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Mod Type:: ROM

Difficulty:: Very Easy

Mod Status:: Stable

Apply In:: CWM Recovery

Requires Root:: Yes

Source::
n7usb.png


USB ROM for Nexus 7 2012

Timur's kernel + extended USB host functionality + fast charging in one great ROM.

+++ This project has been discontinued in August 2013 +++

+++ Download images have been offered for another 12 month, until September 28 2014 +++

Testimonials:

"I can't remember the last time I was this excited/happy to have something like this working - especially something as cool as a USB DAC on the N7 for my car install!" - iceman_jkh

"FREAKING AWESOME!! thank you thank you thank you so much!" - bbennett2

"THANK YOU! Your thread was _the_ reason I purchased my N7. Just seeing that big screen in my truck is so satisfying!" - joltman

"Loving this ROM and am having no problems so far" - Kuchar09

"Hot plugging also works perfectly. This is awesome!" - Agent_Cooper

"I'm really enjoying the install and it is by far a mandatory change for anyone with a true fixed install." - Kseiter

"This ROM rocks!!! I love it!" - Jon102034050

"an absolutely brilliant rom/kernel/solution that undoubtably expands the N7's usefulness from low to unlimited!" - bjornh

"I have been testing in the multirom enviroment, and everything looks wonderful. The kernel is also used on several different roms I am running, and all are correctly using the host mode charging, including stock 4.2.2." - rebel1699

"With firm sleep on, my battery lost no percentage in the last 10 hours. Rather amazing." - RED ZMAN

"I've been using this ROM a lot and love it. I'm designing my own custom dashboard for my car and this ROM is the only thing making the N7 useful." - eric_fri

"This is one of the most awesome tweaks for any device I have ever owned." - ppmcbiggs

Info + release notes: http://mehrvarz.gith.../nexus-7-usbrom

Dashboard gallery: https://timur.mobi/dashboard.html

To search this thread, use this link: http://www.google.co...=1&filter=0
...and add individual search items to the query.

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Timur's kernel (standalone)

This kernel enables USB host mode functionality on the Nexus 7 and allow you to operate multiple USB slave devices and charge your tablet and all slave devices at the same time.

Some severe host mode related issues, found in the stock kernel, have been fixed. For the first time you can use USB slave devices through sudden power loss and deep sleep situations. Robust USB host mode operations can take Android customization to all new levels. What you do with it, is limited only by your imagination. One of the more obvious things you can do, is to use your Nexus 7 together with a USB DAC in a car dash setup. Timur's kernel enables USB Audio. So go ahead and create your audiophile ubersound fixed installation setup.

Timur's kernel is available for both JB 4.2.x and CM 10.1.

Latest releases:

CyanogenMod 10.1
2013-04-21 kernel --- NEW
2013-01-29 kernel for fixed installation

Stock Android 4.2.x
2013-01-24 kernel
2013-01-29 kernel for fixed installation

More info
http://mehrvarz.gith...nagement-nexus7

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User projects
Ion - Another Android Vette build http://forums.corvet...ild-thread.html
jmcguire525's Ultimate car stereo http://rootzwiki.com...ate-car-stereo/
Kookie's In-Dash Project: http://rootzwiki.com...in-dash-project
Kuchar09's N7 clean car install with backup cam: http://forum.xda-dev...d.php?t=2113259
naiku's 2006 Audi A4 - In Dash Install http://rootzwiki.com...in-dash-install

