Saturday Night USB Host Frenzy : the Full Monty Report
 

Whew. This morning the USB adapters and gender changers I had ordered finally arrived, so I was all set to try out one of the various solutions I've been reading about here for weeks, and hook up my keyboard, hub, and various other things to my 770... yay :-)

(Side note for conspiracy theorists : four plug shapes and two genders... can you believe the USB standard was NOT designed by and for cable manufacturers ? :-)

Below is the account of much hacking, sawing, drilling, soldering, swearing and whatnot.

Warning : if you've read ALL the relevant threads in the forum, you won't learn much, if anything, in this one. All the ideas implemented have been described by others (and credited, I hope correctly) ; there are only minor variations (depending on what was scavenged, what had what plugs etc.). The main point is to confirm those solutions work, add a few pix to the gallery, and, well, rightful bragging after a day's work :-)

The Full Monty (aka the "thoughtfix contraption")

I first set out to build the "solderless" solution first described by thoughtfix, because, well, it's the easiest and most reassuring of all as it doesn't entail any modding of anything.

I had a basic, powered USB2 hub. Instead of the wall-wart I powered it with the battery pack that came with my iRiver H340 mp3 jukebox. I had never used it and all but forgotten it, but by a minor miracle its plug is exactly the right model for the power socket on the hub, so there really was nothing to hack (heh, take that, USB ! :-), just put 4 AA rechargeables in it.

The "Y cable" was in this morning's parcel. It is thankfully short and has a female A plug and two males. One male goes to the 770's host port through a female-A-to-male-mini4pins gender changer. This one is fun, it's two plugs linked by a swivel that twists every which way. It was also the cheapest available, but maybe not the most durable... The other male A fetches power from a hub port for the 770's. The female A goes to the hub's host port, which is a female B - this means there is yet another male-A-male-B cable in between.

What can I say ? It works, first try. I hooked up the keyboard and typed. I plugged in a USB key, it was recognized as /dev/sda1, and mounted it. Very anticlimactic :-)

I did have the 770 reboot on me at one point, as others have mentioned. Those AA cells are probably a bit old, and that USB hub is lit up like a Christmas tree (6 LEDs ! :-). As you can see in the pix below, it's a wee bit cable-heavy and spread out, and the battery pack is big. OK for home use I guess, but probably not something you'd set up in the train or at the local coffee shop :-)

http://www.internettablettalk.com/ga...oto/64/cat/504
http://www.internettablettalk.com/ga...oto/65/cat/504

The Savage Salvaging (aka the "bigboote" device)

At this point, while digging around the entire house for various things, I found two interesting tidbits :

- a broken radio-controlled car in my son's room. It was powered by a 4.8V pack of 4 cells, less powerful but much lighter and smaller than the battery pack, and by another small miracle it still had its charger ;

- a compact hub for laptops -- actually a USB1.1 trinket with a contractor's logo on it, but small, light and transparent. I saw that although it was unpowered the PCB had room for a power socket, just like bigboote's.

So I read up on bigboote's post and soldered two wires in places that would bring power both to the hub's and to the host's ports, unlike a normal hub. Then I had to hack a plug for connecting those wires to the power pack (from an ATX molex plug).

In this mode the Y cable is gone, and the hub has a male A on the host side, so it connects directly to the gender changer on the 770, making for a much less encumbered situation. In my view this an acceptable mobile setup, at the cost of reduced autonomy (but the power pack can be improved uopn easily). It is no less powerful though : just to get even with the ipodders I connected my iRiver H340 to the hub, it was detected and mounted without a hitch, and sudddenly I had 40 GB of disk space on the 770 (at USB1.1 speeds, but hey :-)

Note: spurious reboot here also when carelessly uplugging USB from 770...

http://www.internettablettalk.com/ga...oto/66/cat/503
http://www.internettablettalk.com/ga...oto/67/cat/504

With H340:
http://www.internettablettalk.com/ga...oto/68/cat/503

"I just want my keyboard" (aka the "lbattraw simplification")

Like lbattraw and others, I also wanted to be able to use just my keyboard without all the extra fluff, if necessary.

So with some trepidation I unscrewed and pried open my brand new Keysonic nano-keyboard (have I mentioned that it's cute too ? :-). Damn, but these things have become incredibly simple and empty since the last time I took one apart !

With my trusty Dremel I opened a small path on the side for another couple of wires and soldered these directly at the end of the keyboard's USB power wires. Through another homemade plug I can attach the same power pack as above to the keyboard, powering it and the 770's USB port at the same time ; now there is only the keyboard's cable, plugging directly into the gender changer on the 770. Autonomy TBD, but probably less power hungry than a BT device...

No reboot on plugging/unplugging this one, maybe I got lucky (or cautious :-)

http://www.internettablettalk.com/ga...oto/69/cat/504
http://www.internettablettalk.com/ga...oto/70/cat/504

Live via 770:

Congratulations and thanks for the tech pr0n.

But I'm beginning to think having to go through all these contortions is nuts.

OQO is exertering its pull on me again.

This concludes another episode of the ongoing USB host saga on the 770 :-)

With the accumulated wisdom of previous pioneers and very modest skills, I was able to get all three solutions working in an extended afternoon's work, which should be encouraging for anyone waiting to try it out...

Now I have joined the growing ranks of those impatiently awaiting the software hack that will let us use our keyboards without having the screen blank out every few words : Nokia, anyone, puh-leeze :-)

If anyone has read this far down, I do have a question : I was hoping that a change of languages in the virtual layout would change the real one's layout, but it didn't happen. So how can I get back my French key mappings ?...

