2 layers193.8 × 100 mm
2 layers165.1 × 100 mm
Left split
nano13579/banana-splithotswappable wireless split keyboard
- Size
- 165.1 × 100 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 64
- Nets
- 58
- Pads
- 316
- Tracks, vias
- 469, 72
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 30 Jun 2025
- Updated
- 29 Oct 2025
Overview
Left split is an open-source printed circuit board by nano13579, from the nano13579/banana-split repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 165.1 × 100 mm with 64 parts on 58 nets, routed with 469 tracks and 72 vias.
Its parts include 31 diodes, 31 switches and 1 IC. It belongs with the keyboards and input boards and the nRF52 and nRF5x boards of this library.
README
README.mdBanana Split
About
With a design similar to that of the UM-70, this split keeb is hotswappable, wireless, and ZMK supported. Both halves fit together like puzzle pieces and are powered by 3.7v rechargeable lithium ion batteries. The current case is made of a simple sandwich mount with openings for USB-C connection. I made this primarily because I wanted to make something unique and different from common split custom keyboard designs - I also learned a ton about matrixes and the functionality behind wireless split keebs in the process.
Things I Missed
In the current design, there are no neopixels, rotary encoders, OLED screens, etc. because I was lazy but future iterations may include these features! There are also no current features for wrist support - so this might be added later as well. Stabiliziers aren't in the cad right now, but do fit into case & pcb.
Please note that a few footprints at the edge of the right hand keeb are upside down so that edge cut restrictions would not change dimensions. Therefore, all keycaps should be PBT OEM so as to not obstruct typing - although this is not shown in the design
Parts
64| Qty | Value | Footprint | References |
|---|---|---|---|
| 31 | 1N4148 | Diode_THT:D_DO-35_SOD27_P7.62mm_Horizontal | D1, D2, D10, D11, D12, D13, D14, D15, D16, D17, D18, D19, D20, D21, D22, D23 +15 |
| 24 | SW_Push_45deg | kailhv4:MX-Hotswap-1U | SW1, SW2, SW10, SW11, SW12, SW13, SW15, SW16, SW17, SW18, SW19, SW20, SW22, SW23, SW24, SW25 +8 |
| 2 | SW_Push_45deg | kailhv4:MX-Hotswap-1.25U | SW28, SW29 |
| 2 | SW_Push_45deg | kailhv4:MX-Hotswap-1.5U | SW7, SW30 |
| 1 | Battery_Cell | Connector_JST:JST_PH_S2B-PH-K_1x02_P2.00mm_Horizontal | BT1 |
| 1 | Nice_Nano_V2 | scotto:Nice_Nano_V2 | U1 |
| 1 | SW_Push_45deg | kailhv4:MX-Hotswap-1.75U | SW14 |
| 1 | SW_Push_45deg | kailhv4:MX-Hotswap-3U | SW31 |
| 1 | SW_Push_45deg | kailhv4:MX-Hotswap-2.25U | SW21 |
Questions
How big is the Left split PCB?
It measures 165.1 × 100 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Left split use?
64 parts. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Left split KiCad files?
From the nano13579/banana-split repository on GitHub, at the commit this page was made from: the board is pcb/left_split/left_split.kicad_pcb and its schematic pcb/left_split/left_split.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Left split design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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