My take on the old “re-purposing a dead Psion 5’s keyboard as a USB keyboard” 😉
(made from a box of dead Psions from eBay)
(Not my first retro keyboard –> USB project)
I’m using RasmusB’s keyboard-matrix-USB adapter from Tindie, I’ve hacked up his firmware to add support for all the symbols printed on the front edge of the keycaps and altered the function of the LED to mimic capslock on the host… which is nicely lined up to shine through the standard LED lens/window in the keyboard 🙂 Obviously mounting the keyboard as I have with the back edge at a slightly raised angle in the empty base of a dead S5 means there’s lots of room in there for batteries and a different micro-controller (Pi Pico 2 W?) to add Bluetooth at some later date….?
As an added bonus using the empty bottom half of the Psion case provides rubber feet to stop the little keyboard slipping around too 🙂
Other Psion-5 keyboard+USB+Bluetooth projects:
https://jbmorley.co.uk/projects/psiboard/
https://www.reddit.com/r/umpc/comments/lj5kkl/bluetooth_keyboard_based_on_psion_5_keyboard/
Had to set this one up for the camera 😉
This is just the Psion-USB keyboard plugged into an iPad holder/USB hub plugged into my Android phone running the wuffs.org 5mx emulator…
Room 7609 
Super cool. Are you making more of them? I’ve always thought that the Psion5 keyboards would make great bluetooth keyboard and charging case. EG add a lipo both for the keyboard’s electronics and to charge the phone when holstered.