

Main3
YUIOP: Etude of designing keyboards
- Size
- 285 × 94.6 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 207
- Nets
- 161
- Pads
- 1,062
- Tracks, vias
- 1,908, 57
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 5 (file 20171130)
- Created
- 10 Jan 2021
- Updated
- 31 Jan 2026
Overview
Main3 is an open-source printed circuit board by koron, from the koron/yuiop repository on GitHub, published under the MIT licence. It is a 2-layer board of 285 × 94.6 mm with 207 parts on 161 nets, routed with 1,908 tracks and 57 vias.
It is built around the 1N4148W, WS2812C-2020-V1 and BSS138. Its parts include 116 diodes, 4 capacitors, 4 connectors, 2 resistors and 1 IC. It belongs with the keyboards and input boards of this library.
Main components
31N4148W
SOD-123150mA 1A 1V@50mA 1uA@75V 400mW 4ns 75V Independent SOD-123 Switching Diodes ROHSSTMicroelectronicsSwitching DiodesWS2812C-2020-V1
SMD,2x2mm0.5mA 0.84mm 2.2mm 2kHz 2mm 3.7V~5.3V 800Kbit/s Built-in power-on reset circuit、Built-in power-on reset circuit G:520nm、R:624nm、B:467nm R:130mcd、G:320mcd、B:60mcd SMD,2x2mm RGB LEDs(Built-in IC) ROHSWorldsemiRGB LEDs(Built-In IC)BSS138
SOT-23-55℃~+150℃ 1 N-channel 1.1Ω@10V、1.2Ω@4.5V 1.2V 1.7nC@10V 17.5pF 340mA 350mW 50V 6.5pF N-Channel SOT-23 MOSFETs ROHShongjiachengMOSFETs
README
README.mdYUIOP Keyboard series
YUIOP keyboards are experimental original keyboards designed by KoRoN.
Sub Projects
Keyboards in this project are:
-
yuiop27/ - separate keyboard prototype.
27 keys for one hand. single left hand.
-
yuiop54/main - signle board keyboard prototype.
combined right and left-hand boards of yuiop27. PCB dimension is 285.00mm x 94.60mm (GH60 compatible form factor without screw holes).
-
yuiop54/main2 - researching version of yuiop54.
multi-sheets schematic. fix layout for auto routing. introduce GND cupper fill.
-
rev.B - trial to make compatible with GH60 (include screw holes).
use popular keycaps size. tring 128x64 dots OLED.
-
rev.C - key sizes revised version.
consider just layout. use 1u footprint for keys of little fingers. compact form factor size, 267.00mm x 95.00mm (drop compatibility with GH60). change the origin to center of PCB. use 2u for R5 center key. use Edge.Cuts to represents screw holes. OLED is 128x32 dots.
-
rev.D - narrowwer version of rev.C
consider just layout. the dimension is 262.0mm x 95.00mm reduce margins between
FandGkeys, andHandJkeys. -
rev.E - a variation of rev.C
the dimension is 267.00mm x 95.00mm (same with rev.C, not rev.D) make keys on
F's row be able to use 1.25u keycap.
-
-
yuiop47/ - Single board keyborard with 47 keys.
Shrink from yuiop54. PCB dimension is 214.00mm x 94.00mm
-
yuiop60hh/main - HHKB clone trial
- main2 - HHKB clone trial #2
- main3
- main4
- main5 - Practicing version
- main5b - USB Type-C receptacle version of main5
-
yuiop50d/ - Small footprint, dense 50 keys keyboard.
1u is 16mm, using small keycaps. Standard row staggered layout. Support Pro Micro and RapsberryPi Pico as MCU. PCB dimension is 182.00mm x 103.50mm
-
yuiop63hhs/ - Split HHKB layout minimal keyboard.
No LED nor OLED, Just 63 (29+34) keys. PCB dimension 319.00mm x 95.00mm
- Left 152.50mm x 95.00mm
- Right 162.00mm x 95.00mm
-
yuiop22rs/ - 22 keys + rotary switch macropad.
With OLED, without LED. PCB dimension 95.25mm x 95.25mm
-
contorller/ - Keyboard controler using ATmega32U4 which replacing Pro Micro.
