[Q] USB OTG *AND* charging at the same time.

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ssuukk

Senior Member
Hello,

Can you have USB OTG and phone charging at the same time? Or even better: HDMI + USB OTG + charging? Without power the phone discharges fast, not to mention - with HDMI out connected I won't be able to connect external HD with movies... Oh, bother...

Or is there some magic do-it-all dongle?
 

Scruffyo_0

Member
Jun 29, 2011
47
8
Brisbane
Dude, I really hope I'm not misunderstanding, but what is the problem to which 'USB OTG and charging at the same time' is the solution?
Surely you pop your USB stick in, transfer the file and then... stick the charger/HDMI cable back in... and stream wirelessly/over your network?
What were you hoping to achieve? There are several options...
 

PeteEH

Member
Dec 2, 2011
11
4
Technically, the USB-OTG standard includes provisions for handling this.

There are several occasions where you would want to plug an accessory into a USB-OTG port and still be able to hold the state-of-charge in the host device.

The specific document: Battery Charging Specification, rev 1.2
ACA subsection (Accessory Charger Adapter)
The ID_OTG pin acts as an input in this mode of operating, indicating whether or not the host is allowed to charge.

Figure 6-6 shows the typical architecture.
 

whitequark

Member
Aug 12, 2012
5
8
Yes, this is pretty much possible. I have implemented the aforementioned OTG ACA support and got it to CyanogenMod9 upstream. Anything which uses the same kernel (or, if you can cherry-pick changes and compile your own kernels), could use that too. Changeset URL: _ttp://review.cyanogenmod.com/#/c/15850/

You need to use a regular USB OTG cable, but place a 36 KOhm resistor between ID pin and GND, then you should connect GND and Vdd to some power source. I used an MHL adapter which I had no use for, as it had two of three connectors I needed. This setup allows me to watch movies from 2.5" notebook hard drive while simultaneously charging my phone if I plug in a 2A-rated adapter. Note that it's impossible to use 650mA charging rate due to chip restrictions (USB HC is too stupid to understand the direction of current flow, and it reports an over-current condition); you have to settle on 450mA.

If you don't know how to solder, or if you use something else than CyanogenMod9 and cannot compile your own kernels, you are out of luck.

I have tried to find an existing USB OTG ACA dongle, but I was not able to find any. If you will be more lucky than me, you can just use it--my patch is compliant with USB specification and will support any compatible dongle.
 

ZedZardoz

Senior Member
Jan 23, 2012
121
26
San Diego, CA
Yes, this is pretty much possible. I have implemented the aforementioned OTG ACA support and got it to CyanogenMod9 upstream. Anything which uses the same kernel (or, if you can cherry-pick changes and compile your own kernels), could use that too. Changeset URL: _ttp://review.cyanogenmod.com/#/c/15850/

You need to use a regular USB OTG cable, but place a 36 KOhm resistor between ID pin and GND, then you should connect GND and Vdd to some power source. I used an MHL adapter which I had no use for, as it had two of three connectors I needed. This setup allows me to watch movies from 2.5" notebook hard drive while simultaneously charging my phone if I plug in a 2A-rated adapter. Note that it's impossible to use 650mA charging rate due to chip restrictions (USB HC is too stupid to understand the direction of current flow, and it reports an over-current condition); you have to settle on 450mA.

If you don't know how to solder, or if you use something else than CyanogenMod9 and cannot compile your own kernels, you are out of luck.

I have tried to find an existing USB OTG ACA dongle, but I was not able to find any. If you will be more lucky than me, you can just use it--my patch is compliant with USB specification and will support any compatible dongle.

Duh, I read right past this post... 36KOhm on ID <<< got it, now to experiment!
 

burnsn

New member
Jan 19, 2014
3
1
Hello,

I'm new to this forum as i didn't need it yet but now I have a question.

I know this thread is kind of old and I'm not sure if there are still (m)any people using a GT-I9100... though it would be interesting if anyone found a solution on this topic.

