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Ctrl-M

nuess0r·ctrl-M

Ctrl-M PCB layout, top view — open source STM32 board by nuess0r
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About the Ctrl-M PCB

Ctrl-M is an open source STM32 PCB design by nuess0r, published on GitHub under the CERN-OHL-S-2.0 license. It is a 2-layer board measuring 171 × 50.5 mm, with 18 components from 11 distinct parts.

Its main chip is the STM32F072CBT6, from the STM32 family. Other key parts include the USBLC6-2SC6 and XC6206P332PR. By type, the board carries 8 capacitors, 4 resistors, 3 ICs, 2 connectors and 1 switch.

It belongs with the keyboards designs in this gallery.

From the project

Replacement controller for the famous IBM Model M keyboard based on the STM32F072 microcontroller. Supported by QMK.

This is a replacement controller for the famous IBM Model M keyboard based on the STM32F072 microcontroller. Goal is to get it upstream in QMK.

Work in progress, prototypes are working in Model M from 1989, there is a bug for the version from 1986 and test for other variants are outstanding.

Controller based on a STM32F072 chip and designed with KiCAD.

To make the controller as flexible as possible there are four possible LED and earth cable connectors. Also the PCB can be cut into a smaller variant that fits the later IBM/Lexmark variant.

Ctrl-M, from the project README
From the project README

Main components on the Ctrl-M

USBLC6-2SC6XC6206P332PRSTM32F072CBT6

Ctrl-M bill of materials (BOM)

18 components, 11 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
USBLC6-2SC6
U1
1
XC6206P332PR
U2
1
STM32F072CBT6
U3
1
CONN_01X16
Conn_01x16
J7
1
Conn_01x08
J13
1
SW_Push
SW1
2
4.7U
4.7u
C1, C3
5
100N
100n
C2, C4, C5, C6, C7
1
10N
10n
C8
1
1k
R1
3
120
R2, R3, R4

Ctrl-M design files

The KiCad project lives in the nuess0r/ctrl-M repository on GitHub; these links point at the commit this page was built from.

Ctrl-M: common questions

What microcontroller does the Ctrl-M use?

The Ctrl-M is built around the STM32F072CBT6, from the STM32 family.

How big is the Ctrl-M PCB?

The Ctrl-M measures 171 × 50.5 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Ctrl-M?

18 components, from 11 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 Ctrl-M design files?

From the nuess0r/ctrl-M 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 Ctrl-M design in my own project?

Yes, under the terms of its CERN-OHL-S-2.0 license, which nuess0r chose for the repository.

Can I test firmware for the Ctrl-M 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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