[Discussion/Tips] Nexus 7 as Car-Tablet.

[tesna]

so just recently I add an USB-DAC into my setup, making me requires to get OTG stuff enabled. The default kernel on CM12.1 does not support it, flashed oxydo revamped but boot looped . I really need charging via OTG stuff so I installed Autodroid 1.2 on mine, but still OTG charging does not work on default kernel. Flashed oxydo revamped now otg charging + usb audio works! and I'm happy... but sometimes I found out that the PEM does not always make the tablet auto sleep :S, cannot figure out why.

So I tried to flash kangoroo kernel v2, now the tablet always sleep on power loss but the downside... the tablet does not always wakes up :S (50% works fine, 50% ends up dead) I had to push and hold the power button to revive the tablet back to life. Tried to reinstalling few times but same thing happen. So I'm wondering what's everyone else setup like, what did I do wrong?

EDIT: so I tried to flash CM12.1 with all ext4 with oxydo revamped kernel and now seems working fine (autosleep, auto on, usb-dac, etc) except the firm sleep option. The stock kernel of CM12.1 able to use f2fs on /data and /cache partition. I guess this will be my setup for now.... (I really miss media buttons on the navigation bar tho)

 

[SiK TL]

so just recently I add an USB-DAC into my setup, making me requires to get OTG stuff enabled. The default kernel on CM12.1 does not support it, flashed oxydo revamped but boot looped . I really need charging via OTG stuff so I installed Autodroid 1.2 on mine, but still OTG charging does not work on default kernel. Flashed oxydo revamped now otg charging + usb audio works! and I'm happy... but sometimes I found out that the PEM does not always make the tablet auto sleep :S, cannot figure out why.

So I tried to flash kangoroo kernel v2, now the tablet always sleep on power loss but the downside... the tablet does not always wakes up :S (50% works fine, 50% ends up dead) I had to push and hold the power button to revive the tablet back to life. Tried to reinstalling few times but same thing happen. So I'm wondering what's everyone else setup like, what did I do wrong?

EDIT: so I tried to flash CM12.1 with all ext4 with oxydo revamped kernel and now seems working fine (autosleep, auto on, usb-dac, etc) except the firm sleep option. The stock kernel of CM12.1 able to use f2fs on /data and /cache partition. I guess this will be my setup for now.... (I really miss media buttons on the navigation bar tho)

I'm in the same boat with you. I had to ditch PEM. I ended up using Chroma ROM with franco.kernel. What CM12.1 did you use? Also which version of oxydo revamp kernel worked for you? I'm looking to get OTG working correctly on Nexus 7.

 

[tesna]

I'm in the same boat with you. I had to ditch PEM. I ended up using Chroma ROM with franco.kernel. What CM12.1 did you use? Also which version of oxydo revamp kernel worked for you? I'm looking to get OTG working correctly on Nexus 7.

I tried both CM12.1 nightly (latest) and the snapshot version both are working fine with also the latest oxydo kernel. But I found a major drawback for me making me trying out another rom/setup. Everything is running perfectly, including the PEM. Until I had to do a reboot. The audio never routed thru USB-DAC if the tablet is connected with OTG-cable during booting. The tablet needs to be booted with OTG-cable disconnected from the tablet, then if I plug the OTG cable after boot the audio routed thru USB-DAC fine. This is will be difficult for car install, it means I had to disassemble the dash (to unplug the otg cable from the tablet) after each reboot.

On autodroid or usb rom I never ran into this issue. I wonder is there's any settings to enable usb-dac to be hot pluggable? This is the only problem I experience on LP rom

 

[tesna]

Another update, so I tried to go back to Autodroid and things works fine so far for a while, but I noticed something different in the sound output. I am by no means audiophile but I noticed the music playback sounds better when I was running LP, especially when playing flac files. I was thought, am I crazy? Placebo effect? Then I tried to flash usb rom, sounds relatively the same compared to Autodroid.

Out ouf curiosity, I flashed nandroid backup of my CM12.1 install........ and immediately notices the difference. After researching around it seems on LP renders the audio at 96khz, and it's confirmed by looking at the stream0 file in /proc/asound/card2/stream0 file

FiiO DigiHug USB Audio at usb-tegra-ehci.0-1, full speed : USB Audio
Playback:
Status: Running
Interface = 3
Altset = 2
URBs = 2 [ 5 5 ]
Packet Size = 582
Momentary freq = 96000 Hz (0x60.0000)
Interface 3
Altset 1
Format: S16_LE
Channels: 2
Endpoint: 3 OUT (ADAPTIVE)
Rates: 32000, 44100, 48000, 96000
Interface 3
Altset 2
Format: S24_3LE
Channels: 2
Endpoint: 3 OUT (ADAPTIVE)
Rates: 32000, 44100, 48000, 96000

On the same file on KK/JB the rates always at 44100.

