N810 and USB OTG Cable - my homemade solution.
 

Searching for a small, suitable USB otg cable yielded nothing. So I went about making my own...

This donor cable was bought from a mobile phone store.

http://img207.imageshack.us/img207/2395/dsc00047ok8.jpg

One end is a suitable Micro-AB plug. The other end goes to a 3.5mm EIAJ soclet (Nokia socket.) The cable was intended to charge MicroAB devices like the Razr2. The nice thing about it was the connector wasn't inset into plastic moulding, the case could be "unsnapped" to yield the innards.

I desoldered the MicroAB plug and set it aside.


Initially I had the idea of soldering a TINY MicroSD card reader directly to the plug. However a part of me felt a generic OTG dongle was better. So next I needed a USB-A socket.

http://img207.imageshack.us/img207/4581/dsc00050xd3.jpg

I knew those Microsoft mouse USB->PS2 dongles would come in handy eventually ;)

A few minutes peeling plastic away and I was left with this:

http://img375.imageshack.us/img375/7097/dsc00052uc4.jpg

Donor USB-A socket was removed and set aside. The next step was soldering both MicroAB plug and USB-A socket. ID pin was soldered to ground.

A quick test:
http://img207.imageshack.us/img207/2954/dsc00055hi6.jpg

...and all's well.

Unfortunately the tiny wires like this weren't secure; so next we smother with hot-glue.

http://img179.imageshack.us/img179/1576/dsc00059ri5.jpg

Again - still too much flexing. So I bought out the thermoplastic and shaped it around the dongle.

Final product:
http://img527.imageshack.us/img527/5798/dsc00062ii0.jpg

The dongle switches the N810 to OTG mode without using USB Control. It's a little larger than I hoped - but for V0.01beta it's fundtional! Ideally I'd have liked a MicroAB plug that sits flush in the socket so I can leave the kickstand shut and feed wires to the back.




Now that's fine and dandy for low powered devices like the SD card reader. However I used a USB-A socket so as to try different things. This means I need a power injector.

I ended up buying a Camelion Cellphone Pwer Stick fom Maplin for £4.99 This uses 1 1.5v/1.2v battery and some special electronics to raise the voltage to 5V. Perfect for us!

However the camelion uses 2.5mm Jacks for power connectors. I had no spare 2.5mm plugs, so I decided to butcher one from the new packet!

Splicing apart a FlexUSB connector there was a tiny bit of space available to feed a few extras wires through. I added the 2.5mm jack and the old 3.5mm EIJA socket.

http://img207.imageshack.us/img207/1165/dsc00063pw2.jpg


So I basicaly now have:
1) A small MicroA ->USB-A dongle.
2) A flexible USB power injector that takes a single AA battery.


http://img527.imageshack.us/img527/1647/dsc00066ji1.jpg

Re: N810 and USB OTG Cable - my homemade solution.
 

Cool project. And an excellent write-up.

I like that 90 degree solution; there's nothing like a thumb-drive sticking straight out the end of my N800. :(

Re: N810 and USB OTG Cable - my homemade solution.
 

It's like an online job application to work with jolouis and company. :D

Re: N810 and USB OTG Cable - my homemade solution.
 

yabbas doesn't want to leave [East?] London for Canada :P

(If my IRC memory serves me well...)

Re: N810 and USB OTG Cable - my homemade solution.
 

Hey, work is virtual now! Just recently I've been working with Poland, the Czech Republic, Finland, Canada and Russia... from my house! :D

Re: N810 and USB OTG Cable - my homemade solution.
 

I love receiving and signing for goods via email :P

Re: N810 and USB OTG Cable - my homemade solution.
 

ya lost me.

Re: N810 and USB OTG Cable - my homemade solution.
 

I was thinking that it would be cool to have a USB adapter that wraps around to the back of the device, so that you could plug in flash drives or other USB things and not having them sticking out to the side. A flash drive could just hang out behind the device.
I'm no hacker, so there's no chance of me making such a thing, but maybe by throwing the idea out there, someone else will be inspired to make it real.

Re: N810 and USB OTG Cable - my homemade solution.
 

I've posted on that kinda idea before; I'd like a whole backpack, though, not just an adapter. (Containing mondo battery, USB hub, and maybe some integrated USB peripherals with switches to disconnect when not in use.) Maybe, someday, I'll make one... or several, since there is some interest from others.

