Keyboard Docking Station
for the Nokia 770
Internet Tablet

Nokia 770 Docking Station

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3 Feb 2007
If you read the reviews of the Nokia 770 Internet Tablet, you will find that some of them are not too favorable. While the new N800 has gotten somewhat better reviews than the 770 did, a common criticism is the lack of a keyboard. The Nokia Tablets do provide handwriting recognition, and not one, but several on-screen keyboards. These solutions, however range from tedious to nearly unusable. I understand that the Nokia Internet Tablets are designed to be web surfers and media players, and are not intended for heavy text entry, but even entering a URL can be frustrating.

My needs do, however call for some text entry. What I really want is a highly portable, inexpensive device that can do everything the Nokia Tablets do, but also is a laptop replacement. I need access to a UNIX command line for things like ssh, as well as something I can use to produce the content for, like I am doing right now.

Given that the 770 does provide (unsupported) USB host mode, I figured that there should be some way to add a keyboard. After reading some info on Internet Tablet Talk (Link Below),  I was able to wire up a fairly simple solution to add a keyboard to my 770.  It was a solution, but it was rather awkward, and seriously impeded the mobility of the 770.  There had to be a better solution.

The Nokia 770 does not support USB host mode as shipped by Nokia.  Please see disclaimer below and links below.

First Solution
The Nokia 770 does not provide power for peripherals, as USB normally does.  In fact, it actually requires an external source of a regulated 5 volts.  A simple solution was to literally bolt a small USB hub to a USB battery pack.  The USB battery pack provides a regulated 5 volts from 4 AA batteries.  This was wired into the USB hub, and the hub was modified so that the +5 powered not only the downstream (Peripheral) connections, but also the upstream port.  Lastly, the cable on the upstream port was replaced with one that had a mini-USB plug that fits the Nokia.

First Solution was a modified USB HubFirst Solution shown with Logitech PS2 Keyboard
My First Solution used a Battery powered hub to allow standard USB peripherals,
 such as a keyboard, to be used with the Nokia 770.

This arrangement did allow USB keyboards to be used with the Nokia 770, but it required quite a bit of setup each time it was to be used.  The fact that the USB connector is on the bottom of the 770 made it difficult to prop up, even with the "stand" that is included with the 770.  It was also rather bulky.  The USB hub was mounted on top of the battery pack, making it rather a large lump in a backpack or carry case.

Really Making the 770 a Practical Laptop
For use with the above, I purchased an even smaller USB keyboard.  This keyboard is not much larger than the 770 itself.  Holding the 770 above the little USB keyboard suggested a tiny laptop.  Could I really make something that turned the 770 into a sub-subnotebook?

To be practical, It had to meet several requirements:
  1. The keyboard, while small, is wider than the 770.  The completed device could be no wider or deeper than the keyboard.
  2. The completed, folded device should be as close to the thickness of just the keyboard and the 770 as possible.
  3. The 770 must not be physically modified in any way, and much still be quickly usable on it's own.
What I needed to build was basically a dock.  It had to hold the 770 securely, contain the batteries and USB hub as above, but be be small enough to satisfy the size requirements mentioned above.

The basic structure is made from marine polymer (Such as that sold under the tradename StarBoard).  It is strong, relatively light, and easy to machine.  Several features had to be machined into the chassis. Most of it was done using a Dremmel tool with the Dremmel router attachment.  Here is a list of the main features of the polymer chassis:
There is a clear cover over the batteries and electronics that is cut from the top cover of a CD jewel case.  The bottom of the cover is slotted to allow the cable from the keyboard to pass through.  Some extra room must be allowed in both the cover and the cable well so that the cable is not pinched when the unit is closed.

Electronic Components
The Nokia 770 Keyboard Dock's main component is a 4 port USB travel router.  Before it had the misfortune of meeting me, it looked like this:
4 Port Travel Hub before I got to it
I removed the case, the upstream cable, the power jack (not seen), and the top (right most) USB connector.  That first port is going to be for the keyboard.  By using the top one, the remaining 3 ports are available for peripherals, and are lower on the side of the device.  This helps to prevent connected cables and devices from tending to pull the unit over, and leaves room for the stand. (See side view, below).

As I mentioned the 770 does not supply power to the hub.  In fact it needs to be powered by the hub.  This means 2 things:  1) I need a source of 5 volts, and 2) I need to modify the hub to send the power back upstream to the (770) host.  The latter is accomplished by finding the diode, and replacing it with a jumper.  What do I mean by the diode (italics)?  All of these devices have a diode that allows power to flow from the host or an external source of power to the peripherals while preventing power from flowing upstream to the host.  But in our case, we want the power to flow upstream.  Using a DVM, and a magnifying glass it is easy to find the diode.  It is circled in the picture below.