Guess I'm going to stick with LP now and hope I will never restart the tablet lol....... Anyone know how to patch the rom for enable usb audio even when the OTG cable is plugged during the boot times on LP? I guess this is enabled on timur's for nexus 2013 so this should be possible on LP....

 

[kiepas96]

Hi i recently installed nexus 7 in my car, but i have a few problems, maye someone can help me

Nexus 7 wifi 2012
twrp 3.0.0.0
Chroma rom 5.1.1
kernel oxydo revamp #3-4.9 which version is newest/stable?
supersu 2.4.6
pem 1.8
tasker profiles
stickmount
usb otg y cable from ebay and one which i made my self (pins 4+5)

- sudden ubs stick unmounts
- random freezes and restarts
- sometimes dont wake up from sleep
- a lot of noises from nexus

 

[SiK TL]

Your problem is going to be PEM. I had to ditch it and used MacroDroid to automate the tablet powering on/off

 

[kiepas96]

Your problem is going to be PEM. I had to ditch it and used MacroDroid to automate the tablet powering on/off

updated to BSZA newest build full wipe, still te same with usb
i will try that macro droid
how do you set up cpu and which app?

what about host mode and charging?

 

[SiK TL]

I'm using Chroma 5.1.1 with franco.kernel. he doesn't condone tweaking the CPU through the kernel. So I just left it alone. On other ROMs I run ElementalX and I use his own app to tweak kernel settings.

 

[kiepas96]

I'm using Chroma 5.1.1 with franco.kernel. he doesn't condone tweaking the CPU through the kernel. So I just left it alone. On other ROMs I run ElementalX and I use his own app to tweak kernel settings.

how about usb host and charging at the same time with franco kernel?


Someone posted a timurs kernel for 2013 nexus
in archives there is a updated PowerManager will try it tommorow

https://turbolec.wordpress.com/

edit: newer version of pem works better for me

is there any chance to lock usb stick when device is going to sleep? anyone solve that problem?

 

[alexandru.j91]

hello guys , i have made a custom center console for my golf mk4 it is a side slider ( I can remove tablet when I want),but i have a problem with the tablet , i need the option to wake up screen when charging . I am using slim rom and it doesn't have this option , on cm12.1 it had this opption ..tx

 

[Comprox]

Hey, not sure if this is the best place to ask, but I need help getting an amp. I have an OTG cable coming out of the tablet and into a DAC converter. Is there a known good amp that I can bridge the gap between the DAC and radio harness that will fit behind the tablet in the console?

Thanks!

 

[fuzzie]

Not sure if this is the place to ask...
I have a Beringer DAC installed
http://www.amazon.com/gp/product/B0023BYDHK
My OTG connection seems to be very finicky.
Sometimes audio and power work.
Sometimes just audio works.
Sometimes power.
I've tried several OTG cables. Thought the port might be bad, so I returned the Nexus 7 and tried a new one.
I've tried a powered-USB hub.
Right now, I'm running ElementalX and CM12, but I have tried stock, and CM10-13. With the same result.
Trying to get Timur's Kernel to install...maybe that will fix it.
Anyone else having that issue?

 

[shantur]

If anyone is interested in Android 6.0 for using in Car I have ported the usb changes from Oxydo kernel to DC-Kernel and use OmniRom-HOMEMAKE. Its working well and it has got Double Tap to Wake as I don't keep the screen on 100% of time. Thanks to @daniel_hk for his good work.

To use it you will need to
1. Install latest OmniRom from the thread and install SuperSU Systemless Root as mentioned in thread.
2. Replace boot image with the one link in fastboot mode : Link to bootimage

fastboot flash boot boot-usb-host-charging.img

3. Follow steps in OP for Oxydo Kernel / Lollipop.

- I use PowerEventMgr-1.8.apk for enabling the hostmode charging and fast charging in host mode and fixed install mode.
- MacroDroid for switching off the tablet if not powered and screen is off after 1 minute of loosing power. In this way my tablet is still charged even when I am not driving for a couple of days. Macros in the bootimage link
- Disabled off-mode-charging to power up tablet when usb is powered up

 

[fr4nk1yn]

I'll be catching up with the thread.
While I'm using a '13 many of the things I've encountered will cross over to the '12. Maybe, the processor is still quite limited.

If anyone is interested in Android 6.0 for using in Car I have ported the usb changes from Oxydo kernel

Will give this a try.

