building a corne split keyboard

It’s been a while since during a Hack-the-Planet episode I was gifted two PCBs of a corne keyboard by PH_0x17 of Nerdbude and ClickClackHack fame.

Since a picture says more than a thousand words, I give you the result first:

my crkbd based keyboard

This keyboard design is made from the ground up as open source and naturally is fully available as a GIT repository containing everything you need to start: PCB schematics, drawing, documentation and firmware source code.

It took me a couple of months to get all the required parts ordered and delivered. Many small envelopes with parts that seemlingly are only produced by a handful of manufacturers. But anyways: After everything had arrived and was checked for completeness my wife took the hardware parts into her hands and started soldering and assembling the keyboard.

And so this project naturally is split up between my wife and me in the most natural (to us) way: My wife did all the hardware parts – whilst I did the software and interfacing portion. (Admittedly there only was to be figured out how to get the firmware compiled and altered to my specific needs)


So make the jump over to the blog of my wife and enjoy the hardware portion over there. Come back for the software portion. I will only leave some pictures of the process here:


After putting the hardware together it was time to get the firmware sorted as well. This keyboard design is based upon the open source QMK (Quantum Mechanical Keyboard) firmware.

Conveniently QMK comes with it’s own build tools – so you will be up and running in no time. Since I had purchased Arduino ProMicro controllers I was good with the most basic setup you can imagine. As the base requirements for the toolchain where minimal I went with the machine that I had in front of me – a Raspberry Pi 4 with the standard Raspberry Pi OS.

These where the steps to get going:

  • get Python 3 and the qmk tool installed – I’ve chosen not to use the tool setup procedure but instead go with a separate clone of the QMK firmware repository.
python3 -m pip install --user qmk
  • clone the QMK firmware repository and get the QMK tool running (in the /bin folder of the firmware repository – it’s actually just a python script)
git clone
cd qmk_firmware
git submodule sync --recursive
git submodule update --init --recursive --progress
make crkbd:default
  • create your own keymap to work with. You gotta use the crkbd firmware options as a default for this keyboard. The command below will generate a subfolder with the name of your keymap in the keyboards/crkbd/keymaps folder with the default settings of the crkbd keyboard firmware.
qmk new-keymap -kb crkbd
  • build your first firmware by running the command below (note: btk-corne is the name of my keymap)
qmk compile --clean -kb crkbd/rev1/legacy -km btk-corne
success! The first firmware is compiled
  • now you can flash the firmware to both ProMicro controllers. The most straight forward way for me was using avrdude on the commandline. In my case the device is added as /dev/ttyACM0 and the compiled firmware named crkbd_rev1_legacy_btk-corne.hex.

    When you got all this information you need to plug in the ProMicro and trigger a reset by bridging Ground and the Reset Pin. If you added, like we did, a button for reset you can use this. After hitting reset the ProMicro bootloader will enter the state where it’s possible to be flashed. Reset it and THEN run the avrdude commandline.

    The full commandline is:
avrdude -p atmega32u4 -P /dev/ttyACM0 -c avr109  -e -U flash:w:crkbd_rev1_legacy_btk-corne.hex
  • (alternatively) you can also use QMK Toolbox to flash the firmware. Also works.

So now you know how to get the firmware compiled and running (if not, look here further). But most probably you are not happy with some aspects of your keymap or firmware.

By now you might ask yourself: Hey, I’ve got two ProMicros on one keyboard. Both are flashed with the same firmware. Into which of the two do I plug in the USB cable that then is plugged into the computer?

The answer is: by default QMK assumes that you are plugging into the left half of the keyboard making the left half the master. If you prefer to use the right half you can change this behaviour in the config.h file in the firmware:

You have to plug in both of them anyway at times when you want to flash a new firmware to them as you adjust and make changes to your keymap.

Thankfully QMK comes with loads of options and even a very useful configurator tool. I used this tool to adjust the keymap to my requirements. The process there is straightforward again. Open up the configurator and select the correct keyboard type. In my case that is crkbd/legacy. The basic difference between legacy and common is a different communication protocol between the two halves. This really only is important when features are used that require some sort of sync between the two haves – like some RGB LED effects. Since I did not add any LEDs to the build I go with legacy for now. Maybe I need some features later that require me to go with common.