Location of Diode
OK.  Fine.  The hub will now power the keyboard, peripherals plugged into the other 3 USB connectors, and the 770 -- but where does the power come from?  Well, we could use 4 batteries, and regulate it down to 5 volts, but given the size requirements previously mentioned, there simply is not room for even "AAA" batteries - at least not without some weird arrangement.  There's plenty of room for 2 "AA" batteries, though, and fortunately there are lots of things that will efficiently step the 3 volts from 2 "AA" cells up to a regulated 5 volts.  At first, I tried the circuit board out of an iPod Shuffle (original) battery extender.  This device was designed to run the iPod Shuffle from 2 "AAA" batteries:

iPod Suffle1 battery extender disected
Either it did not survive my dissection, or it will not work without talking to the iPod.  I gave up and tried something else:

Cellphone charger
This device is intended to charge mini USB cellphones from 2 "AA" batteries.  If it is for phones that charge via USB, it must put out 5 volts right?  Well sort of.  Since it is intended as a battery charger, it attempts to do some sort of current detection.  This causes some problems, but it mostly works.  (See the Usability and Issues section.)  The circuit board is tiny, and can be seen just under the batteries in the pictures of the completed device. 2 wires carry the 5 volts to the USB hub.
Note of Trivia: guess what the USB hub does with the 5 volts we send it? It regulates it down to 3.3 volts! Don't worry, our effort was not in vien. We need the 5 volts for the 770 and for our USB peripherals.
With the hub powered, all we need to do is wire it to the 770.  Totally by accident, it was my original Nokia USB cable that gave its life for this part of the project, as did a Belkin car charger for Nokia N series phones.  Most of the molding is carefully cut away from the plugs, and the remaining cable is cut to length.   The connectors are glued into the bottom of the dock, using the 770 itself to get them positioned just right.  The 770 was protected with some waxpaper.  I just used hot glue, but I would really recommend epoxy. 

Connections at bottom of docking area

The power connector is simply wired to the left size were I put a standard coaxial power jack (not shown here).  The power jack was the one removed from the USB hub circuit board. It seemed almost exactly the same size as the larger, older Nokia charger jacks.  Standard Nokia chagers seemed to fit fine, until I tried a 3rd party Nokia charger.  It seems to have broken the connector, so I will replace it the next time I find a dead Nokia cellphone.  I wanted the older, larger Nokia connector since I have lots of those chargers laying about.  Another cool idea would be to use the insides of a Nokia compatible USB charger cable.  That, wired to the power connector, and a female mini USB connector on the side, would make your 770 chargable from USB.  Readily available chargers for Motorola cellphones (Such as RAZR and MING series), as well as BlackBerry would work too.

Nokia phones seem to complain if a power connector is inserted, and then no power is applied.  The 770 seems not to.

I did not include an audio connector at this time.  The 770 detects an audio cable being connected and changes certain audio settings.  This could certainally be overridden in software, but Nokia is still not particulary forthcomming about the innards of thier low-level audio drivers.  Certainally the info is out there, but I opted to just skip audio for now.  Headsets or Headphones cannot be used when the 770 is in this dock.

Lastly, the keyboard is dissasembled, and the wire is made to exit from the top as seen at the right side of the above picture.  It was cut short, and hard wired into port 1 of the USB hub.  Note how the cable exits parrallel to the hinge line.  This allows the cable to twist, rather than bend, as the unit is opened and closed.  It also prevents the stress on the cable from being concentrated in any one small spot.  The cable actually pushes up a bit toward the hub when the unit is closed.

Finishing Touches
A few things are added for finishing touches.  The following photo shows the hinges. A little glue adds strength, especially on the keyboard side.  Also shown is the stand, and a small magnet near the center to keep it closed.  Yes, the stand really is made from a coat hanger.

Back view

Another magnet, and a screw inserted into the keyboard is used to keep the whole thing latched closed.
A cover for the batteries and the electronics is cut from the cover of a CD jewel case. (hard to see since it is clear).

Here's a side view showing the stand, and the USB connectors.
Side view
I was going to paint the device black.  It would look a lot more professional.  I have not done this yet for 2 reasons.  1)  I would have to take the whole thing apart again, and 2) Many paints will not stick to StarBoard.  It is a little like trying to paint butter.

USB Host mode
To make anything like this work, the 770 has to be put into USB host mode.  This can be done using the flasher program.  See for example, this thread on Internet Tablet Talk.  Once in host mode, the 770 can be put back into peripheral mode temporarily with a command issued as root.  It can then be removed from the Keyboard Dock and used as a card reader just like it worked originally.  A small script can be written to make this easier.

Installing the Bluetooth Keyboard Stuff
Once in host mode, the arrangement described here works, but not very well.  The 770 is designed as a tablet, and most keyboard support has been removed from the OS.  Problems include keybounce, and keyboard working in some apps, and not others.  Fortunately, a package for Bluetooth keyboards can be installed, and this fixes nearly all the problems of keyboard support.  Get the package here.  A big thanks to the folks that worked on this at  You made my project work.

Usability and Issues
This is very definitely a prototype, and as such it has some issues.  The bottom line is that it is actually very usable, and in my opinion makes the 770 a much more compelling device.  The issues below are listed in order of significance:
A few good points:
Possible Enhancements
Given that the keyboard is larger than the 770, we have room for more electronics next to the 770.  Even with my limited manufacturing resources, I could have fit more in that space.  Here's some of the ideas I had:
Future Plans
I may pursue some or all of the possible following options
I'll finish off with a couple more shots.   I really wanted to include a screen shot of a 300G or so partition showing in the 770's Filemanager.  I have a USB Harddrive case, but at the moment no drive to put in it.

Left Side
Connected to Mobile Phone
The left side, showing
the charger connection.
Connected to My Motorola A780
Mobile Phone.  The phone's filesystem
is displayed in the 770's Filemanager, and the Keyboard
Dock is actually charging the phone.

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