Completely Internal OTG Mod *Coming Soon*

[xboxexpert]

www.youtube.com/watch?v=EAnY8tRxGSg

Coming Internally Soon to a Nexus 7 near you...

This is the picture of the device EXTERNALLY;

What we are now trying to accomplish is internally setting this up. I ordered a microSD reb mount connector that will allow a ground to be present once the memory card is inserted. This will allow me to utilize the points for SWITCH and enable disable OTG mode. I also ordered a 5v step-up board to test another theory I would like to put in place, in short, not utilizing OTG mode at all.

 

[zakafx]

haha, as if. i was just saying this to a friend today it would be better to do this instead of using a cable. good job.

 

[xboxexpert]

haha, as if. i was just saying this to a friend today it would be better to do this instead of using a cable. good job.

I'm going to try my best if not make it internal have a CNC MFG'ed USB Dock by next week.

 

[3vo kid]

Very cool! Looking forward to see how this comes out

Sent from my Black "Destroy Mode" Nexus 7

 

[kkl0wn]

Finally somebody that's diving into the deep end on this project. I like it. Keep it up.

Sent from my Nexus 7 using XDA Premium App

 

[the0bserver]

If this can be installed internally, this would prove to be a great solution to the OTG issue... Looking forward to watching progress :good:

 

[khaytsus]

I assume you're aware that previous internal OTG's have interrupted USB communications, have you resolved that part (I assume being able to switch the OTG part in/out as necessary)?

 

[Element515]

Oh, interesting... Get this done, or even a real nice compact USB dongle and I'll get a n7 and buy it from you!


Sent from my iPad using Tapatalk HD

 

[xboxexpert]

I assume you're aware that previous internal OTG's have interrupted USB communications, have you resolved that part (I assume being able to switch the OTG part in/out as necessary)?

Yes I am aware that this is a huge issue for anything data related. I also noticed that most diagrams for D+ and D- are backwards which might stop some progress, which it did in my case. See attached image for CORRECT wiring of a USB Port. I blew out at least 3 microSD Cards already but thats not a big deal to me. However the mouse and keyboard on a hub has been working flawlessly no matter how many times i switch back and forth. Seems like anything that needs to read FAT32 or NTFS is a big fail for me at this point. I think that is more a software problem then anything though.

I'd also like to add to others trying to complete something like this once the Sense switch is grounded 5V is provided out to the device to power it. If the sense switch isn't grounded then 5V is not being pushed only pulled to charge.

 

[littleguy77]

I wish you the very best of luck, as I have been researching this avidly for awhile and sketching out possible solutions in my head.

I hope you and other readers have seen the numerous similar threads on this topic. As I think you are aware, the chief problem relates to retaining the charging/peripheral functionality of the nexus while also permitting it to act as host to mice/drives/etc. Your microswitch is a simple and clean solution for this, although as you mention on youtube you can't do both at the same time. I guess that would be the holy grail. I'm afraid some of the hackers out there are in for a nasty surprise when they complete their mods and realize they can no longer charge their nexus. Your microswitch eliminates that nasty surprise.

For the benefit of readers, here are some similar mod attempts that I've found most informative:
http://forum.xda-developers.com/showthread.php?t=1866988
http://forum.xda-developers.com/showthread.php?t=1854904
http://rootzwiki.com/topic/30797-op...in-micro-sd-card-reader-to-nexus-7-build-log/

Edit: Sorry xboxexpert, looks like we posted at the same time. Glad to see we're on the same page.

 

[xboxexpert]

I wish you the very best of luck, as I have been researching this avidly for awhile and sketching out possible solutions in my head.

I hope you and other readers have seen the numerous similar threads on this topic. As I think you are aware, the chief problem relates to retaining the charging/peripheral functionality of the nexus while also permitting it to act as host to mice/drives/etc. Your microswitch is a simple and clean solution for this, although as you mention on youtube you can't do both at the same time. I guess that would be the holy grail. I'm afraid some of the hackers out there are in for a nasty surprise when they complete their mods and realize they can no longer charge their nexus. Your microswitch eliminates that nasty surprise.

For the benefit of readers, here are some similar mod attempts that I've found most informative:
http://forum.xda-developers.com/showthread.php?t=1866988
http://forum.xda-developers.com/showthread.php?t=1854904
http://rootzwiki.com/topic/30797-op...in-micro-sd-card-reader-to-nexus-7-build-log/

Retaining the charging isn't going to work with OTG mode on considering the 5V is pushed out in OTG mode not pulled in. Its like a break light in a car, reversed polarities + & - when you hit the break when you have your parking headlights on. I don't know of a way at this time because of hardware limitations to make charging work while in OTG mode. Meaning to power the device and have a MicroSD card work all the time is not going to happen in my mind right now. I could try charging while my wiring is plugged in but I'm pretty certain I'll blow at least one thing out on the nexus board.

P.S - 30 AWG Kynar wire (wrapping wire) is the way to wire anything in this tight device not Cat5 wire.... :/

 

[littleguy77]

xboxexpert - Yes, we're in complete agreement. Simultaneous charging and hosting may be the mythical unicorn here, and I'm glad you (unlike some modders) recognize that before pulling out the dremel tool .

The best lead I have on the simultaneous thing would be to implement what the USB spec calls "Accessory Charger Adapter". See Chapter 6, and in particular Figure 6-2 from the specification:
www(dot)usb(dot)org/developers/devclass_docs/BCv1.2_070312.zip

Two problems with ACA, however. I can't for the life of me find a vendor who sells one of these dongles (although there seem to be a few IC's now incorporating the spec). Second I think you would need to physically break the data traces leading to the original micro-b receptacle (the easiest place might be on the ribbon cable). Otherwise you would have data collisions between the internal device and any pc/peripheral/otg device attached to the micro-b receptacle. To permit pc/peripherals/ or other data devices to mate with the nexus, you'd have to install a second micro-ab receptacle into the nexus housing. At the end of the day, the original usb port could be used for charging only, while the new micro-ab port could be used to automagically connect to both peripherals (mice, thumbdrives, etc via otg cable) and hosts (PCs).

