2 layers69.2 × 128.5 mm
Ctrl+alt rev0
backtail/ctrl-alt
6 HP Eurorack module and corresponding embedded framework
149 partsCERN-OHL-S-2.0
2 layers69.2 × 128.5 mm
Ctrl+alt rev1
backtail/ctrl-alt6 HP Eurorack module and corresponding embedded framework
- Size
- 69.2 × 128.5 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 147
- Nets
- 91
- Pads
- 385
- Tracks, vias
- 686, 89
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 15 Dec 2024
- Updated
- 22 Jun 2025
Overview
Ctrl+alt rev1 is an open-source printed circuit board by backtail, from the backtail/ctrl-alt repository on GitHub, published under the CERN-OHL-S-2.0 licence. It is a 2-layer board of 69.2 × 128.5 mm with 147 parts on 91 nets, routed with 686 tracks and 89 vias.
It is built around the STM8S105K6T6C, LM358 and TMUX4053PW, with the 1N5819WS and BC847 among its other parts. Its parts include 38 capacitors, 37 resistors, 17 diodes, 11 connectors and 7 ICs. It belongs with the audio and music boards and the STM8 boards of this library.
Main components
5
STM8S105K6T6C
LQFP-32(7x7)-40℃~+85℃ 10bit 16MHz 1KB 2.95V~5.5V 25 2KB 32KB 8 Bit Built-in FLASH STM8 LQFP-32(7x7) Microcontrollers (MCU/MPU/SOC) ROHSSTMicroelectronicsMicrocontrollers (MCU/MPU/SOC)
LM358
SOP-8-18V~18V 0℃~+70℃ 1.2MHz 10nA 2 24mA 3V~36V 500uA 50nA 5mV 80dB Built-in compensation SOP-8 Operational Amplifier ROHSMSKSEMIOperational Amplifier
TMUX4053PW
TSSOP-16-12V~12V、5V~24V -55℃~+125℃ 1.05kΩ 140ns 190ns 20ns 2:1 3 5pF 850MHz TSSOP-16 Analog Switches, Multiplexers ROHSTexas InstrumentsAnalog Switches, Multiplexers
1N5819WS
SOD-3231 Independent 1A 25A 40V 500uA@40V 600mV@1A SOD-323 Schottky Diodes ROHSGuangdong HottechSchottky Diodes
BC847
SOT-231 NPN 100MHz 100mA 100nA 110 200mW 45V 500mV 6V NPN SOT-23 Bipolar (BJT) ROHSShikuesBipolar (BJT)
README
README.mdCTRL+ALT
CTRL+ALT is a modular firmware and hardware platform for a STM8 microcontroller, focused on real-time audio, control voltage (CV), and lo-fi digital signal processing. It is designed for experimentation, eurorack synths and embedded control projects.
Currently, the framework comes with these example projects to help you get started and familiarise yourself on how to access the functionalities:
- blinky
- master clock
- sample & hold
- wavetable LFO
If you fork this repo and come up with your own cool program, feel free to contribute so that everyone can enjoy it!
Getting Started
Prerequisites
- PlatformIO (for building and uploading firmware)
- ctrl+alt eurorack module
- STM8 debug probe
- VSCode (optional, but really good integration and generally recommended for this project)
- VSCodium (optional, PlatformIO not natively supported, however workaround exists)
Getting Started
Install VSCode with PlatformIO Plugin (recommended) or the PlatformIO CLI tool.
$ git clone https://github.com/backtail/ctrl-alt
$ cd ctrl-alt
$ code . # open VSCodeAll example projects are located in src/programs/.
Building
Use the VSCode/Codium PIO task and set the right project/environment. (recommended)
or
$ pio run -e <project_name>Upload
Use the VSCode/Codium PIO task and set the right project/environment. (recommended)
or
$ pio run -e <project_name> -t uploadThe Complementary Hardware
This framework is made to run on the 6 HP wide CTRL+ALT eurorack module which can be found under hardware/.
It features:
- 3 logic inputs (threshold ~ 2.5V, 12V tolerable) + indicator LEDs
- 3 CV inputs (0V to 5V, 12V tolerable)
- 3 knobs
- up to 3 CV outputs (0V to 5V) or up to 3 logic outputs (0V or 5V) + indicator LEDs -> per output switchable via software
- 1 toggle switch
- 1 momentary button switch
Contributing
Please read CONTRIBUTING.md [blocked] for details on our code of conduct, and the process for submitting pull requests to us.
