mzilvar

iTrader: (3)

Hmmm, thats odd.

I didn't have any problems when I wasn't using USB. I doubt the fast charging in USB-ROM is going to help you. It's designed there to allow the tablet to fetch more power to power USB devices since once it's placed in OTG mode by the 5-pin USB OTG cable the stock kernel prevents it from doing so to prevent battery damage. Something like that, and normally it doesn't charge in OTG. You don't have these issues though.

Do you have any other 5V USB adapters? My guess is your USB adapter isn't providing enough amperage?

Did you make sure you're on the right port on it? One port provides 2.1A and the other 1A normally.

Do you have any other devices plugged into the same USB charger on a second port? If so try unplugging the second device.

Other than that I'd check out your settings on the tablet, display brightness, etc but that shouldn't be an issue at all.

I know some of the USB car chargers will charge the tablet at the USB rate, when the tablet is plugged into one of these the normal draw is only 500mA. When plugged in does it show 'Charging USB' or 'Charging AC' ? Mine always shows 'Charging AC' even though it's plugged into a USB car charger.

If it shows 'Charging USB' I'm going to say it's probably the USB car charger (basically just a power supply, converts your car's 12-14V to 5V @ a specified amperage).

I suppose a second test to completely isolate it would be..

Plug in an extension cord to an outlet & run it to your car
Plug in your AC Nexus charger to the extension cord
Plug the USB cable into the AC Nexus charger on the cord

Now does the tablet charge while it's running?

If so it must be the power supply you're using in the car. This would prove your Nexus' battery and internal power supply to be good.

If not then something could be up with your tablet or USB cable I might guess. Not much to go bad on a cable though other than a poor connection, maybe a bad solder or partially broken wire. Those wires are tiny.

Ho9984

USB cable should be fine, im able to transfer data back and forth with no issue. It shows charging AC.

I'll try the enxtension cord idea. but if i remembered correctly from before, it was always a slow charging device.

Thanks. I'll finish everything up this weekend hopefully and post pictures.

I wired the outlet in my center console to a switch to the ACC and constant power in the case for those rare instances where i want to try and charge while engine is off. Hope that doesnt drain my car battery too much. Will only use it in emergency situation where i might need to charge the tablet.

mzilvar

iTrader: (3)

It shouldn't be too bad on your battery just charging the N7 with the car off. I use mine sometimes with my key in the ACC position since power is provided to the 12V socket in the center console and where the cubbies were in this position.

Usually just if I was troubleshooting the bluetooth a bit or setting something up on the tablet.

Also when I referred to a possibly bad solder I meant on the +5V wire on the USB cable, that one could be partially broken or something on the solder or elsewhere and it wouldn't be able to draw the full amperage.

My bet is on the USB charger you're using though, it should be able to draw plenty of juice to charge the N7 while you're driving and not drain at all when its off.

For reference my battery is at 100% all of the time, might dip to like 99% after a day or two of not driving though.

When I had the problem you described the N7 was still drawing power when it was in it's 'sleep' mode where all the interfaces were disabled, in my case I'm sure it was my USB hub. In that case the power supply didn't supply enough juice to really charge the N7 while the car was on, most of my trips were relatively short though and it would only charge maybe a few percent, then the drain would happen while the car was off.

I would verify the settings you're using in tasker and make sure all your radio interfaces are shut off and the screen turns off when power is removed. Airplane mode and the screen off are the big ones that will save your battery.

You could also look in your battery stats and see whats using your battery to determine if its an app or something that isn't closing and is continuing to process something and use up an excessive amount of resources draining your battery.

Have to remember using tasker the way I outlined the tablet is actually on 100% of the time, and I was just shutting down interfaces to prevent the battery draw. So if an app was running it'll keep running unless there is something to stop it.

USB-ROM does have the power management options built into it now, so that could help you. My tablet goes into 'deep sleep' mode in 3 seconds of having power removed now with USB-ROM and turns on the display and is ready immediately upon application of power.

Ho9984

I was able to install the "cm grouper" and after that google_apps. Took me longer than i wanted to using wugfresh tool kit.

You say all that power management and deep sleep happens automatically? But when i turn my car off and power is no longer connected, how do it get it to automatically go in to deep sleep?

mzilvar

iTrader: (3)

I'm not familiar with those tools, I always flash directly from recovery after wiping.

All you should have to do for it to go to sleep is remove power from the USB cable.

Check in your System Settings, make sure you're in 'FI Mode' (for Fixed Installations).

Also may want to check 'Landscape Mode' somewhere in the system settings and give it a reboot.

If it's already in the bezel an easy way to reboot is:

- Install a terminal emulator
- Start terminal emulator
- Type 'SU' & press enter
- Grant Root permissions if prompted
- Type 'Reboot' & press enter

This way you don't have to touch the power button at all if its inaccessible.