Re: N810 and USB OTG Cable - my homemade solution.
 

Is a flush micro A/B connector even possible? That would sure open possibilities.

On a somewhat related note, my current holy grail is a low-profile car cigarrette lighter adapter. Stupid Ford Taurus designers have the console armrest interfering with the space... :mad:

Re: N810 and USB OTG Cable - my homemade solution.
 

Flush connector (Y'mean with a flex sneaking back under the kickstand?); don't think so; but it's rumored that there's USB on the back; if so, a replacement battery door could work wonders.

Re: N810 and USB OTG Cable - my homemade solution.
 

Thanks for the comments peeps :)


I had thought about a wraparound connector, that's how it was originally.


Unfortunately the kickstand covering the port forces people to keep the unit open at all times, having the connector flush on the back makes it awkward to plug things in and out. [I also like to see the flashing bl000 LED on the microsd reader, heh.]


I have an idea in mind. My idea is a thin box that snaps to the back of the N810and is flush with the N810 dimensions. This box contains a high-power lithium ion battery (akin to the N810's), a small charge circuit, a small 5V regulator, USB hub circuitry, USB->SATA convertor, a 2.5" hard drive, and the contents of a small Huwaei E168 modem. External connectors include 2*USB-A, a small charge socket, and a small charging plug... [SATA may be overkill, I may just stick with as many SD Card reader circuits (or just the two, or maybe just a CF card reader) as that may be smaller, lighter, cheaper, better on battery life, better OTG as less damage to moving parts, and quicker!]


This is only an idea mind you, I need to see if OTG supports USB hubs. iirc it doesn't which is the main downer in my plans for world domination :(



Here's another idea, this time scuppered by the simply fact that the MicroAB plug was too large :( ... Micro-AB plug with a Flat Flex Cable running to the back of the N810, secured to the MicroSD card reader [or a tiny SD Card reader to give more memory options]. Hopefully there's enough space between the kickstand and the N810 body to allow for an FFC to run between them. Like I said though - the microAB plug itself sticks out so this won't work. One workaround is to get an FFC with the same pitch as the MicroAB socket, then secure a small bit of foam/polystyrene to the back of the FFC [enough to push it securely against the MicroAB socket] - the remaining FFC running behind the N810 as described before.

If Benson's right about USB on the back, then it opens up a LOT more possibility! Namely, no faffing with kickstands, FFC's and the like!

Re: N810 and USB OTG Cable - my homemade solution.
 

The spec, I think, doesn't require support of hubs; the implementation on the N8x0 does. (It sends an annoying message that it is unsupported, but it works anyway.)

Using flex that way, yeah, it could work... 0.65mm pitch for micro; 0.8 for mini. If such cable could be found, that'd work nicely.

Re: N810 and USB OTG Cable - my homemade solution.
 

What I prefer for things like this is epoxy. I get the moldable epoxy putty, and you can shape it however you like. After it sets up you can use files, sandpaper, or whatever you like to sculpt it further. I've used it on several electronics projects, and it works great for me. It's non-conductive, strong and hard, and it's paintable if you want.

Re: N810 and USB OTG Cable - my homemade solution.
 

I should've just tried it! :) You're right Benson - it complains the hub isn't supported (also complains the microSD reader isn't supported, methinks someone screwed up the error messages since they both work!)


So yeah - it worked and it worked well! I'll take a picture of the frankenstein setup later.

N810->USB-A OTG dongle->hacked FlexUSB Power Injector with Camelion battery->USB 4-port hub==>Huwaei E220 & microSD card reader & another microSD reader.

Huwaei modem (this one is the E220, not E168 I was after) was detected in dmesg [still need to find a way to set it all up though, will do so later] - the modem draws 500mA from the port so wouldn't work direct from the N810 without the injector.

microSD readers both worked as expected in addition to the above, showing 2 "removable drives" in the file-manager. Better yet - even without the power injector, both microSD readers + hub worked well drawing power from the N810 [should be simple enough to basically add an extra 2 microSD cards to the N810 without bulky addons that basically sit flush on the back of the N810!]



