counter tops, furniture, etc,....
Enough about that though. Have a great day and know that you are way ahead of the pack especially for your age group. Many people of similar age group, that I know, are very uninformed about computers and technology altogether! So, I'd say you do very well! You've taught me a few things on here, I'm sure of it!

[quarky42]

I don't doubt that the explanation given for why it is doing this is accurate. It is feasible and technically sound.

However, the point of this was: The Touch Pro and the Diamond BOTH charge off of my POWERED USB HUB without having the computer on. My TP2 on the other hand won't charge unless it has the computer on.

I was hoping there was some registry setting, driver, or other tweak that could be done to force the HTC TP2 to charge via the USB Hub in a manner similar to the Diamond and original TP.

This was not a limitation in the other phones I've had. Both the Diamond and the TP could draw between 700-800 mA from my particular powered USB hub when only one device was plugged into it at a time.

It seems like HTC has become "bitchier" about what they will let the phone charge from and have lost some of the versatility in charging that I enjoyed with the other phones. I really like the TP2 a lot, but this is a small disappointment that I wish had a solution. If I run across anything that changes this behavior, I'll be sure to post it back here.