Check that this one:

cm-10.1-20130506-USBROM-grouper.zip WiFi 4.2.2

Tilapia is for the 3G (cell-plan) tablet

is the one you installed, available here:

http://mehrvarz.github.io/nexus-7-usbrom/

towards the bottom

Is your tablet unlocked? I'm pretty sure you need to be bootloader unlocked before you go over to USB-ROM. Custom recovery should be first once you unlock so you can make a nandroid backup to revert back if needed. There were some extra steps I had to take to prevent the N7 from reverting back to stock recovery on reboot that were posted on XDA somewhere. I'll see if I can find it again.

mzilvar

iTrader: (3)

Here's the toolkit I used:

http://forum.xda-developers.com/show....php?t=1809195

It has steps in the second post to get custom recovery to stick after reboot as well.

Some pics of FI mode enabled. Mine is forced 'ON' because I have a hub plugged in I think. Not sure exactly why but I know I can't switch out of FI mode.


I need to clean my car, dusty

Ho9984

Yeah, i also i have my FI mode enabled. But it doesnt wake up or go into sleep when power i turn on and off power. Can you post a pick in your about screen. To see the kernel and rom info. Im still not positive if i have everything correctly installed.

Im not sure if i need to install this

http://mehrvarz.github.io/nexus-7-kernel-download-page/

and base on this page
http://mehrvarz.github.io/nexus-7-usbrom/

i dont have the "System" section, with firm sleep option and such

mzilvar

iTrader: (3)

That's odd.

I'd check the status of your tablet being bootloader unlocked & rooted.

Then I'd do a wipe, factory data reset and install the zip from SD card using custom recovery.

Make sure to wipe the dalvik and cache before installing from SD.

Here's some pics.

The kernel is actually a part of the USB-ROM zip file, so you shouldn't have to flash any of the kernels listed on the other page. It should write everything to the appropriate partitions during flash.

I'm using touch recovery since it makes the most sense to be able to enter recovery through an app (ROM Manager, reboot to recovery) and then just use touch on the tablet so you don't need to access the volume / power switches on the tablet.

Ho9984

Is it possible because im not using a USB hub? Mine is still just a direct USB to the charger. I tried everything, and it wont wake up/go to sleep on its own.

mzilvar

iTrader: (3)

It shouldn't matter if its in FI mode.

I just checked mine, disconnected the USB hub, rebooted and it still works only difference mine has an OTG cable still plugged into it.

Check your root permissions, do you still have root access ? Can you grant root to apps?

Also check in your apps you should have one called 'PowerEvntMgr' with an android icon, its spelled something like that.

Try opening it up, it should just give you a brief description of what it does and thats it.

To check superuser on USB-ROM it's in the System settings under '# Superuser' or something like that.

I guess worst case you could post your question on the rootzwiki forum for USB-ROM or read around there and see if anyone else is having the same issue you are.

Only other thing I can think of if everything is loaded properly is the OTG cable, if it has to have one plugged in to use powereventmgr but I don't think thats the case.

Did you turn off any tasker profiles? I have mine all off at this point.

mzilvar

iTrader: (3)

Did you do this?

If you are NOT currently running CM 10.1 or USB ROM, you need to first do a factory reset (wipe data partition). This will remove all your apps and custom settings. Afterwards you may want to install GApps for 10.1.x http://wiki.rootzwiki.com/Google_Apps. (I do not use this. And don't know anything about it.)

Before installing USB-ROM from stock?

Ho9984

when you say "CM 10.1" do you mean CyanogenMod 10.1 kernel?

I pretty much just went from a bone stock nexus 7, unlock and root the device. And then installed the "grouper". I dont see the power management app you're referring to.

I guess what i really need is instructions if i were to start with a fresh/factory Nexus 7.

Im sorry for all the questions. trying to get this thing going has been frustrating.

mzilvar

iTrader: (3)

I don't mean the kernel, it's included in the USB-ROM zip that I referenced.

If the power management app isn't there then thats your problem.

For reference USB-ROM is a CM10.1 based ROM, just modified to add the kernel that supports USB functionality and all the USB features in the ROM itself. Everything is included in that SINGLE zip file with the exception of GAPPs. You'll find this to be common with these ROMs, they're open-source and as a result they can not legally package GAPPs with the ROM. So GAPPs has to be downloaded separately if you want them. FYI (GAPPS = Google Apps, I.E. Google Navigator, play store, etc.)

Sounds like there was a problem with your flash, did you flash from recovery or use a utility?

I really don't like using utilities to flash, I normally do it directly from recovery and utilize fastboot to do wipes (quick & easy once you're familiar).

Ohh and you should've done the trick to enable the developer options and turn on 'USB Debugging' I'd just leave it on all of the time. Have you already done that? If not..

- Go to system settings
- Go to about phone
- Scroll to the bottom and tap on the build number 7 times to enable it, you should start to get some prompts as a count-down
- Go into the newly opened dev options menu
- Enable USB Debugging

Do you have custom recovery sticking ? If you reboot into recovery is it still stock or is it the custom one you flashed?

