Hacking an old Palm Keyboard.

[camerin]

So the lab tech here was throwing away an old palm device, with the device there was an old palm keyboard. it folds up into a nice small package and it is reasonable to type one. I think it would make a great keyboard for many different uses (blue tooth to phone, usb to laptop, etc) I tore it down and searched the web for info on the device. I found this in a PDF someone made. Determined that my device is the keyboard for a handspring visor (page 7). It does indeed work, and outputs a UART signal at 9600 Baud (set up my bus pirate to verify).

Now i am kind of stuck. Should I

A: Program a micro-controller or FPGA to interpret the serial data and push it to a useful medium.
Makes the device bigger by adding another circuit
Mean i have to record every key press and release and interpret them as they come
B: Program a micro-controller or FPGA to interpret raw data from the lines, and push it to a useful medium.
May be more work than it is worth
May destroy the device (liberating the glue from the current board.
C: Cobble together a UART to USB adapter and write drivers for the keyboard interface
Makes it big
I have no experience i driver writing
D: scrap the project i am in over my head, and it is cheaper to buy a small keyboard
Don't want to, i love the keyboard but some times you got to cut your losses

[semicolo]

A) shouldn't be too hard, getting serial data and sending back to hid usb should be achievable on an avr or other micro.
B) Is more work than A) without any gain, so no.
C) Is more work than A) since you don't know how to write drivers.
D) sounds reasonable if you take into account that you may need 10hours of work to complete A)

[nes]

If it's bluetooth you want, why not hook it directly to a bluetooth serial module? There appear to be many low-cost ones to choose from on Ebay. I would pick one that uses the CSR chipset as I have used that one before and it works ok.

If you're going to pair it with an Android device, it should just work as a keyboard. If you want to use it with a Linux box, it should also do what you want. I don't think you'll be able to use it as an ordinary keyboard with a Windows PC without much faffing with extra software though.

Also, for a simple serial to USB keyboard adapter, maybe check out http://www.1010.co.uk/org/byron.html as a starting point and modify it to suit your needs. (The Palm keyboard has keys you won't find on a PC, and vice-versa, so you'll need to make some decisions how to map them.)

[st2000]

Hey, I posted this very same question / project here (maybe) a year ago. But didn't get anywhere with the project. Here's why...

1. Bluetooth. There are serial (a) bluetooth modules and (b) bluetooth keyboards chips.

(a) The problem with the serial bluetooth modules is that they are not USB/HIDs at the far end. No, they are serial ports. That's not going to work. You need to emulate a keyboard at the far end of the bluetooth connection. True, you can further add a micro to do this. Ok, but now you added two bluetooth transceivers and a micro to change the serial signal coming out of the keyboad into a USB/HID keyboard signal.

(b) The problem with the bluetooth keyboard chips are that they interface with the keyboard using a matrix. That is, if your keyboard is not aligned with (built) the way the bluetooth chip expects to see the keys of the keyboard laid out in a matrix - well, you might as well start over with plain switches for each key.

2. Direct connection. Sure you can grab your self a micro and convert the serial port data to USB/HID. Such an interface is well with in the capabilities of many of microchip.com PICs (i.e. we are not talking USB/HOST which takes a powerful lot of hardware and software to run). And their free samples of code will give you a good foundation to start with. In fact, I am sure there is an example where a USB/HID mouse is emulated. You could probably draw power off the USB port of the PC you are connecting to to power both the PIC and the Keyboard. BTW, yes, this keyboard does use a bit of power from the Palm Pilot.

I really liked this keyboard. It is by far the best portable keyboard I have owned. And I have plenty (at least 3 different bluetooth based designs). I am sure I paid over $100 for it new. It is a shame I have never been able to conjure up way to make this into a bluetooth keyboard both economically and with out increasing the size unreasonably.

I thought it pointless to make this into a wired keyboard since the computer you might use this with is either not portable or is and happens to have its own keyboard (i.e. a laptop). And the bluetooth solutions I found did not work because of the above mentioned problems.

So my keyboard sits - still waiting for the perfect set of chips or application.

BTW, I didn't open my keyboard. After a certain point, it is almost all stickers and glue. If you dare to do what I have not do take pictures and post. I have not mapped out the keyboard. Maybe, just maybe, it matches a cheap bluetooth keyboard of which I wouldn't think twice of harvesting parts from. In that case, yes, it would be possible and cheaply too to convert this keyboard into a bluetooth keyboard.

Do let us know what you make of your keyboard.

-good luck

Edit: added later...

Ok, now I am confused. The PDF you pointed to has, interestingly, "the key lay out". Now I'll have to break out my broadcom bluetooth specifications to see if there is a match. But, but, that document also talks about transmitting the shift key. From my recollection that was not the case. Instead the keyboard would transmit out the ASCII capital "A" for instance. It would never transmit the shift then the "a" let alone the up or down position of any particular key. Something funny here.

[st2000]

I was going to use this chip / module that I would harvest from an inexpensive (~$20) bluetooth keyboard.

http://pdf1.alldatasheet.com/datasheet-pdf/view/175090/BOARDCOM/BCM2042.html

But as you can tell, Broadcom is very very stingy with specifics. If any have the real data sheet on this chip/ module I would appreciate seeing it. So, the specifics of the keyboard matrix for the BCM2042 is a mystery. Sure, you can backwards engineer it using the inexpensive keyboard, but it would be tedious work.

So far it has be much easier just to buy new bluetooth keyboards. The ones HP dumped for their discontinued TouchPad are great. They are practically copies of the Apple bluetooth keyboards except black instead of white.

Regardless, the thinkoutside fold able keyboards are sought after devices. And this is long after thinkoutside switch to selling cheap pacific rim products - dropping keyboards all together. Humm.