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Can you charge & USB Host mode simultaneously?

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ddxfish

ddxfish

Average Android

Posted 20 November 2012 - 04:11 PM #131

They make a special cable for this called an MHL Cable

http://www.sfcable.c...CFcXb4AodEmcARg

It has a micro usb to HDMI/USB

It allows charging, HDMI video, and USB connectivity.
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Nexus 7, Motorola Droid 3, Samsung Galaxy Tab 2 7.0

kevincat3556

kevincat3556

Android Lover

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Posted 20 November 2012 - 04:18 PM #132

They make a special cable for this called an MHL Cable

http://www.sfcable.c...CFcXb4AodEmcARg

It has a micro usb to HDMI/USB

It allows charging, HDMI video, and USB connectivity.


I thought the N7 didn't have the hardware for MHL? and my nexus drains when plugged into the TV... But you guys should make what i did. ill rip it apart and take pictures in a while.
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MetalMan

MetalMan

Android Lover

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Posted 20 November 2012 - 07:06 PM #133

Timur

Someone else has asked this already but it was never answered. Is the a way to make a new img where it has USB OTG + Charging with a Y-Cable as well as normal USB OTG when you don't want to charge? As it is right now normal OTG does not work only with a charging cable. ie. In other words, to have the kernel auto-detects if there is a charger attached via a y-cable and uses it to power the external device and charge, ONLY if it's found.

Same as here
http://forum.xda-dev...50&postcount=70


The fifth pin on the USB on the device(nexus 7 or gnexus) is for OTG. Connect the fifth pin to ground and the device goes into host mode. you could run a small switch from the micro USB plug and put it outside of the cable i guess. When i get home, ill draw some stuff out


Yes. I made my own OTG cable from a chopped up Motorola charger for my GNexus. Same thing applies here. The extra 'sense' pin, is usually unused. so just connect it to a little toggle switch and make it togglable. lol. sorry. hard to concentrate here, the teacher is INSANE!


what i mean is, take the sense pin, and instead of just shorting it out, run it outside of the plug and you can toggle OTG mode WITHOUT having to take the cable out! lol. it actually charges my power-hungry nexus with a controller and HDD hooked up playing GTA3, so it should DEFINITELY charge the Nexus 7, which i will be getting for christmas. i can do more testing when i get home tomorrow.


kevincat3556: You're misunderstanding the question that GoldMembr posed. He asked about toggling between OTG + charging (charger powers any USB peripherals) and regular OTG (Nexus 7 powers the USB peripherals). This has nothing to do with the sense pin, because in both configurations the sense pin must be shorted to ground.

What you're talking about, with toggling the sense pin, would be switching between OTG host mode and fast charge mode.
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GoldMembr

GoldMembr

Average Android

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Posted 20 November 2012 - 10:51 PM #134

kevincat3556: You're misunderstanding the question that GoldMembr posed. He asked about toggling between OTG + charging (charger powers any USB peripherals) and regular OTG (Nexus 7 powers the USB peripherals). This has nothing to do with the sense pin, because in both configurations the sense pin must be shorted to ground.

What you're talking about, with toggling the sense pin, would be switching between OTG host mode and fast charge mode.


Yes exactly. As it is right now it kind of stinks having to power every single USB device by external charger alone. I think people want to charge only when they have to . I don't think it's good for the battery to always be charging either. Even for a game pad you have to always have external charger so it kind of defeats the purpose if there isn't a way for the device to be able to distinguish between internaly powering USB when there isn't an external source detected. I'm hoping Timur may have a solution to the problem. Don't get me wrong Charging + USB OTG is awsome but not at the expense of normal operation as well, at least for my needs anyway.

Edited by GoldMembr, 21 November 2012 - 04:45 AM.

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Timur

Timur

Android Master

Posted 21 November 2012 - 08:06 AM #135

Timur, will your boot image work on 4.2? I suspect It will not but thought id ask anyway.


