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I've been avidly following this thread and several others over at XDA that are trying to accomplish the same thing. While Snow02's post may come across as a little impatient, he (like me) seems concerned about people spending a long time working towards what is already known to be a dead end. He is spot on in his analysis.

After researching numerous threads and the official USB specifications, here are the conclusions I've drawn.

- If you permanently solder the reader into D+,D-,GND, and ID pins, then it still doesn't matter where you get the +5V from or whether the reader is mounted or not. The device won't charge. This is because shorting the ID pin to ground forces the Nexus into host mode, at which point the stock kernel disables charging. Even if the +5v comes externally, it still won't charge. I (and many others on these forums) have verified this directly through testing (see first attachment). Conclusion: you need a way to manually toggle the short between ID and ground, otherwise your device will stay in host mode all the time and never charge. (A kernel mod *might* also solve the problem, but I'm not a kernel dev so I can't speak definitively.)

- If you provide a switch to toggle the ID pin, you still won't be able to connect the stock charger (or any high-speed charger) and use your internal reader at the same time. That's because these chargers short the data lines together, rendering the card reader uncommunicative while charging. Unlike the last item, this is purely an electrical issue that cannot be solved through software. Some people may be ok without simultaneous charger/reader, while for others it's a show-stopper.

- If you permanently solder the data lines from the reader to the nexus, you will have problems if you ever plug the nexus into a PC. Regardless of whether the id pin is shorted or not, you now have two devices - the PC and the reader - tied to the same data lines. Conclusion: if you want to retain the ability to connect PCs or OTG cables to the Nexus's external receptacle, you will need a way to manually switch the data lines between the internal and the external device.

I encourage everyone to look at the following threads, if you haven't seen them already:
http://forum.xda-dev...d.php?t=1884163
http://forum.xda-dev...d.php?t=1866988
http://forum.xda-dev...d.php?t=1854904
 

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Roms like ParanoidAndroid have native support for OTG drives while the stock based roms require stickmount or other similar software. Maybe it's more than just a kernel hack to enable functions - who knows. Looooong way to go.
I may be wrong, but I think effectively all they're doing is baking the stickmount app into the kernel.
 
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