-
yuiopPM/ - Pro Micro compatible but minimal for only keyboard, PCB
-
yuiopPM2/ - Revised version of yuiopPM. It was shelved unfinished.
-
yuiop60hh/main3 - HHKB layout, compatible with popular 60% cases.
Problems on positions of screw hole or so. Not built.
-
yuiop60hh/main4 - HHKB layout, compatible with popular 60% cases.
YUIOP60HH series revision 4. Implemented with MPU ATmega32U4 (not Pro Micro)
-
yuiop31rs/ - 31 keys + rotary switch macropad.
With 31 LEDs (WB2812C-2020). Its hole is too small to be chaged extra on production.
-
yuiop60s/ - split keyboard prototype
-
yuiop60pi/ - PGA2040 (RP2040) base HHKB layout semi-compatible keyboard.
-
yuiop2040/ - Original RP2040 control board.
-
yuiop2040C/ "Compact" model of yuiop2040. Abandoned.
-
yuiop32dm/ - Experimental keyboard for Duplic Matrix
-
yuiopPD/ - Pointing device using the trackball module of Keyball series.
-
rp2040-controller/ - Reusable circuit diagram for controller using RP2040
Parts
207| Qty | Value | Footprint | References |
|---|---|---|---|
| 60 | 1N4148W | yuiop:D_SOD-123 | D1, D2, D10, D11, D12, D13, D14, D15, D16, D17, D18, D19, D20, D21, D22, D23 +44 |
| 60 | MX_HOTSWAP | yuiop:Cherry_MX_Hotswap_1.0u_v2 | KSW1, KSW2, KSW10, KSW11, KSW12, KSW13, KSW14, KSW15, KSW16, KSW17, KSW18, KSW19, KSW20, KSW21, KSW22, KSW23 +44 |
| 56 | WS2812C-2020 | yuiop:LED_WS2812C-2020_BackMount_v2 | LED1, LED2, LED10, LED11, LED12, LED13, LED14, LED15, LED16, LED17, LED18, LED19, LED20, LED21, LED22, LED23 +40 |
| 6 | Hole_2.2_4 | yuiop:Hole_2.2_4 | HOLE7, HOLE8, HOLE9, HOLE10, HOLE11, HOLE12 |
| 4 | 10u | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C2, C3, C4 |
| 3 | Hole_5x2.3_6 | yuiop:Hole_5x2.5_7 | HOLE1, HOLE2, HOLE4 |
| 2 | 10K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R2 |
| 2 | Cherry_MX_Stabilizer | yuiop:Cherry_MX_Stabilizer | STB1, STB3 |
| 2 | Hole_7x2.5 | yuiop:Hole_7x2.5_10x5 | HOLE5, HOLE6 |
| 1 | BSS138 | Package_TO_SOT_SMD:SOT-23 | Q1 |
| 1 | Cherry_MX_Stabilizer_6.25u | yuiop:Cherry_MX_Stabilizer_6.25u | STB2 |
| 1 | DEBUG | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J3 |
| 1 | D_Schottky | Diode_SMD:D_SOD-123 | DS1 |
| 1 | Fuse | Fuse:Fuse_1206_3216Metric_Pad1.42x1.75mm_HandSolder | F1 |
| 1 | Hole_2.3 | yuiop:Hole_5x2.5_7 | HOLE3 |
| 1 | LOGO | project:QR_README | G1 |
| 1 | PGA2040 | yuiop:PGA2040 | U1 |
| 1 | RESET | Button_Switch_SMD:SW_Push_1P1T_NO_6x6mm_H9.5mm | RSW1 |
| 1 | UART | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J4 |
| 1 | USB_B_Micro | Connector_USB:USB_Micro-B_Amphenol_10103594-0001LF_Horizontal | J1 |
| 1 | USB_MON | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J2 |
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Questions
How big is the Main3 PCB?
It measures 285 × 94.6 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Main3 use?
207 parts, built around the 1N4148W, WS2812C-2020-V1 and BSS138. 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 Main3 KiCad files?
From the koron/yuiop repository on GitHub, at the commit this page was made from: the board is yuiop60pi/main3/main3.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Main3 design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).