As for FFCs, I see a LOT of companies out there that would do an order made to measure. However I doubt very much they'd offer something to an end-user such as myself :( They'd probably want an order in the thousands. I'll keep scouring the likes of RS Electronics, Farnham, Maplins, EPO, etc


Without knowing more about the battery USB connections (you sure they're not JTAGs like on the N800?) I think FFC is the way to go.

Also instead of a custom lithion ion battery + charger + regulator setup, I reckon we could get away with a hacked Camelion battery + custom snap in AA battery connector [something that can accomodate 1 or 2, or maybe more depending on dimensions AA or AAA batteries]. The batteries can be wired in parallel to provide more amperage; and since they're standard you can charge them anywhere.


How much interest do you reckon people would have in a few solutions like this? I need money to fund a PhD *grin*



Some typically needed measurements for FFCs: http://www.imperial-connect.co.uk/pr...c/FFC_info.asp

Re: N810 and USB OTG Cable - my homemade solution.
 

sgosnel: I'll have a ganders at epoxy putty. I've tried the polywhatsisface plastic you melt and mould but it hardens too quickly :( [looks so amateurish at the end of the day.]

Re: N810 and USB OTG Cable - my homemade solution.
 

My info on USB in the battery compartment is from here, and nowhere else. It merits further investigation, IMHO.

(Note Texrat specifies those pins are used for something else shortly below, but if you read on, Igor contradicts him. And Igor knows some serious stuff about hardware... but he didn't say they are USB, either. So it's still rather inconclusive.)

Not anymore, it ain't. Just keep on a-readin', stranger; there's USB in them hills.

Re: N810 and USB OTG Cable - my homemade solution.
 

Hmmm, texrat implied they were used for factory firmware flashing - which would indicate they're JTAGs for the flash chip? I'd have assumed there would be 5 exposed pads (one for ID) if it were USB.

Where are those high-rez pictures of the N810 PCB? We can probably follow the traces back :D


I wonder if a simple continuity test with the USB port is in order?

Re: N810 and USB OTG Cable - my homemade solution.
 

There's heat-shrink tubing and compound, too

Re: N810 and USB OTG Cable - my homemade solution.
 

Hi Guys,
Sorry I'm a bit late getting to the table on this one! Neat little setup btw, like the concept! I've been rather swamped recently with other things, but my mind is still working away on these N8X0 projects in the background ;o)
A few thoughts. First off, while a flexible cable that wraps around under the kickstand sounds cool in theory, it really would be quite impossible both due to the connector size itself, but more importantly the fact that once you plugged it in, if it was flush so that the kickstand would still close... that bad boy is NOT coming back out... which as cool as it would be is definitely not an acceptable way to go for most people! (Ever tried pulling on something that's connected just via a FFC? lol don't!).
As for the Pinouts in the battery compartment, as far as I know nobody's actually got around to confirming things... I've got all the parts to try it out, I'm just in the middle of moving and things right now so I haven't had a chance to. Basically on the N800 there are two sets of pads, one is definately the JTAG, the other is a set of 4 or 5 almost directly beside the USB port... which strangely enough, when you put the device into OTG Host mode, one of those pins goes to 5V+... and when in device mode, it sits at 0, so that's a pretty good indication that they at least have SOMETHING to do with USB... I've got the pogo pins to try it, but the problem I ran into was getting them aligned properly, determining the correct pinouts, and having them stay in place without building some kind of box that was twice the thickness of the N800 itself to attach to the back of it. Now, granted, if you're going for that whole "hard drive and USB hub and battery packs and....etcetc" you're going to end up with more of a "laptop to wrap around the N800/N810", so the size thing might now be an issue; If I can help out in any way let me know!

One other thing worth mentioning... You can now also get "360 degree" USB adapters that will let you plug things in backwards (i.e. a flash drive facing back beneath the tablet instead of straight out). I would love to be able to find one with a mini-port on one end to modify up (how sweet would that be?!?) but I think the chances of that are slim to non-existent right now; however coupled with the OTG adapter it would work, though still a bit bulky. I'll post up a pic of what I mean this evening if anyone's interested (the adapters are a bit pricy though, something like $10-12 I think).

Thanks,
-Rob

Re: N810 and USB OTG Cable - my homemade solution.
 