Just for fun, one more photo that has nothing to do with the rest :
http://www.internettablettalk.com/ga...oto=71&cat=504

Neato!
Glad my little accidental discovery worked for someone.

I don't understand why your guys USB keyboards work fine and I have the stupid repeat key press problem on mine. I need to try a different keyboard in it I think.

And why mess around with these gothic cabling schemes, when there are a number of BlueTooth keyboards that work well? :)

- Dennis Brothers

Because we already all own USB keyboards. :)

Plus you can mount USB storage devices! I'm going the BT keyboard route myself but if I want some external storage, well, it seems the powered USB hack is the only way to do so at this time.

I myself like the challenge of actually doing something. Who cares if it isn't practical. I learn things and have fun. Better than sitting on your arse all day watching 'reality' television :)

Tonight I modded my little usb box. I removed the switch given that the USB cable should be powered all the time. In it's place I put in a red LED connected to a small circuit I found on the net which causes the LED to flash when the battery gets flat. Since NiMH batteries have such a high self discharge rate I can keep it fully charged by leaving it plugged in at home all the time when I am not on the move. I also added a longer usb cable. My original was too short and rigid. Still have this key repeating problem though.

What about a reality show showing people hacking USB cables in real-time to have KB work with their tablets, charge their nanos... ;)

That might work if they use sexy, geek girls :)

Thougthfix described in his blog dated January 7, http://thoughtfix.blogspot.com/ a schema using Y-shaped USB data cable http://www.xpcgear.com/usbtype2atob.html. Could a USB travel charger provide the +5 V to both USB-keyboard and 770 USB connector via that cable?
The company hama has a power supply providing 5.4 V DC 200mA into a USB Type A socket . It "charges all MP3-USB sticks with permanently installed battery and is also suitable for other USB devices with power consumption up to 500 mA". It is multivoltage 100-240 V AC. I have seen it in a local department store at 16 euros.
Part number is hama 00014056, see techical details: http://www.hama.co.uk/portal/article...67/action*2563.

Well, I focused on the hardware side of things and didn't dwell on that, but I do have the occasional hiccup where a keystroke will be repeated twice or more, if that's what you mean.
When working as root on the command line in xterm, you definitely need to pay attention before hitting the enter key. Makes life exciting :-)

Live via 770 tap-tap:

You the same DB that hung out on Shapiro's Mac CIS forum?

1 - cost, of course.
2 - localization : non-QWERTY BT keyboards are scarce, with USB keyboards (even very specific ones like the Keysonic) I get to keep my national layout.
3 - choice (of form, size, and color :-).
4 - battery life.
5 - sheer fun...

Long ago, in a galaxy far, far away... :)

- Dennis Brothers

Addendum :

While replying in this thread I belatedly realized that in the original post I forgot to credit one very important contributer : CrossBow.

While I did not reproduce exactly his own hack(s), his detailed explanations were decisive and convinced me of the dangers of working "blind" (ie without appropriate instruments) and placing too much faith in the specs of batteries, rechargeables et al.

I followed his good advice and bought a basic multimeter, and have been having so much fun with it since that I now wonder how I've survived so long without it in my toolbox :-)
I certainly couldn't have done all those hacks on the same Saturday without it and without melting something or other... so thanks CrossBow !


PS: a case in point to underscore the sense in his cautious approach of these things, which sounds like paranoia but isn't...
While learning to use my new tool I tested everything within reach that looked like it might carry an electron... like verifying that 4 new AA batteries deliver well over 6V, and 4 freshly charged AA cells well over 5V, etc.
Also, I came across an older made-in-china (are there any others ?) wall wart, the sort with a slider to select voltage between 3 and 9V, another to select polarity, and almost every power plug form factor out there. It was in my son's room, where I used it to power his various toys and gadgets when their batteries ran out. Thus it's had a rough life over the years, but although it had a battered look, it seemed to be still working (in that it powered things).
Looking to test its accuracy at the various settings, I was shocked to find that no matter what the buttons were supposed to select, it now always unflinching delivered between 18 and 20V...
Now I know why those fixed-track racing cars were hard to control in the bends :-)

Live via 770 tap-tap:

Kneel, you peasants!! We have been visited by an UberUberHackerGeekLeet!! I get first touch of the hem of his garment!

Those things are usually quite bad with their voltages at the best of times but yeah, that one sounds buggered!

Also be aware if you're using a digital meter it puts almost no load on the power supply. If you really want to know what the voltage is you need to measure across the supply while it is powering whatever it is.

I was playing with my little powered USB setup yesterday and showing my friends my USB pen drive working. Unfortunately my low voltage warning LED started flashing after only a few minutes. I am sure the drive doesn't use that much power so I am going to try actually measuring the current drains of that and the keyboard I have (which I still can't get to work properly - Grrrrrrr!). I'll wire up a little USB extension lead made from the hacked up Nokia one so I can hook up my meter and measure the current. I will also check the current at the battery if I can. It could be the batteries weren't fully charged. I think the plug on my charger wall wart might be a bit touchy. I need another LED to show when it is charging I guess. Hmmm, actually a dual colour one might be nice.

Gothic cable designs...
 

For those interested, I've removed the "stock" cable on my USB keyboard and replaced it with a thinner, shorter A->mini B cable that has a home-made "Y" at the end. No adapters needed to work on a PC/hub or direct to the 770. I added a 100 ohm resistor in series with the keyboard power which will prevent potentially large amounts of current from flowing if I inadvertently leave the batteries connected when plugging into a hub or PC (and the batteries are discharged). This way it's impossible for more than 50 mA to flow if there's a dead short at the keyboard end, not that that would ever happen ;)

See here: http://lbattraw.home.insightbb.com/