Well, it does. Referenced below is a modified Nexus 7 (grouper/wifi) kernel for stock JB 4.2. It is based on 3.1.10-gb980927 and includes the known changes:
- externally powered USB host mode operations (patch 1)
- charging in USB host mode (patch 2)
- enabled USB sound + CIFS
In short: functionality should be identical in both variants.


JB4.2: https://github.com/m...-2012-11-21.img
CM10: https://github.com/m...-2012-11-15.img



Backup your stuff. Use at your own risk.
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GoldMembr

GoldMembr

Average Android

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Posted 21 November 2012 - 12:46 PM #136

Well, it does. Referenced below is a modified Nexus 7 (grouper/wifi) kernel for stock JB 4.2. It is based on 3.1.10-gb980927 and includes the known changes:
- externally powered USB host mode operations (patch 1)
- charging in USB host mode (patch 2)
- enabled USB sound + CIFS
In short: functionality should be identical in both variants.


JB4.2: https://github.com/m...-2012-11-21.img
CM10: https://github.com/m...-2012-11-15.img



Backup your stuff. Use at your own risk.


Thanks for the new images. So i guess there is no way to have it distinguish between external and internal power then?
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dmexs

dmexs

Member

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Posted 22 November 2012 - 04:58 AM #137

Timur, which USB DAC are you using? The Behringer UCA222 looks pretty nice right now. I didn't see the need for one initially, but I'm starting to feel like the audio in my car isn't as clean as it could be.

Thanks again for all your hard work!
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Timur

Timur

Android Master

Posted 22 November 2012 - 05:38 PM #138

jmcguire525, on 18 November 2012 - 02:54 PM, said:
sometimes it takes up to 10 mins to detect the DAC

Now I see why you want to keep your DAC powered all the time. Please note that my cheapo DAC does not do that. I have to stop/start a song, too. But it always plays after a second or two. You might want to consider testing another DAC?


I think I know what is going on here. IF I unplug my DAC, while audio is streaming to it, I do afterwards get some small delays. Something in the area of up to 5 or 10 seconds. I normally pause playback before I unplug the DAC, in which case there are no delays (after reconnecting). Your much longer delays may have something to do with the amount of memory your DAC provides for buffering. Maybe you can verify this analysis?

Edit: @dmexs: Can't really help you with this. I'm currently using a very basic "DAC" the size of a 4GB flash drive. From the usbaudio driver point of view, it looks just like the big audiophile devices. (I will probably go the Behringer route as well soon.)

Edited by Timur, 22 November 2012 - 06:06 PM.

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Timur

Timur

Android Master

Posted 23 November 2012 - 09:06 AM #139

...to have the kernel auto-detects if there is a charger attached via a y-cable and uses it to power the external device and charge, ONLY if it's found.


Hi GoldMembr,
yes it is possible. More on this coming very shortly.

Here a little survey for you Nexus 7 owners: on what system would you rather see USB host mode updates becoming available?

a. JB 4.1.x stock
b. JB 4.2 stock
c. CM10
d. CM10.1

Edit: damn smilies B)

Edited by Timur, 23 November 2012 - 09:07 AM.

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RWNube

RWNube

Android Beginner

  • 81 posts

Posted 23 November 2012 - 12:07 PM #140

I am very happy to report that I now have USB OTG + Charging enabled with CIFS shares mounting properly. Thanks to Timur, and possibly others, I now can use the ROM of my choice (running Cookie's 'N Cream) and still have USB OTG + Charging + CIFS. I flashed the kernel found in post 120 by Timur.
The USB Audio settings stick until reboot, so I can unplug and plug the DAC, tablet, and charging cable any number of times and USB Audio still works.

Does anybody know how I can convert that IMG kernel file to a flashable zip so I can swap back and forth between Trinity kernel and this USB OTG+Charge kernel in Recovery instead of fastboot via computer?
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