🧽 Sessile

Sessile is a further exploration of "minimal" finger travel.

🤔 What Even Is 'Minimal Finger Travel' Anyway?

Probably the least amount of finger travel would be not moving them at all. That would be 10 keys...

$$combos_{10\,keys} = \sum_{r=1}^{10} C(10, r) = 1023$$

...yielding 1023 possible combinations.

More realistically, we might consider excluding cross hand combinations so that modifiers might be used. That would give us

$$combos_{5\,keys} = \sum_{r=1}^{5} C(5, r) = 31$$

So, with only 5 keys on both hands, and no cross hand combos, we would have a total of 62 possible keys per layer—more than sufficient.

I wasn't quite ready to take on learning to type on that though, so just avoiding lateral reaches seemed like a start. 🙃

✨ Features

• 🧩 Sessile uses KLP-Lame keycaps. Larger caps may be tight, especially on the bottom row. I was lazy and didn't model the tilted keycaps in the rendering, but they're much nicer for the vertical combos.

• 🔋 Uses battery LIR1254. DO NOT substitute LR44.

• 🔌 The high speed pins were left available for encoders and could be wired in a subsequent revision.

• ⚙️ Built for RMK. Configure using Vial.

🏠 Case

A 3D printable case is available in the latest release! The case is designed to sit as low as possible and can be secured with a stroke of glue stick underneath. Case is generated via ergogen with jscad v2 api. Try it out it's testing 10-20x faster than @jscad/cli@1.

📦 Production Files

Ready to manufacture your own board? All production files are included in the repository:

Includes gerbers, BOM, and CPL files for JLC. Finished boards are available sold out till the next batch.

🎨 Origin

Sessile was produced using studyofhands.

🚀 Firmware

This board is designed for RMK. 😏

🦀 RMK

Current RMK build is available in the Releases.

You can build the firmware yourself by cloning this repository and running

cd rmk && cargo make uf2 --release

Tip

If you haven't previously used Rust to build software for nRF52840, you may need to follow the Setup RMK Environment instructions.

🗺️ Keymap

Generated with keymap-drawer.

Physical layout imported from KiCad via keymap-layout-tools.

🔌 Matrix Diagram

Sessile uses the following pinout for its matrix:

Note

Referencing this pinout sheet provided by Seeed, the only two exposed high speed pins P0_04/SDA/D4 & P0_05/SCL/D5 have been left available for possible encoders in a subsequent revision.