Authors
- Max Genson - Engineer @ KOMA Elektronik
License
The underlying hardware project source code is licensed under CERN Open Hardware Licence Version 2 - Strongly Reciprocal.
Everything else, including the source code of the firmware for the CTRL+ALT hardware is licensed under GPL-3.0.
Parts
147| Qty | Value | Footprint | References |
|---|---|---|---|
| 19 | 100n | Capacitor_SMD:C_0402_1005Metric | C101, C102, C103, C104, C105, C106, C124, C125, C126, C127, C128, C129, C130, C131, C132, C133 +3 |
| 9 | 1N5819WS | Diode_SMD:D_SOD-323 | D101, D102, D103, D104, D105, D106, D113, D114, D115 |
| 9 | Thonkiconn | Genson_Jacks:Jack_3.5mm_Thonkiconn | J101, J102, J103, J104, J105, J106, J107, J108, J109 |
| 8 | 10k | Resistor_SMD:R_0603_1608Metric | R102, R107, R110, R113, R118, R130, R132, R137 |
| 8 | 2k2 | Resistor_SMD:R_0603_1608Metric | R123, R124, R125, R131, R133, R134, R135, R136 |
| 8 | red | Genson_LEDs:LED_D1.8mm | D107, D108, D109, D110, D111, D112, D116, D117 |
| 6 | 1k | Resistor_SMD:R_0603_1608Metric | R103, R104, R105, R127, R128, R129 |
| 5 | LM358 | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U101, U102, U103, U104, U105 |
| 3 | 100k | Resistor_SMD:R_0603_1608Metric | R101, R106, R126 |
| 3 | 100k | Genson_Potentiometers:Potentiometer_RK09_RV09_Vertical | RV101, RV102, RV103 |
| 3 | 150p | Capacitor_SMD:C_0402_1005Metric | C110, C115, C120 |
| 3 | 1n | Capacitor_SMD:C_0402_1005Metric | C108, C113, C118 |
| 3 | 1n5 | Capacitor_SMD:C_0603_1608Metric | C107, C112, C117 |
| 3 | 200k | Resistor_SMD:R_0402_1005Metric | R111, R116, R121 |
| 3 | 24V/200mA | Resistor_SMD:R_0805_2012Metric | F101, F102, F103 |
| 3 | 27k | Resistor_SMD:R_0402_1005Metric | R108, R114, R119 |
| 3 | 330p | Capacitor_SMD:C_0402_1005Metric | C109, C114, C119 |
| 3 | 47p | Capacitor_SMD:C_0402_1005Metric | C111, C116, C121 |
| 3 | 560k | Resistor_SMD:R_0603_1608Metric | R112, R117, R122 |
| 3 | 75k | Resistor_SMD:R_0402_1005Metric | R109, R115, R120 |
| 3 | BC847 | Package_TO_SOT_SMD:SOT-23 | Q101, Q102, Q103 |
| 2 | 22n | Capacitor_SMD:C_0402_1005Metric | C122, C138 |
| 2 | 4u7 | Capacitor_SMD:C_0805_2012Metric | C123, C137 |
| 1 | Genson_Scribbles:silkscreen_alien_small | ||
| 1 | Debug | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J111 |
| 1 | LOGO | LOGO | G*** |
| 1 | STM8S105K6T6C | Package_QFP:LQFP-32_7x7mm_P0.8mm | U106 |
| 1 | SW_Push_DPDT | Genson_Switches:SW_5.8x5.8mm | SW102 |
| 1 | TMUX4053 | Package_SO:TSSOP-16_4.4x5mm_P0.65mm | U107 |
| 1 | power conn | Connector_PinHeader_2.54mm:PinHeader_2x08_P2.54mm_Vertical_SMD | J110 |
| 1 | reset | Button_Switch_SMD:SW_SPST_TL3342 | SW101 |
| 1 | trig | Genson_Switches:SW_PBS-110_Normally-Open_Push_Button | SW103 |
The 124 most common of 147 parts.
Questions
How big is the Ctrl+alt rev1 PCB?
It measures 69.2 × 128.5 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Ctrl+alt rev1 use?
147 parts, built around the STM8S105K6T6C, LM358, TMUX4053PW and 1N5819WS. 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 Ctrl+alt rev1 KiCad files?
From the backtail/ctrl-alt repository on GitHub, at the commit this page was made from: the board is hardware/rev1/ctrl+alt_rev1.kicad_pcb and its schematic hardware/rev0/ctrl+alt_rev0.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Ctrl+alt rev1 design in my own project?
Its repository publishes it under the CERN-OHL-S-2.0 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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