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Nexus 7 (2013, Gen2, FLO) - internal micro SD mod

With games getting bigger and bigger with every new release and limited storage capacity some of you might think the same:
Why not add a SD card to my Nexus 7?
The lates Lollipop update basically killed the normal USB OTG funstions, so if you do want to use a USB stick or external SD card in a reader you will need a powered USB OTG cable.
I am not sure if this was intentionally or another bug but it is damn annoying.
After openeing my tablet to check m options I realised my main problem is space.
Even adding a micro SD with a similar small reader is a major pain as there simply is no empty space left inside.
So I was hoping someone here might be interested in such a mod and contribute with good ideas during the build and maybe even copy the mod (if I manage it) to confirm it is in fact doable.

My findings so far:
A custom rom is a must have due to the OTG limits of the original.
It might be enough to just find a suitable kernel but so far I settled for the Team UB Lollipop release.
It offers some mods based on Cyanogen and claims full OTG support.
Other roms also added support for external WiFi and TV dongles, so there is room to play.
As said space is a problem I am working on ;)
For an internal mod and due to the lack of physical support on the mainboard the only option is to use the standrad USB port for this mod.
This means SD, reader and OTG mod must fit inside somehow.
It also means some sort of physical switch is required for the times when you need full power during the recharge - although I have to test if this still works with an external SD while the tablet is switched off.
In that case I could accept 500mA charge during normal use and 1A or more when the tablet is switched off.
The rom should support fast USB charge but I am not sure if this olaso works in host mode.

It is possible to use some extra app and scripts to make good use of such a mod.
Not only can you use the SD for music, movies and other demanding files but with scripting you can also move the big data files from games to the external storage.
Works similar to the apps you can get for devices with a real SD card, where you often find the "Move to SD" option in the app manager.

This mod will not be for the faint hearted as it requires serious soldering skills on these tiny components, so if you only know how to solder copper pipes you might need some training on old electronics first ;)

Let me know what you think and if you would be interested in such a mod as otherwise I won't bother taking pics during the progress.
And without pics there will be no Instructable follwing ;)

Downunder35m (author) 2 years ago

I have done some more tests and the short story is: it does not work - at least not completely.
Using the USB port for an internal SD failed in my test for the following reasons:

a) While device is in OTG Host mode you can not connect to the PC, I tried with a Bridge Cable but nothing.

b) Charging is pretty limited unless the kernel is custom and provides OTG Host Charge and USB Fast Charge.

c) Adding a switch to disable OTG is not enough as the connected SD will interfere with the data connection to the PC.

In my tests I was only able to see the Nexus popping up in the device manager once for about 2 seconds.

d) If you ignore all the above problems, use Airdroid to transfer files and a QI charging pad you can be a happy camper.

But I don't like the idea as it makes firmware updates a hassle, not to mention PC through ADB.

Although the Team UB Rom offers OTA updates I still think a reliable connection to the PC is necessary quite often.

Conclusion so far:

The mod is possible if you accept a lot of limitations.

Unless someone has a great idea on how to solve the problem I will sign off from the project for now.