My tendency would be to hook up an external USB device, make sure the data's flowing, and jab pads with a scope probe... You see data, or you don't... You know, I've got a scope (or two) at home; I'll give it a shot.

One other possibility in the sneak-cables-under-the-kickstand line is to replace the kickstand with a bulged model... Yeah, you get to make it yourself. Isn't modding fun? (I have access to a machine shop; if I had time, I could just go do it. Few are so blessed.)

Re: N810 and USB OTG Cable - my homemade solution.
 

Let us know what outcome you get Benson :) I'd be interested to know if the pads are USB related! Reckon you can machine a new battery cover? ;)

Re: N810 and USB OTG Cable - my homemade solution.
 

That's a lot more of a pain; the latch is annoying. And the qualifier "if I had time" goes double. I might, at some point, though.

Re: N810 and USB OTG Cable - my homemade solution.
 

/me begins holding breath

Re: N810 and USB OTG Cable - my homemade solution.
 

I'll check the USB tonight; I'll post results in the morning, unless he still has a pulse.

Re: N810 and USB OTG Cable - my homemade solution.
 

Could you post a schematic of the hot glue adapter? Thanks in advance.

Re: N810 and USB OTG Cable - my homemade solution.
 

Here's the schematic, unless I am mistaken:
http://www.accesscomms.com.au/reference/USB.htm

Re: N810 and USB OTG Cable - my homemade solution.
 

Wow, that was fast, thanks!

So you have to ground the ID pin?

Re: N810 and USB OTG Cable - my homemade solution.
 

Yes, that's what puts OTG into host mode, without software switching.

Re: N810 and USB OTG Cable - my homemade solution.
 

Thanks again.

Re: N810 and USB OTG Cable - my homemade solution.
 

Well, no more from Texrat, so I guess he expired.

Those pads (on an N800) are USB...
A & B are data (sorry, not sure which was +)
C is ground
D is +5V

Of course, as you can see from the picture I linked, they're laid out differently on the N810:
(But the identification of signals<->pads, or even that this is the same connector, is pure speculation...) I'm betting that's USB, too.

Could Nokia have been designing ahead for peripheral back-plates here? I think not; else there'd be an OTG sense pad, too. I think they just have a fixture you can drop a bare N800 in and provide power and a USB connection for flashing.

Any use of this will probably require software switching or hardware hackery (adding a switch to toggle OTG, and also disconnect the data lines, would permit connection to a PC through the mini B port).

Re: N810 and USB OTG Cable - my homemade solution.
 

So next questions:
...are these pads the same as the connector on the side, or have we got access to a second USB connector now?
...is the +5V restricted to 100mAh like the OTG socket?
...and can we create our own peripheral back plates with spring probes to USB-A?


I don't think software switching would be a problem for users. But having to swap backplates all the time (if you wanted to plug it into a PC) would be irritating.




Peripheral back-plates, here we come! :D

Re: N810 and USB OTG Cable - my homemade solution.
 

They're the same port; if they weren't, there'd have been no data on the pads for me to watch...

I presume the same current limitation applies; it can be disabled with a kernel tweak, provided the backpack also has a battery and power-injector; or just use a powered hub, get more ports and no kernel tweak needed.

Yes, we can make peripheral battery-packs with a power injector or powered hub, a fat-max battery, wired ethernet adapter, USB-RS232, and even SIS-based USB-VGA.

(Or, you could leave some of that out, but I would include everything except maybe the USB-VGA. With switches to disconnect everything, there's no power drain unless you use it...)

Re: N810 and USB OTG Cable - my homemade solution.
 

Well there you go, long time suspicion finally confirmed! Thanks Benson!
I had imagined that the pads were just second points for the original USB connector, as Benson mentioned, since it really doesn't make sense based on the location and device to be brought out otherwise.
Of course how practical all this turns out to be is another question, but with the ingenuity that's kicking around these forums I'm sure there will be some interesting (if only one off and impossible to reproduce) results...

Re: N810 and USB OTG Cable - my homemade solution.
 

Wow, that's awesome! Thanks Benson.

So in that earlier thread, Texrat was telling the truth in the most misleading way possible? :eek:

Re: N810 and USB OTG Cable - my homemade solution.
 

Would he ever do that?

(I think he was actually being completely honest, and correct, but didn't know the whole story...)