If you have custom recovery loaded and it sticks I'd do the following

BIG ONE HERE - before you start flashing make sure you're on reliable AC POWER, you don't want anything going out when you're flashing.

If you've got custom recovery sticking you should be good, but if it buggers up during a flash you'll have a soft brick most likely and as long as you can access recovery you can recover it.

- Create a Nandroid backup (store it on SD on tab and on your PC)

- Download USB-ROM and make sure it's on your SD card (should be able to just download it from the website and it'll be in the sd card in the 'downloads' directory)

- Download the GAPPS file and stick on on your SD card (same as above, should be in downloads)

- Reboot to recovery

- Wipe Cache

- Go into advanced and wipe the dalvik cache

- Go back to top menu and perform a factory data reset

- Wipe cache (just for good measure)

- Wipe the dalvik again (just for good measure)

- Install zip from SDCARD (choose the USB-ROM zip you downloaded)

- Install it, read what it says for any errors, when successful continue..

- Install zip from SDCARD (this time choose the GAPPs you downloaded)

- Install it, when it finishes reboot

viola, you should be done now.

I really don't like working from toolkits, I used the toolkit only to unlock, root and flash custom recovery the first time since it was the simplest way.

From there on out I always work from fastboot or recovery to do any updates.

Ho9984

Before i do any of this, i have to be unlock and rooted first correct?

mzilvar

iTrader: (3)

Yep.

Very first steps should be..

- Enable the dev options & turn on USB Debugging
- Root / Unlock / Load custom recovery
- Make sure your custom recovery sticks

In order to access recovery you..

- Reboot the tablet
- Hold the Volume + button down during boot
- You should see an android with his guts open
- Press Volume - button to scroll the options, then press volume + button to select 'Android Recovery' (might actually be the power button to select the option)

Stock recovery is pretty limited.

I'd recommend TWRP for this specific application since it'll be in the console, and TWRP is touch-based. Normally I use ClockWorkMod recovery (CWM) but you typically need access to the volume buttons to navigate CWM.

You can root/unlock/load recovery from the toolkit I referenced earlier in the thread.

Be certain your recovery sticks, you don't want it reverting back while you're in the process of moving over to USB-ROM in case you need to access recovery again for some reason.

Once you're all done and it's in the car and everything I do the following to get into recovery:

Install a terminal emulator and use the command

'Reboot recovery'

That'll get you into recovery.

the command 'Reboot' will reboot the tablet from a terminal.


Might need to type in 'su' as the first command and grant root rights if prompted in order to use these. I normally do.

Ho9984

Alright, i really appreciate the effort and help. I already have the tablet fully install. So i cant access the recovery using the power and volume button. i only have access to power.

I try using other methods and tool kits (wugfresh) and quickbook to get into recovery, but i just see android guy with a red exclamation point

mzilvar

iTrader: (3)

Not familiar with those.

terminal emulator should work, available for free in the app store

Alternatively ROM Manager will do the trick, I just wouldn't use ROM manager to try to flash recovery or any ROMs.

Just open ROM Manager and there should be an option in there somewhere to reboot to recovery.

ROM Manager is available in the app store.

Should still be able to plug your laptop into your USB cable the way you did the install? One end is accessible right?

This is actually exactly the reason I chopped the top of my bezel near the power and volume buttons so I could use them still in an emergency if I totally borked something to get into fastboot or recovery. Can't see it at all and I just pop the center AC bezel out to gain the access.

mzilvar

iTrader: (3)

Just a word of caution.

Be careful!!

If you can't access recovery and you bork something up pretty good it can be difficult to recover from it.

Or if you're on stock recovery.

It's not impossible, but you can end up with a soft brick, possibly a hard brick (not familiar with all the cases in which you can hard brick a nexus 7) if you mess it up good enough.

netghoster

Great post. Planning to do something similar on my MDX 2005.

oneglory

just picked up an a100 from ebay for $74, it begins!

oneglory

well, took a while but it's done.

the first tablet I got the GPS was a dud. just wouldn't work dunno if it was a hardware issue or software - the antenna was swapped out but just wouldn't work. It was quite the logcat nightmare. Finally gave up and bought another a100 with a cracked digitizer for an astonishing $38.

everything is pretty much done but I'm getting dirty power it seems directly from the fuse box pretty much on any circuit i try. I have 4 car chargers that I can use so I took one apart and used the board inline to clean up the power between the fuse box and tablet. That should keep the juice flowing nice and clean for it.

I extending the power button and used a momentary switch which I mounted in the center console cubby. I also didn't use any audio hook ups other than the phono cable which was also routed through the center console area and plugged directly into the AUX port. The tablet's mic was also extended and is kind of just dangling above the steering column right now, i haven't really thought about where to mount it.

Grimm Reeper

just saw this mod on FB... this is definitely on my todo list.

DAN!!!

Nice work....looks awesome!