Not sure if this is the place to ask...
I have a Beringer DAC installed
http://www.amazon.com/gp/product/B0023BYDHK
My OTG connection seems to be very finicky.

The problem is USB audio IS very finicky. I often had to reboot just to get it going again.

Hey, not sure if this is the best place to ask, but I need help getting an amp. I have an OTG cable coming out of the tablet and into a DAC converter. Is there a known good amp that I can bridge the gap between the DAC and radio harness that will fit behind the tablet in the console?

There's many on amazon that will do this. Alpines seem to be popular.

Someone posted a timurs kernel for 2013 nexus
in archives there is a updated PowerManager will try it tommorow

https://turbolec.wordpress.com/

edit: newer version of pem works better for me

My experience with Timur's has been quite positive. He's a little short when it comes to bug reporting, but the kernel does better than the alternatives.

 

[virtualspeed]

If anyone is interested in Android 6.0 for using in Car I have ported the usb changes from Oxydo kernel to DC-Kernel and use OmniRom-HOMEMAKE. Its working well and it has got Double Tap to Wake as I don't keep the screen on 100% of time. Thanks to @daniel_hk for his good work.

To use it you will need to
1. Install latest OmniRom from the thread and install SuperSU Systemless Root as mentioned in thread.
2. Replace boot image with the one link in fastboot mode : Link to bootimage

fastboot flash boot boot-usb-host-charging.img

3. Follow steps in OP for Oxydo Kernel / Lollipop.

- I use PowerEventMgr-1.8.apk for enabling the hostmode charging and fast charging in host mode and fixed install mode.
- MacroDroid for switching off the tablet if not powered and screen is off after 1 minute of loosing power. In this way my tablet is still charged even when I am not driving for a couple of days. Macros in the bootimage link
- Disabled off-mode-charging to power up tablet when usb is powered up

Hi,

How do you open PowerEventManager? I installed the app but it's nowhere to open. It doesn't show in app list.
I'm also unable to convert it to system app with TB...

edit: how do you enable usb charging with Y OTG cable?
I flashed the boot image you provided but it doesn't work

thanks

 

[donjamal]

hi guys, i removed the battery from my nexus 7, i put it in the car directly from cig lighter charger. the screen sometimes goes fully black, then other times it goes all white or green and the only solution is to remove the power source, wait a bit and plug it back in. what can cause this? if i plug it into the charger at home, i don't see this happening. i left it on charger during the whole night and in the morning it was still running. i tried it with a power bank and the result is the same, it goes crazy...

 

[ponitsoua]

hi guys, i removed the battery from my nexus 7, i put it in the car directly from cig lighter charger. the screen sometimes goes fully black, then other times it goes all white or green and the only solution is to remove the power source, wait a bit and plug it back in. what can cause this? if i plug it into the charger at home, i don't see this happening. i left it on charger during the whole night and in the morning it was still running. i tried it with a power bank and the result is the same, it goes crazy...

You should use the battery. It helps the tablet work on the corrent voltage range. The car voltage is different and it is depending on the rpm the motor is running something that is not happening with a wall charger maybe that is your problem.

(Also the cigarette lighter on most cars does not have a good chassis ground)

Sent from my GT-I9506 using XDA-Developers mobile app

 

[virtualspeed]

It happens the same to me feeding the tablet directly from the battery with a common 12V to 5V adapter. I bought a DC DC voltage step down converter and will set it to 3.9V (common voltage of fully charged li-on batteries). I also plan adding a big capacitor to the 3.9V side to maintain the current stable. Lets see if this works.


edited

 

[fr4nk1yn]

I'll take a look on Timur's forum and see if there an outside link I can post. That's not an uncommon mod.

Quick idea though is your adapter, try another one.

 

[donjamal]

You should use the battery. It helps the tablet work on the corrent voltage range. The car voltage is different and it is depending on the rpm the motor is running something that is not happening with a wall charger maybe that is your problem.

(Also the cigarette lighter on most cars does not have a good chassis ground)

Sent from my GT-I9506 using XDA-Developers mobile app

yes, but i can't charge it fast enough and it always dies on me. also, it gets freaking hot

---------- Post added at 04:40 PM ---------- Previous post was at 04:39 PM ----------

It happens the same to me feeding the tablet directly from the battery with a common 12V to 5V adapter. I bought a DC DC voltage step down converter and will set it to 3.9V (common voltage of fully charged li-on batteries). I also plan adding a big capacitor to the 3.9V side to maintain the current stable. Lets see if this works.


edited

i'm waiting for my stabilizer to be built by one of my friends but he is taking his time, lol