I read several threads where people were discussion if charging and OTG is possible at the same time but no one could verify a specific resistor. Actually i tried a resistor valued 124k between GND and ID but it didn't work. I also read about 36k and other values but nothing verified. Could take a while to try several resistors but i really no one knows a solution i'd try this ;)

So just so sum up, i don't need "MHL and charging" or "audio out and charging". The mode i'm looking for is "OTG and charging".

My Goal: a Docking Station with mouse, keyboard, flash drive(s) and charging to remote control my computer with a software like splashtop.

Hopefully anyone has useful information on this, thanks a lot for any kind of support :)
 

burnsn

New member
Jan 19, 2014
3
1

Thanks for your answer!

Today i made my 36k cable, this weekend i should have some time for the kernel patch - hopefully :)

I still have some questions about the kernel as i didn't use any custom ROMs etc on my phone. All I have is a "standard" root kernel without any further changes but root. Need some hours to read into this. What i didn't understand: Do I have to use a specific CM9 or can i use any CM9 (or maybe CM10 or any other CM past 9)?

I wasn't able to get the link working "_ttp://review.cyanogenmod.com/#/c/15850/" when replacing "_" with "h". What can I find on that page?
 

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  • 7
    Yes, this is pretty much possible. I have implemented the aforementioned OTG ACA support and got it to CyanogenMod9 upstream. Anything which uses the same kernel (or, if you can cherry-pick changes and compile your own kernels), could use that too. Changeset URL: _ttp://review.cyanogenmod.com/#/c/15850/

    You need to use a regular USB OTG cable, but place a 36 KOhm resistor between ID pin and GND, then you should connect GND and Vdd to some power source. I used an MHL adapter which I had no use for, as it had two of three connectors I needed. This setup allows me to watch movies from 2.5" notebook hard drive while simultaneously charging my phone if I plug in a 2A-rated adapter. Note that it's impossible to use 650mA charging rate due to chip restrictions (USB HC is too stupid to understand the direction of current flow, and it reports an over-current condition); you have to settle on 450mA.

    If you don't know how to solder, or if you use something else than CyanogenMod9 and cannot compile your own kernels, you are out of luck.

    I have tried to find an existing USB OTG ACA dongle, but I was not able to find any. If you will be more lucky than me, you can just use it--my patch is compliant with USB specification and will support any compatible dongle.
    2
    Technically, the USB-OTG standard includes provisions for handling this.

    There are several occasions where you would want to plug an accessory into a USB-OTG port and still be able to hold the state-of-charge in the host device.

    The specific document: Battery Charging Specification, rev 1.2
    ACA subsection (Accessory Charger Adapter)
    The ID_OTG pin acts as an input in this mode of operating, indicating whether or not the host is allowed to charge.

    Figure 6-6 shows the typical architecture.
    1
    Just taking a guess... maybe he wants to use keyboard and mouse etc with his phone, desktop style

    Sent from my GT-I9100 using XDA App
    1
    Or maybe I just want to play anything from my 1TB HD WITHOUT deciding what should I copy to my phone (which is a waste of time...)

    I wanted to do the same thing but it isn't possible :( . I do however stream from my nas if I don't want to copy stuff to the phone.
    1
    Mirror: _ttps://gitorious.org/replicant/kernel_samsung_smdk4210/commit/c7016a2513abfd522b02633b79d2f21bcb99d4e2

    Thanks again :)

    Today I had some time left to read through many threads and now I know a lot more about kernels. First I was looking for a "CM9 kernel" but I think I understood something wrong when I finally read a CM kernel comes with a CM rom. Actually I don't have a CM rom on my phone, so the necessary steps for me would be:

    - flash cm9
    - compile the kernel you linked
    - flash the kernel

    I found some threads explaining how to compile a kernel from source so I think that shouldn't be a problem for me. Can you confirm these 3 steps to be right? (Or is ACA support in the latest kernel included and doesn't need to be patched again?)

    Another question: If the kernel is the important part to enable ACA support, can I use the code with any rom?