The configurator allows you to set up the whole keymap and upload/download it as a .json file.

That .json file can easily be converted into the C code that you need to alter in the actual keymap.c file. Assuming that the .json file you got is named btk-corne.json the full commandline is:

qmk json2c btk-corne.json

Then simply take this output and replace the stuff in the keymap.c with it:

Now you compile and flash again. And if all went right you’ve got the new keymap and firmware on your keyboard and it’ll work just like that :)


So this is interesting: Normally a Windows program (executable) if you try to run it anywhere else will show a message “cannot be run here” and terminates.

Printing this message is actually done by a little program whos task is to only print out this very message. So it can be overwritten.

Michael Strehovský did exactly this, very impressively. He documented what he did to get the game “snake”, written in C#, running on DOS instead of the “does not run here” stub. In an executable file that would run both, on standard 90s MS-DOS as well as on Windows with the .NET Framework installed.

He used a quite elaborate toolchain – namely DOS64-stub.

You can read all of this in the full thread. I recommend a deeper dive, as it’s a great start to better understand the inner workings of your computer…

multi-Protocol to MQTT tool

When you are dealing with IoT protocols, especially at hobby-level, you probably came across the MQTT protocol and the challenge to have all those different devices that are supposed to be connected actually get connected – preferably using the MQTT protocol.

Recently this little project came to my attention:

OpenMQTTGateway project goal is to concentrate in one gateway different technologies, decreasing by the way the number of proprietary gateways needed, and hiding the different technologies singularity behind a simple & wide spread communication protocol: MQTT.


OpenMQTTGateway support very mature technologies like basic 433mhz/315mhz protocols & infrared (IR) so as to make your old dumb devices “smart” and avoid you to throw then away. These devices have also the advantages of having a lower cost compared to Zwave or more sophisticated protocols. OMG support also up to date technologies like Bluetooth Low Energy (BLE) or LORA.

Of course, there is a compatible device list…

FriendOS – OS concept in your browser

brace for marketing:

Friend OS, a modularfully-customizable operating system accessible via any device that can support a modern web browser, or Friend’s Android and iOS apps. Friend OS leverages Internet and blockchain technologies to offer all the features of a commercial operating system, but one that gives you access to a secure and private cloud-based virtual desktop anytime, anywhere, no matter what hardware or software you use.

So what does this all mean? It’s apparently a web application scaled up to behave and be used like an operating system. It encapsulates an application and directory/filesystem like concept and essentially lives in one of your browser windows.

As long as you’ve got a supported browser, all your apps and data will be accessible through this. They claim.

It’s interesting as there is a lot of open source in there and even some docker effort made to get it running. Seems abandoned / not updated at the time of writing, but it’s a nice concept to begin with anyways.

generative art: flowers

It started with this tweet about someone called Ayliean apparently drawing a plant based upon set rules and rolling a dice.

And because generative art in itself is fascinating I am frequently pulled into such things. Like this dungeon generator or these city maps or generated audio or face generators or buildings and patterns

On the topic of flowers there’s another actual implementation of the above mentioned concept available:

a proper 7-segment / 14-segment font

DSEG is a free font family, which imitate seven and fourteen segment display(7SEG,14SEG). DSEG have special features:

  • DSEG includes the roman-alphabet and symbol glyphs.
  • More than 50 types are available.
  • True type font(*.ttf) and Web Open Type File Format (*.woff, *.woff2) are in a package.
  • DSEG is licensed under the SIL Open Font License 1.1.

Get it here.

dangerously curious bitcoins

Some things you find on GitHub are more interesting and frightening than others.

This one is both and some more. What is it you ask?

R2 Bitcoin Arbitrager is an automatic arbitrage trading application targeting Bitcoin exchanges.

So it’s buying and selling Bitcoins. And it’s doing this on different markets.
On the topic of arbitrage Wikipedia has something to say:

In economics and finance, arbitrage is the practice of taking advantage of a price difference between two or more markets: striking a combination of matching deals that capitalize upon the imbalance, the profit being the difference between the market prices at which the unit is traded.

