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Timur's Kernel - USB ROM - Most popular thread on Rootzwiki

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OP Timur

Timur

Android Master

Posted 14 January 2013 - 02:16 AM #161

Hi timur,
I dont understand, afaik for make an otg cable pins 4 and 5 must be short without any resisotor,
based on this guide
http://forum.xda-dev...d.php?t=1828032


N7 does not evaluate resistor values between pin 4 and 5. For this reason you should be able to use any OTG adapter - with or without a resistor - as long as pins 4 and 5 are shorted. Other devices may insist on a particular resistor value.
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OP Timur

Timur

Android Master

Posted 14 January 2013 - 05:28 AM #162

... wondered if perhaps the rest of the circuit might help at all.


I don't think that page is very helpful here. This dude also needs a little more Jonathan Ive in what he does :)

If a USB hub is required, there are really two simple options. Both can be implemented using the most basic OTG + side-charging Y-cable. And without any soldering:

Posted Image

Both options allow your N7 to take the role of a USB host, while being charged at the same time. Both options should allow you to pull power and let your N7 fall into deep sleep (using my FI kernel) or continue in OTG mode (when using my default kernel for mobile use). I think I like option 1 a little better. You find my kernels here http://mehrvarz.gith...l-download-page

Edited by Timur, 14 January 2013 - 05:47 AM.

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Kuchar09

Kuchar09

Android Lover

  • 137 posts

Posted 14 January 2013 - 07:07 AM #163

I see. You are switching both power supplies on and off at the same time, thus preventing the issue I describe above. But why use two power supplies, at all? My advise would be to use one good power supply (3A or more) to operate N7 + hub in parallel. This should cover your hub + 4 slave devices and your N7 consuming 500mA or more (which I don't think it will). Doing so will most likely also solve your static issue. And yes, 8% drop of charge over night is a sure sign, some configuration or some piece of software is preventing your N7 from going to deep sleep.

I had the static issue before I installed it in my car when there was just one power source. With just the otg y charge cable and DAC I had static issues using the stock charger in my house.
I used separate power sources so I could wire up a button to charge the tablet over night in case the battery got too low and didn't want my hub to turn on. I can wire them to the same plug, I have a 2A DC plug I use for my hub that has two ports (each port 1A) and see if it makes a difference tho.
I also have a 1 amp port that has constant power that I could hook my hub to, just not sure I wanted everything on my hub having power over night.
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dlbogdan

dlbogdan

Member

  • 44 posts

Posted 14 January 2013 - 08:13 AM #164

so far perfect kernel (the Fixed Installation one). Couldn't find any bugs.
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bru

bru

Member

  • 18 posts

Posted 14 January 2013 - 10:54 AM #165

Does anyone else have any issues with static sounding audio coming from your DAC every now n then?
Now that I have this installed in my car it happens about once a day, to fix it I just shut off the car and and then turn it back on basically reconnecting the DAC and then its fixed. I believe I had this issue with previous kernels when trying to set everything up for my car install so I don't think its a specific use with your kernel but more something with the DAC programming overall. I could be completely wrong tho


I heard some artifacts from the DAC sometimes (not installed in car yet). Seemed to happen when I was touching stuff and moving around through the OS. If I leave it alone I don't hear anything. Would be interested to know what causes this.
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iceman_jkh

iceman_jkh

Android Lover

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Posted 14 January 2013 - 01:18 PM #166

If a USB hub is required, there are really two simple options. Both can be implemented using the most basic OTG + side-charging Y-cable. And without any soldering:
...
Both options allow your N7 to take the role of a USB host, while being charged at the same time. Both options should allow you to pull power and let your N7 fall into deep sleep (using my FI kernel) or continue in OTG mode (when using my default kernel for mobile use). I think I like option 1 a little better. You find my kernels here http://mehrvarz.gith...l-download-page

Thanks. That drawing helps explain it even better. Perhaps it would be worthwhile adding that pic that to your blog comments (where you discuss the 2 hub powering options)?
In Option 1, does the connection from the N7 (the one paralleled with +5V) need to go into any particular connection on the hub (ie: specifically, does it need to go into the upstream port as it appears to be drawn in your picture)? The reason I ask, if connecting to one of the 'downstream' ports, might there be some internal current limiting circuitry that would prevent more than 500mA passing through a particular port, and therefore limiting the charge current available to other devices.
Perhaps it depends on the hub itself?

