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St40

coarse·st40

St40 PCB layout, top view — open source STM32 board by coarse
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About the St40 PCB

St40 is an open source STM32 PCB design by coarse, published on GitHub under the CC-BY-SA-4.0 license. It is a 2-layer board measuring 226.1 × 73.9 mm, with 110 components from 11 distinct parts.

Its main chip is the STM32F072CBTx, from the STM32 family. Other key parts include the LD1117S33TR_SOT223. By type, the board carries 49 LEDs, 48 diodes, 7 capacitors, 2 ICs, 2 switches and 1 connector.

It belongs with the keyboards designs in this gallery.

From the project

Open source 40% ortholinear keyboard PCB powered by STM32F072

- Planck-like layout - South-facing LED (even though there is no backlight) because that's how switches were meant to be oriented - No backlight, no underglow - No fancy ESD protection - No fancy reset circuit - USB Mini because literally no frills - STM32F072CBT6

- KiCad 5.0.1 - Default KiCad Schematic Library - ai03's Switch Footprint Library (included as submodule)

St40, from the project README
From the project README

Main components on the St40

LD1117S33TR_SOT223STM32F072CBTx

St40 bill of materials (BOM)

110 components, 11 distinct parts.

QtyPartRefs
1
LD1117S33TR_SOT223
U1
1
STM32F072CBTx
U2
1
USB_B_Mini
J1
2
SW_SPST
SW1, SW2
48
MX-1U
MX1, MX2, MX3, MX4, MX5, MX6, MX7, MX8 +40
1
MX-2U
MX49
48
SOD-123
D1, D2, D3, D4, D5, D6, D7, D8 +40
1
4.7uF
C1
5
100nF
C2, C3, C4, C5, C7
1
10uF
C6
1
R_Small
R1

St40 design files

The KiCad project lives in the coarse/st40 repository on GitHub; these links point at the commit this page was built from.

St40: common questions

What microcontroller does the St40 use?

The St40 is built around the STM32F072CBTx, from the STM32 family.

How big is the St40 PCB?

The St40 measures 226.1 × 73.9 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the St40?

110 components, from 11 distinct parts. The full bill of materials is listed on this page.

Where can I download the St40 design files?

From the coarse/st40 repository on GitHub, which has the KiCad layout; the links under Design files point to each one.

Can I use the St40 design in my own project?

Yes, under the terms of its CC-BY-SA-4.0 license, which coarse chose for the repository.

Can I test firmware for the St40 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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