 

[xboxexpert]

xboxexpert - Yes, we're in complete agreement. Simultaneous charging and hosting may be the mythical unicorn here, and I'm glad you (unlike some modders) recognize that before pulling out the dremel tool .

The best lead I have on the simultaneous thing would be to implement what the USB spec calls "Accessory Charger Adapter". See Chapter 6, and in particular Figure 6-2 from the specification:
www(dot)usb(dot)org/developers/devclass_docs/BCv1.2_070312.zip

Two problems with ACA, however. I can't for the life of me find a vendor who sells one of these dongles (although there seem to be a few IC's now incorporating the spec). Second I think you would need to physically break the data traces leading to the original micro-b receptacle (the easiest place might be on the ribbon cable). Otherwise you would have data collisions between the internal device and any pc/peripheral/otg device attached to the micro-b receptacle. To permit pc/peripherals/ or other data devices to mate with the nexus, you'd have to install a second micro-ab receptacle into the nexus housing. At the end of the day, the original usb port could be used for charging only, while the new micro-ab port could be used to automagically connect to both peripherals (mice, thumbdrives, etc via otg cable) and hosts (PCs).

In theory if you were to in fact break the trace and split the 5v line to do either or since the only difference is 5v polarity is pretty easy in its self. Fitting it all in the unit with a device that does just that for a all in one effect is quite the contrary. I am however actively building a dock (mock-up) to do just this. So as this thread stated completely internal for what we are trying to acquire, speaking about now, it may be imposable.

Then again if KERNEL Devs were able to detect when the power cable was inserted somehow and switch off or program a feature to defeat this...we would probably be talking a different story. I recall the Nook Color had OTG capabilities that were kernel unlocked down the road. I wonder if I took a stroll over there and did some digging looking into its development if there might be some light shed on this issue. Also if its not a problem now for the Nook Color what was fixed...

 

[littleguy77]

Rock on with the dock. I'll keep my eyes open for that thread I'm looking to build a gaming-oriented enclosure for my nexus, and if an external ACA solution can be found, I'll likely integrate that into my enclosure along with the joysticks, buttons, etc.

I too recall some progress with the nook color. IIRC the nook wasn't actually powering peripherals when in host mode, so the charging thing was a slightly different animal. I may be wrong on that.

 

[xboxexpert]

I am going to remove the Sense wire to trip 5v through the port and instead test with external 5v power to the device. I wonder if the device powered externally will show in Stick Mount. If so I will tear this puppy apart tonight and pin out the entire board to find a solid 5v point. In theory I can as of now pin it to the red wire on the battery giving off 3.9v-4.0v but that would under power a hub but may power a sd card.

More progress tonight let me get back to work

Anyone interested in doing some reading about USB Host Support for Nook Color??

http://forum.xda-developers.com/showthread.php?t=1459892

 

[littleguy77]

There are a bunch of folks looking hard for a +5V pin other than from usb. It's actually not easy since the board is mostly 3.3V and batteries are in series at 7.4v. Before spending a lot of time on this, I would strongly urge you read the links in my post above (post #10). Especially the second link starting at post 14. Might save yourself a lot of headache. Hope this helps.

 

[xboxexpert]

There are a bunch of folks looking hard for a +5V pin other than from usb. It's actually not easy since the board is mostly 3.3V and batteries are in series at 7.4v. Before spending a lot of time on this, I would strongly urge you read the links in my post above (post #10). Especially the second link starting at post 14. Might save yourself a lot of headache. Hope this helps.

Yes we need to find the 5v regulator that regulates the 5v that comes out of the USB port once Sense is triggered. Its somewhere close just need to cut the trace and trigger it for a 5v point.

Also Google LM2940CSX or LM2940CSX-5 is what we would need to down-step the 7.4v line a better option for what we want to achieve. Also looks like that regulator may be the PERFECT fit in where the back camera would go and perhaps solder it to the area for heat reduction.

http://www.mouser.com/ProductDetail...Tw7kGbQ9TGCJPy01/W7fOCrYLg5Oxaj4RaijGJwdWejt/

Looks like I may have a few of those available. I'll see what I can do tonight.

=)

 

[xboxexpert]

REQ ENTERED FOR 2003106-5PCS FOR DELIVERY

I requested (5) of those 5v regulators to test tonight from my stockroom. I'll have some solid progress a lot later on tonight.

 

[nst6563]

There are a bunch of folks looking hard for a +5V pin other than from usb. It's actually not easy since the board is mostly 3.3V and batteries are in series at 7.4v. Before spending a lot of time on this, I would strongly urge you read the links in my post above (post #10). Especially the second link starting at post 14. Might save yourself a lot of headache. Hope this helps.

where do you get 7.4v from when the leads from the battery are reading 3.7 and 1.7?


-unless you're adding the two 3.7v leads together to get 7.4v. In which case you'd need to sum the two leads before the 5v regulator drops the voltage to 5v. Unless that regulator can step up the voltage from 3.7 to 5v (haven't looked up the part #s yet)

 

[littleguy77]

where do you get 7.4v from when the leads from the battery are reading 3.7 and 1.7?)

...and batteries are in series at 7.4v.

Two cells, 3.7V each, in series. (sorry was unclear) At least that's what they're saying in the other threads I referenced earlier. I can't confirm or deny, just passing along info...