Bru:
Users over at head-fi commenting on issues with N7 audio noise/static when using touch screen.
http://www.head-fi.o...blet-tegra-3/90
They haven't commented for a few weeks, but a solution may eventually be posted/found in that thread.

Thanks.
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millab

millab

Member

  • 16 posts

Posted 14 January 2013 - 04:30 PM #167

Hey Timur, I wanted to give you an update.

I have been fiddling with my in-car setup over the last few days and have decided to permanently connect the power to both tablet and hub. Tasker will be used to trigger the screen turning on and off when it detects my car's bluetooth connection. I am using your fixed kernel and it is all looking stable at the moment. I will be commencing stability testing in the next day or two for about a week, so I can also let you know if there are issues with power draw on the car battery.


My setup doesn't utilise a DAC as I am using the A2DP bluetooth head unit that came standard in my car. I have moved the head unit back inside the dash and I am placing the tablet between the head unit and the cutout in the dash. The advantages of this are:
  • very high sound quality through bluetooth (in my car anyway)
  • Steering wheel controls work with tablet
  • No need for an amplifier
  • Tasker triggers from bluetooth connection being made with the car
  • Can still listen to radio, CD (using steering wheel controls only, as can't access the buttons or see the screen on the head unit)
  • Can have phone and tablet connected at the same time (pauses tablet when phone gets a call and directs phone audio for the call)

Edited by millab, 14 January 2013 - 04:31 PM.

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iceman_jkh

iceman_jkh

Android Lover

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Posted 14 January 2013 - 06:06 PM #168

Millab,
How are you doing 6?
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millab

millab

Member

  • 16 posts

Posted 14 January 2013 - 11:38 PM #169

Millab,
How are you doing 6?

My head unit allows multiple paired devices. When I pair my phone, it registers as both handsfree and audio, then I disable the audio option in BT connection settings on the phone, and then pair the tablet. It works perfectly :)
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iceman_jkh

iceman_jkh

Android Lover

  • 150 posts

Posted 15 January 2013 - 12:51 AM #170

Ah, gotcha.
I'll be running only the N7 (non-3G) as the media player in my car. It will auto-tether via wifi or BT (undecided) to my Samsung Galaxy S3 when I'm in the car.
I've looked at AUTOREMOTE (which can be run as a module for TASKER as the main app) to send a push msg to the N7 when my phone receives an incoming call (or starts to dial out). This push msg goes to the N7 where I use tasker to pause the music for the duration of the call (and resume playing once the phone is back on the hook). This works pretty well (during benchtop testing) with a Wifi + fast internet connection (eg: ADSL2+/4G/LTE) and is able to pause the music on the N7 in under 2 seconds. Trouble is, when I'm in the car, I'm only on a 3G network (and sometimes in a carpark basement with no reception), so this notification takes 7+ seconds to arrive, defeating the purpose - I might as well pause the N7 manually.

I've started a thread with the Autoremote dev about a direct device to device connection (via Wifi/BT, that works without internet connectivity) but it's not currently on his priority list (not enough demand).
Thread: https://groups.google.com/forum/#!topic/joaomgcd/pUQIyvmbEHM

If you're interested in the ability to directly communicate between android devices (ie: push notifications) without Wifi/BT, please show your support in my thread (linked above). This kind of feature could be used for SO much more than just this application!
Also, if anyone knows of any other methods for syncing a pause/mute between their phone and the N7 (via Wifi/BT) I'm happy to hear it.
Cheers
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