Long ago when digital portables where in their infancy, people were already loath to type on tinykeyboards ... what [Xinming Chen] did with their PPK Bluetooth adapter. Inspired by the work ...
One small point I noticed is that the keyboard can’t connect to a host device via USB. You must connect via Bluetooth or 2.4GHz RF. However, it’s possible to recharge the keyboard battery and ...
For a smallkeyboard, though, you’d probably be looking at an old Blackberry handset, one of those Bluetooth doohickies, or rolling your own like the fantastic Hackaday Belgrade badge.