For example, an arbitrage opportunity is present when there is the opportunity to instantaneously buy something for a low price and sell it for a higher price.

Now this already is the second version of the tool and already 2 years old. See it as some sort of interesting archeological specimem. Please refrain to actually so something harmful with it.

I am writing this down here because apart from it’s obvious horrors this is a good starting point to understand how these computer-trading-systems do work in principle.

Given that an architectural drawing is also included it gives all sorts of starting points to thoughts.

Also. What could possibly go wrong if a tool to buy/sell on actual markets with actual bitcoins is confident enough to include the “maxTargetProfit” configuration option. Effectively setting the top-line of profit you’re going to make!!!111

Linux mac80211 compatible full-stack Wi-Fi design based on SDR

In a tweet we were given an early christmas present – open-sdr released an open source software Wi-Fi stack that utilizes software-defined-radio technology to implement actual working Wi-Fi.


  • 802.11a/g; 802.11n MCS 0~7; 20MHz
  • Mode tested: Ad-hoc; Station; AP
  • DCF (CSMA/CA) low MAC layer in FPGA
  • Configurable channel access priority parameters:
    • duration of RTS/CTS, CTS-to-self
    • SIFS/DIFS/xIFS/slot-time/CW/etc
  • Time slicing based on MAC address
  • Easy to change bandwidth and frequency:
    • 2MHz for 802.11ah in sub-GHz
    • 10MHz for 802.11p/vehicle in 5.9GHz
  • On roadmap: 802.11ax

See this demonstration:

OpenFood Facts

Open Food Facts gathers information and data on food products from around the world.

To replace MyFitnessPal in our toolchain I am on the hunt for at least some quality food fact data.

The Open Food Facts data base seems to be one source – although in sparse and questionable quality (after first initial testing).

There is a comprehensive documentation about the fields of data supported. And there are several formats that the raw data can be downloaded in.

There are ready-made applications available as well. Definitly worth looking into further.

smart OpenVPN client for iOS

There is a free and well integrated OpenVPN client for iOS devices already. And as much as this one works quite well it’s also lacking some comfort features that are now made available through alternative iOS client implementations of OpenVPN.

OpenVPN is an open-source commercial software that implements virtual private network techniques to create secure point-to-point or site-to-site connections in routed or bridged configurations and remote access facilities. It uses a custom security protocol that utilizes SSL/TLS for key exchange.

Meet Passepartout. The iOS OpenVPN client that comes with lots of comfort features. Of main interest for me is that Passepartout is aware of the connection you’re currently using and can adopt it’s VPN tunnel status accordingly.

Passepartout is a smart OpenVPN client perfectly integrated with the iOS platform. Passepartout is the only app you need for both well-known OpenVPN providers and your personal OpenVPN servers.

collection of pure bash alternatives to external processes

The goal of this book is to document commonly-known and lesser-known methods of doing various tasks using only built-in bash features. Using the snippets from this bible can help remove unneeded dependencies from scripts and in most cases make them faster. I came across these tips and discovered a few while developing neofetchpxltrm and other smaller projects.


eXoDOS is an attempt to catalog, obtain, and make playable every game developed for the DOS and PC Booter platform. Striving to find original media rather than using scene rips. This collection uses a combination of Dosbox and ScummVM to play these older titles on modern systems. All required emulators are included and have been setup to run all included titles with no prior knowledge or experience required on the users part.

This pack includes 7,000 DOS games. The focus is on games that were either released in English or are fairly easy to play without a knowledge of the native language. This is not every DOS game ever made, however it is a very high percentage of all commercial releases. There are thousands of freeware, homebrew, and shareware games that will continue to be added in future packs.

The games have already been configured to run in DosBOX. Games which are supported by ScummVM will give you the option at launch as to which emulator you would like to use.

the big list of RTL-SDR supported software

RTL-SDR is a very cheap ~$25 USB dongle that can be used as a computer based radio scanner for receiving live radio signals in your area (no internet required). Depending on the particular model it could receive frequencies from 500 kHz up to 1.75 GHz. Most software for the RTL-SDR is also community developed, and provided free of charge.

