Note: This will be updated with pictures and such soon
I have a thing for miniture keyboards, especially if they fold or slide. So when I found the particular style of PDA keyboard of the Dell Axim X3 and X5, as well as the Belkin G700 PDA keyboard made for the Toshiba e330/e335/e740, I was fairly excited. After feeling how satisfying the slide and keypresses were, I decided to give reverse engineering the protocol a try as they were only designed for particular PDAs.
I picked up a few of this style of PDA keyboard, and found minor variations between the versions. I decided to go with a Dell Axim X5 keyboard as there were only 3 connections between the keyboard itself and the PDA connector, two of which were power and ground (and they were labeled, a luxury).
First off was a disassembly of the PDA connector and power plug, I desoldered the connections leading from the keyboard controller that connect to PCB the connector is mounted on. Reassembled the frame and had a convenient 3 wires poking out.
If you’d like to try out one of these keyboards yourself, there tend to be several Dell Axim X3/X5 keyboards available on ebay in the $5-10 range (*Protip: search for G7L1-001).