Interesting posts
MetalMan about the advantages of fast charging: http://rootzwiki.com...40#entry1066538
diba320 says excellent product: http://rootzwiki.com...60#entry1072112
Timur talking about deep sleep: http://rootzwiki.com...10#entry1078694
The Guz being happy about USB audio: http://rootzwiki.com...10#entry1078861
Timur pointing out how the FI kernel works: http://rootzwiki.com...30#entry1080163
dlbogdan thinks the FI kernel is perfect: http://rootzwiki.com...60#entry1081616
MetalMan needs it to work smoothly (which it does) in his lunch break: http://rootzwiki.com...80#entry1083294
A destroyed USB port is coming back to life: http://rootzwiki.com...90#entry1083602
Rezl building a N7 roboter: http://rootzwiki.com...00#entry1083874
b0bd is solving the power loss audio pause issue: http://rootzwiki.com...30#entry1086236
dcplaya is very interested in HD radio: http://rootzwiki.com...40#entry1086492
joltman want's this submitted to CM: http://rootzwiki.com...70#entry1087336
iceman_jkh wants DAB+ on the N7: http://rootzwiki.com...90#entry1088030
Timur showing off DVBT + USB audio on the N7: http://rootzwiki.com...90#entry1088062
diba320 confirms N7 3G is supported: http://rootzwiki.com...00#entry1088458
dcplaya finds b0bd's grabfocus solution wonderful: http://rootzwiki.com...30#entry1089524
AnyHertz couldn't find any issues: http://rootzwiki.com...70#entry1089997
Keiththevp about running without a battery: http://rootzwiki.com...70#entry1090181
iceman_jkh's list of media apps: http://rootzwiki.com...80#entry1090293
Timur's host to peripheral mode switch: http://rootzwiki.com...80#entry1090420
Timur on how to log deep sleep: http://rootzwiki.com...90#entry1090747
Kookie_Monster getting revenge: http://rootzwiki.com...00#entry1091018
Kuchar09's backup cam video: http://rootzwiki.com...30#entry1091844
nexus-fan's momentary switches and PC mode\OTG cable: http://rootzwiki.com...40#entry1092248
b0bd linking to 5-wire micro USB extension cables: http://rootzwiki.com...50#entry1092368
jayman488 about car home wifi sync: http://rootzwiki.com...70#entry1092652
Kuchar09's SDR radio video: http://rootzwiki.com...80#entry1092948
b0bd's HD-radio video: http://rootzwiki.com...00#entry1093159
millab pointing out N7's heat resistance: http://rootzwiki.com...00#entry1093217
iceman_jkh on what DAC to buy: http://rootzwiki.com...40#entry1094700
AnyHertz's FTDI info: http://rootzwiki.com...60#entry1095004
1st release of USB ROM http://rootzwiki.com...00#entry1096212
2nd release of USB ROM http://rootzwiki.com...20#entry1099688

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Team EOS got their EOS 4 Nightlies (ROM) to the point where I felt comfortable swapping over to 4.2.1 (was still on 4.1.2 until about two hours ago!). So I of course also flashed your latest kernel for fixed installation. At this point I let it sleep for a bit after pulling the power from my Y-cable (I have a Tasker routine which essentially stops the music, turns the screen off, turns off BT and wifi, etc). And upon replugging the power the audio resumed just fine!

However: whenever I have power plugged in without the charging cord plugged directly into the N7 (data pins shorted) the tablet only charges at USB speeds. Do you have to enable fast charging in the kernel? Or is there a script we can toggle for fast charging?

Thanks for all your hard work! I too am interested in a Paypal donate link for you :)
 

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Discussion Starter · #7 ·
And upon replugging the power the audio resumed just fine!

However: whenever I have power plugged in without the charging cord plugged directly into the N7 (data pins shorted) the tablet only charges at USB speeds. Do you have to enable fast charging in the kernel? Or is there a script we can toggle for fast charging?
The original N7 charger has the data pins shorted internally, this way signalling to the device being charged: yes, it is OK for you to draw more than 0.5A. And the N7 will do so. But with a Y-adapter connected to the N7, this information does not get delivered anymore. Or rather, the N7 has no way to detect it. Take a look at this diagram and you will see why: https://sites.google.com/site/sonicboomworld/_/rsrc/1345753009582/my-projects/otg-diagrams/Y_OTG_CABLE.png
If the Y-cable *would* wire through the two middle pins (Data +/-) towards the charger, that would make data communication between host and slave impossible, as soon as you have the original N7 charger connect. This is why, in host mode, N7 will only charge at USB speeds.
 

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The original N7 charger has the data pins shorted internally, this way signalling to the device being charged: yes, it is OK for you to draw more than 0.5A. And the N7 will do so. But with a Y-adapter connected to the N7, this information does not get delivered anymore. Or rather, the N7 has no way to detect it. Take a look at this diagram and you will see why: https://sites.google...Y_OTG_CABLE.png
If the Y-cable *would* wire through the two middle pins (Data +/-) towards the charger, that would make data communication between host and slave impossible, as soon as you have the original N7 charger connect. This is why, in host mode, N7 will only charge at USB speeds.
Right, I understand that. Your 4.1.2 kernel forced charging at AC speed while in OTG host mode, so that's why I thought to bring it up and ask if it could be changed or if there is some setting or script I can change on my N7. I've found the USB charging rate to be insufficient at maintaining charge just simply with the screen + wifi + BT on.
 

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I have been using this for 3 days and my battery level stays at 100% once its reached and Im running bluetooth,wifi,gps.
It using only drops a couple % over night when in deep sleep and recovers that in about 10 mins of driving.
Its doesnt show AC charging or usb charging in my battery tab but I assume its charging whatever my charger puts out minus the usb usage.
I have a 2.1 amp charger,maybe yours is a lower output.
 

