Custom HID: Mini Editing Keyboard

thingiverse

**Introduction** This is a custom mini-keyboard prototype driven by an Arduino Pro Micro, designed for editing text on smartphones or tablets. The code controls keys for arrows, shift+left/right arrows (text selection), home, select all, copy/paste, undo/redo, and delete. However, you can redesign the keyboard to do anything with Arduino's Keyboard Modifiers guide: https://www.arduino.cc/en/Reference/KeyboardModifiers. It's a prototype intended to gather user experience and determine where to go from here. **Parts** * 13 mini-push button switches (4 pins, 2.5mm tall button) * 2 M3 x 15mm bolts and nuts * 2 M3 x 10mm bolts and nuts * 1 Arduino Pro Micro * 1 Perfboard cut to 46x79mm * 1 USB-micro-USB cable with OTG adapter Your OTG adapter depends on the device you're using. If it's for a desktop, use the standard USB cable; others require micro-USB or Type-C adapters. **Electronics** The circuit is simple and tedious to solder, but worth the effort. Connect two pins from each mini-push button to corresponding i/o pin and GND (ground) on the Arduino. Test the circuit using jumper wires first to ensure everything works. Then cut perfboard to 46x79mm, assemble buttons and Arduino onto it, and test fit before soldering anything. We used wires for left legs and solder tracing to connect ground legs together and to a single GND pin on the Arduino. **Programming** We've included the INO file. Rearrange the "define" section for clarity; our version reflects a wiring mistake. If you make a similar error, simply change the pin number or switch assignment in the code. Use a multimeter's continuity function to verify connections and ground arrangements. **Assembly** * Friction weld or glue M3 nuts into space on the back of the front cover * Place the electronics board on support rails of the back cover * Insert keys through key openings on the front case * Assemble the back cover with electronics on top of the front case * Drive bolts into the back cover We designed the keys for forgiving indentation, allowing for slight imperfections in perfboard cuts or button seating. **Operation** Plug a micro-USB/USB cable into the Arduino's exposed micro-USB port and the other side into your mobile device using an OTG adapter.