HardLabs

UnMechanical

ebastler·UnMechanical·unmechanical-sweepish/unmechanical-sweepish.kicad_pcb

UnMechanical PCB layout, top view — open source STM32 board by ebastler

About the UnMechanical PCB

UnMechanical is an open source STM32 PCB design by ebastler, published on GitHub under the CERN-OHL-P-2.0 license. It is a 4-layer board measuring 214 × 145.5 mm, with 156 components from 33 distinct parts.

Its main chip is the STM32G431CBU6, from the STM32 family. Other key parts include the XC6206P332MR, SRV05-4, OPA340NA and 74HC4051. By type, the board carries 44 resistors, 36 capacitors, 14 diodes, 10 ICs, 6 connectors and 2 transistors.

It belongs with the keyboards designs in this gallery.

From the project

Capacitive touch keyboard running QMK firmware

The operating principle is pretty much unchanged from the EC boards by cipulot. Basically, the columns are strobed by the MCU, and the capacitive touchpad forms a capacitive voltage divider together with a 220pF resistor on the PCB. The voltage over the capacitor is measured to determine the capacity of the touchpad, which strongly changes if the pad is touched.

UnMechanical, from the project README
From the project README

Main components on the UnMechanical

XC6206P332MRSRV05-4STM32G431CBU6OPA340NA74HC4051

UnMechanical bill of materials (BOM)

156 components, 33 distinct parts — part numbers from the project's BOM.

QtyPartRefs
2
XC6206P332MR
XC6206PxxxMR
Torex Semiconductor
U1, U6
2
SRV05-4
U2, U7
2
STM32G431CBU6
STM32G431CBUx
STMicroelectronics
U3, U8
2
OPA340NA
Texas Instruments
U4, U9
2
74HC4051
U5, U10
2
AO3400A
Alpha & Omega Semiconductor
Q1, Q2
1
HTP-CON-M411P-F
HytePro M
HytePro
J1
2
TYPE-C-31-M-14
USB_C_Receptacle_USB2.0
HRO Koreaparts
J2, J5
2
M
J3, J6
1
HTP-CON-M411P-M
HytePro F
HytePro
J4
36
EC
EC1, EC2, EC3, EC4, EC5, EC6, EC7, EC8 +28
2
BSMD0603-050-6V
Polyfuse
BHFUSE
F1, F2
2
JP
JP1, JP2
2
SKQGAKE010
B/R
Alps Alpine
SW1, SW2
4
DS14W
D_Schottky
D1, D2, D8, D9
8
1N4148WT
D3, D4, D6, D7, D10, D11, D13, D14
2
SMF3.3
D5, D12
2
BLM15PX121SN1D
MuRata
L1, L2
4
4U7
4u7
C1, C7, C19, C25
8
1u
C2, C3, C11, C13, C20, C21, C29, C31
Show 13 more
QtyPartRefs
2
10U
10u
C4, C22
16
100N
100n
C5, C6, C8, C9, C10, C14, C17, C18 +8
2
10N
10n
C12, C30
2
DNP
C15, C33
2
220P
220p
C16, C34
16
100R
R1, R2, R4, R8, R9, R10, R11, R12 +8
2
4R7
R3, R25
8
10K
10k
R5, R6, R7, R13, R27, R28, R29, R38
2
100K
100k
R14, R35
2
DNP
R15, R36
2
1k
R16, R37
8
100K
100k
R17, R18, R19, R20, R39, R40, R41, R42
4
4K7
4k7
R21, R22, R43, R44

UnMechanical design files

The KiCad project lives in the ebastler/UnMechanical repository on GitHub; these links point at the commit this page was built from.

UnMechanical: common questions

What microcontroller does the UnMechanical use?

The UnMechanical is built around the STM32G431CBU6, from the STM32 family.

How big is the UnMechanical PCB?

The UnMechanical measures 214 × 145.5 mm, has 4 copper layers and is 1.6 mm thick.

How many components are on the UnMechanical?

156 components, from 33 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the UnMechanical design files?

From the ebastler/UnMechanical repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.

Can I use the UnMechanical design in my own project?

Yes, under the terms of its CERN-OHL-P-2.0 license, which ebastler chose for the repository.

Can I test firmware for the UnMechanical without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug STM32 firmware against it before you order a PCB.

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