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I have been using this for 3 days and my battery level stays at 100% once its reached and Im running bluetooth,wifi,gps.
It using only drops a couple % over night when in deep sleep and recovers that in about 10 mins of driving.
Its doesnt show AC charging or usb charging in my battery tab but I assume its charging whatever my charger puts out minus the usb usage.
I have a 2.1 amp charger,maybe yours is a lower output.
Right now my testing is with the charger that came with the N7, which is rated at 2.0A. On the battery screen it says "XX% - Charging (USB)". Plugging the N7 charger directly in and it will say "XX% - Charging (AC)". My question only revolves around how to enable/force fast charging.
 

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Discussion Starter · #13 ·
I've found the USB charging rate to be insufficient at maintaining charge just simply with the screen + wifi + BT on.
My N7 stays at "100% full" all the time, with screen + wifi + BT turned on. After an over night sleep (no power supplied), the battery goes from 95% to 100% in just a few minutes. Rather than trying to supply more power, you should try to find the root cause of the issue. A single misbehaving app can easily ruin all power management. Does your tablet run warm? What's on top of your power consumer list?

If you urgently need to activate fast charging, with the OTG adapter being connected to the tablet, you could try to short the Data pins using a manual switch. I don't think it will, but, you never know, this *might* harm your devices.
 

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Oh...they're talking about 'physical' installation duh....haha I was wondering how it differed from a regular kernel installation and why I never heard of it......

Sent from my Nexus 7 using Tapatalk HD
 

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Oh...they're talking about 'physical' installation duh....haha I was wondering how it differed from a regular kernel installation and why I never heard of it......
OTG host mode is by definition just a temporary endeavor. Whatever you do in OTG mode, you have to stop doing it after a while and go charging. My kernel allows you to use USB slave devices AND to keep your tablet charged at the same time. So you can keep using your USB devices as long as you want.

The default (or mobile) variant of the kernel provides USB host mode + charging functionality, but will switch to OTG mode, whenever external power goes away. When you pull the OTG adapter, when using the mobile variant, your N7 will behave just like a normal Nexus 7. It's usually a good idea to provide new functionality, without taking away existing functionality. But there are cases where this is not true. The "fixed installation" variant takes OTG functionality away. It never sends power down to slave devices. This allows you to more easily put your tablet to deep sleep mode, when external power goes away. Your tablet will then keep it's charge over long periods of times and it will be ready to immediately serve you, as soon as external power comes back. And because both variants are available for Android and CM, there is a total of four kernel variants.

Note: I just updated the two Android 4.2.x variants (now: 2012-12-23) in order to fix an infrequent crashing issue. The two CM 10.1 variants (2012-12-19) are not affected by this and have not been updated.

Edit: @farhanito, CIFS is enabled in all variants. Can you elaborate on your use case a bit?
 

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@Timur,
Well, this has been a well known problem on N7 since 4.2
Also happens with other kernel that supporting cifs as well. Something Google did

Using CIFSManager app, it says mounted, but shows empty folder on any file manager apps.

Tried mounting manually using terminal emulator, mounted, but still inaccessible with other apps.

Nexus 10 also have the same problem...
http://forum.xda-developers.com/showthread.php?p=34400889

Sent from my Nexus 7 using Tapatalk 2
 

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Hi Timur,

Thank you for all your work!

[background=rgb(245, 245, 245)]I plan to install my Nexus 7 in my car (like many people). I'm planning on using a powered USB hub with a DAC, harddrive, external bluetooth GPS, HID type keyboard that will utilize car steering controls, and so forth.[/background]

[background=rgb(245, 245, 245)]The USB hub I'm planning on using will have a 20 minute shut off delay so that when I shutoff the car, it will still have power for 20 minutes. Theoretically, I was planning on having the power to the N7 tied to the ignition. I was doing this so that all the devices would still function for a while after the car was off. For example, the GPS wouldn't lose its lock at the gas station, or when I pull into my garage, I could kick off an rsync to make sure my music collection is up to date. [/background]

[background=rgb(245, 245, 245)]When I simulated this outside of the car in testing, the USB devices did not react well when the power was cut to the N7. The N7 didn't seem to be able to charge after (or at least I saw no icon for it) and the devices flicker, but seem to come back sort of okay (external HD gets detected as sdb1 instead of sda1. Annoying but probably fixable).[/background]

[background=rgb(245, 245, 245)]I've tried both kernels and am trying to understand what behaviors currently exist in each, and if there is anything I can do to leverage what work you've already done.[/background]
[background=rgb(245, 245, 245)]I'm trying to avoid running the N7 off of a hot wire in the car (always on, draining battery). It might be feasible I guess. I've seen this device last well over a week in airplane mode.[/background]
 
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