chitin

📚 Table of Contents

• ⚠️ Disclaimer
• ⌨️ Welcome
• ⚙️ Features
• 💾 Firmware
• 📦 Parts List
• 🛠️ Build Images
• 📄 License

⚠️ Disclaimer

This project has reached the fully working prototype stage. All core features have been tested and function as intended. However, as with any DIY hardware project, you should carefully review all files before manufacturing or assembly. The author(s) cannot guarantee flawless operation in every environment or configuration.

The author(s) take no responsibility for any damage, issues, or legal trouble that might result from using this project (see the license). Be sure to follow local laws regarding radio frequencies and DIY electronics.

⌨️ Welcome

Chitin is a custom mechanical keyboard designed for ergonomic comfort, wireless functionality, and useful features. All hardware and software aspects of this project are open source and documented in this repository. Best of all, the build is completely hot-swappable, meaning assembly and disassembly can be done with ease. This includes the microcontroller, switches, lipo battery, and even the trackball. The chitin keyboard is based off my original keyboard design: scyboard.

The trackball used in this build is a Pimoroni PIM447 breakout with a Qw/ST connector. The connector is useful because you can use the trackball without needing to solder the mounting holes to the microcontroller. Included on the chitin PCB is a footprint for a JST SH connector, which you can use to connect the trackball to the board.

⚙️ Features

• Ergonomic split layout
• ZMK firmware support
• USB-C connectivity & battery charging
• Bluetooth compatible
• Customizable keymaps, layers, and macros
• Trackball which can be programmed as a pointing device
• Layout and case design is declared using Ergogen
• KiCad traces auto-routed using Freerouting
• Open source
• Hot-swap and semi-modular

💾 Firmware

To get started, I recommend forking my personal repository for chitin here: zmk-config-chitin.

• To flash the keyboard, follow the flashing instructions in the ZMK docs.
• Making modifications to the keyboard can be done within the config folder.
• My build sets the central device to the right half of the keyboard, and the peripheral to the left half. Making changes to which half the trackball resides on, or excluding the trackball from the build requires many changes to the code in the chitin repository and source module.
• The chitin ZMK repository also uses my Pimoroni trackball driver module (derived from mwandzik's driver) here: zmk-driver-pim447.

📦 Parts List

I am not sponsored or affiliated with the vendors linked below. This is where I prefer to purchase my products.

Part	Quantity	Description	Purchase Link	Datasheet
Microcontroller	2	nice!nano v2.0	Nice Keyboarrds nice!nano v2.0	Nordic nRF52840
Pin Headers	4	Controller socketing system (4mm)	MAC8 spring-loaded pin headers	MAC8 spring-loaded pin headers specifications
Reset Button	2	Panasonic miniature momentary button	Panasonic Reset Button	EVQPUC02K
Power Switch	2	Alps miniature SPDT switch	ALPS Powr Switch	SSSS811101
Battery Connector	2	JST PH 2.0mm	JST Battery Jack	JST_PH_S2B-PH-K_1x02_P2.00mm_Horizontal
Battery	2	3.7V LiPo 1200mAh (w/ JST adapter)	Lithium Ion Polymer Battery - 3.7v 1200mAh	301230
Diode	57	SMD Diode	Semtech SMD Diodes	SOD-123
Hotswap Socket	57	Kailh MX PCB Socket	Kailh Hotswap Sockets	CPG151101S11
MX Switch	57	JWICK Linear Switches	JWK JWICK Linear Switches	MX Series Keyswitch
MX Keycap	57	55 x 1u, 2 x 1.5u	DSA Keycaps	DSA Keycap Project
M2x15 Standoff	18	Standoffs for plate	Newark M2x15 Standoff	Farnell Datasheet
M2x5 Screw	8	Screws to connect bottom case to top case	CO-RODE Screw Kit
M2x6 Screw	18	Screws for bottom case and top plate	CO-RODE Screw Kit
M2.5x8 Screw	4	Screws to hold trackball in top case	CO-RODE Screw Kit
M2x3 Insert Nut	8	Inserts for top cases	uxcell Knurled Insert Nuts
M2.5x2 Nut	4	Nuts to hold trackball in top case	Newark M2.5 Hex Nuts	Farnell Datasheet
Trackball Breakout	1	Pimoroni RGBW Trackball Breakout	Trackball Breakout by Pimoroni	Trackball Dimensions
Qwiic Connector	1	JST SH 4-pin Right Angle Connector	JST SH 4-pin Right Angle Connector (10-pack) - Qwiic Compatible	KAWEEI TECHNOLOGY 1.0MM WAFER 90 SMT TYPE REEL PACKAGE
Bottom Case	2	3D printed bottom case	Case Files Found Here
Top Case	2	3D printed top case (tb case for trackball)	Case Files Found Here

NOTE: The trackball replaces the position of 1 switch from the keyboard layout. If not incorporating a trackball in the build, add 1 quantity to each of the following parts:

• Diode
• Hotswap Socket
• MX Switch
• 1u MX Keycap

🛠️ Build Images

📄 License

This project is licensed under the MIT License. See the LICENSE file for details.