The origins of RTL-SDR stem from mass produced DVB-T TV tuner dongles that were based on the RTL2832U chipset. With the combined efforts of Antti Palosaari, Eric Fry and Osmocom (in particular Steve Markgraf) it was found that the raw I/Q data on the RTL2832U chipset could be accessed directly, which allowed the DVB-T TV tuner to be converted into a wideband software defined radio via a custom software driver developed by Steve Markgraf. If you’ve ever enjoyed the RTL-SDR project please consider donating to Osmocom via Open Collective as they are the ones who developed the drivers and brought RTL-SDR to life.

And since the hardware is so affordable there’s lots of software and therefore things that can be done with it.


Streamsheets is, similar to NodeRed, a tool to step in between MQTT data coming in and something being done with it. Just other than NodeRed it is not based on flows but on a spreadsheet that executes in it’s entirety everytime a step is made.

Streamsheets are a new spreadsheet technology specifically designed for real-time data stream processing and the opportunities of digitization and the Industrial IoT.


SwiftUI on the Web

SwiftUI is the new cool kid on the block when it comes to iOS/iPadOS/macOS application development.

As Apple announced SwiftUI early 2019 it’s naturally only focussing on making all the declarative UI goodness available for the Apple operating systems. No non-apple platforms in focus. Naturally.

But there are ways. With the declarative way of creating user interfaces one apparently can simply start to re-implement the UI controls and have them render as HTML / Javascript…

The SwiftWebUI project is aiming to do so:

Unlike some other efforts this doesn’t just render SwiftUI Views as HTML. It also sets up a connection between the browser and the code hosted in the Swift server, allowing for interaction – buttons, pickers, steppers, lists, navigation, you get it all!

In other words: SwiftWebUI is an implementation of (many but not all parts of) the SwiftUI API for the browser.

To repeat the Disclaimer: This is a toy project! Do not use for production. Use it to learn more about SwiftUI and its inner workings.


Making a RISC-V operating system using Rust

As RISC-V progressively challenges the existing ARM processor ecosystem it’s interesting to see more and more software projects popping up that aim that RISC-V architecture.

Here’s one project that aims to develop (and explain along the way) how to create an operating system from scratch. On top of the RISC-V specifics this tutorial also aims to teach how this all can be done in a programming language called Rust.

Keep in mind that all of this is done on a baremetal system. No other software is running.

RISC-V (“risk five”) and the Rust programming language both start with an R, so naturally they fit together. In this blog, we will write an operating system targeting the RISC-V architecture in Rust (mostly). If you have a sane development environment for RISC-V, you can skip the setup parts right to bootloading. Otherwise, it’ll be fairly difficult to get started.

This tutorial will progressively build an operating system from start to something that you can show your friends or parents — if they’re significantly young enough. Since I’m rather new at this I decided to make it a “feature” that each blog post will mature as time goes on. More details will be added and some will be clarified. I look forward to hearing from you!

The Adventures of OS

a 1980s style computer built today for fun

Can you display VGA and play audio on a Cortex-M4 in pure Rust? The short answer is yes, yes you can! Minus the hand-unrolled assembler loop for fixing the phase error in the RGB output. But we don’t talk about that in polite company.

Monotron project page

What currently is in place:

  • The Atari Joystick interface works, but two Joysticks would be more fun
  • The PS/2 Keyboard via the Atmega works, but the pinout was mirrored so you have to put the connector under the PCB :/
  • The RTC works
  • VGA Output works
  • The MIDI Out seems to work when looped to MIDI In, as does the MIDI Though.
  • The MIDI In seems to receive data when connected to my electronic drum kit
  • The Audio output seems to work quite nicely
  • The SD card works, but the power supply can’t handle hot-insertion of the SD card and it makes the TM4C reboot. More capacitors / some current limiting probably required.

I can load games and programs from the SD card into the 24 KiB of free Application RAM. You can interact with these games via the PS/2 Keyboard and Joystick. I can play simple games (like Snake) and play three channels of 8-bit wavetable audio simultaneously. I’ve even got a 6502 Emulator running a copy of 6502 Enhanced BASIC, if you want to go old school!

Localino – Indoor Location

As you might know I am regularly looking into indoor-location systems and opportunities to optimize my own system (based on Bluetooth…)

Now I cam across a concept by a german company called Localino. They’ve built their own hard- and software.

Localino has its own “satellites”, also called “anchors”. The mobile receivers are called “tags” and can locate their position based on the available anchors inside a building. Anchors and tags precisely measure signal propagation delays in the order of sub-nanoseconds, resulting in centimeter-accurate location. Any person or object wearing a tag can be located.

Localino website

There’s also a hack-a-day article on the system which states that all hard- and software would be open source. So far I did not find any source code though…

As far as I could dig into this so far it’s based upon decawave DW1000 hardware and an older base-library of this is available as source code here.

There are some other mentions which are back from 2017 when there seemingly was a big open source portion. Some python code is mentioned but nothing available right away today sadly.

REST-API testing: Reqres

I am back again and developing some smaller APIs for my own use.

As I am learning a new programming language and framework (SwiftUI) and for my little learning project I need to also implement a server backend. Implementing a RESTful service is quite straight-forward but for testing and UI prototyping I actually want to do some testing before really setting up the server side.

To easily test RESTful calls without actually implementing anything I found that Reqres is a quite useful tool to have in the toolbelt:

Apart from some pre-set-up API endpoints with dummy data (like users, …) it also features a request mirror service.

With that you can simply throw a JSON document into the general direction of Reqres and it will put a timestamp on it and return it right away.

Like so:

Writing Network Drivers in C#

Somebody had to do it. Maximilian Stadlmeier did:

User space network drivers on Linux are often used in production environments to improve the performance of network-heavy applications. However, their inner workings are not clear to most
programmers who use them. ixy aims to change this by providing a small educational user space network driver, which is gives a good overview of how these drivers work, using only 1000 lines of C code.
While the language C is a good common denominator, which many developers are familiar with, its syntax is often much more dicult to read than that of more modern languages and makes the driver seem more complex than it actually is.

For this thesis I created a C# version of ixy, named ixy.cs, which utilizes the more modern syntax and additional safety of the C# programming language in order to make user space network driver development even more accessible. The viability of C# for driver programming will be analyzed and its advantages and disadvantages will be discussed.

The actual implementation (with other programming languages as well) can be found here.

Apparently it’s not as slow as you might think:

Bulletin Board Systems in the wild

While recording a podcast episode we briefly touched on the topic of bulletin board systems and how we both had operated our own FidoNet BBS in the 90s.

To create a bigger reflux of thoughts:

Synchronet Bulletin Board System Software is a free software package that can turn your personal computer into your own custom online service supporting multiple simultaneous users with hierarchical message and file areas, multi-user chat, and the ever-popular BBS door games.

Everything there to set-up a BBS. Maybe I really need to get out a backup of my old BBS and bring it back online?!

One Soundcard to rule them all

The first sound card I got as an upgrade to a PC without sound back in 90s was the glorious Sound Blaster 16:

There were several different sound card options back in the days and all sounded a bit different.

sound card (also known as an audio card) is an internal expansion card that provides input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces used for professional audio applications.


With the synthesizers and audio processing each series and make produced a distinctive sound. Some of us want to bring these sounds back. But keeping the (old) hardware running is an increasingly difficult task.

For example: The interface used by the above mentioned Sound Blaster 16 card is the ISA bus interface. This interface was introduced in 1981 and replaced in 1993. If you want to hear how such a sound card sounds today you would have to run hardware from this time period.

But some people are working towards getting at least some authentic sound back.

In this talk, Alan Hightower takes a look at the complexities, challenges, and even current progress at integrating all of the above cores into one FPGA based ISA sound card.

This is what the concept would bring if done:

Oh that would be soooooo nice to have all these vintage sound interfaces available and to be able to actually use them for audio output.

using AI to generate human faces from emojis and thumbnails

Back in March 2019 we’d already seen artificial people. Yawn.

Back then a Generative adversarial network (GAN) was used to produce random human faces from scratch. It synthesized human faces out of randomness.

Now take it a step further and input actual small images. Like thumbnails or emojis or else.

And what do you get?

Quite impressive, eh? There’s more after the jump.

Oh and they wrote a paper about it: Progressive Face Super-Resolution via Attention to Facial Landmark

Magnificent app which corrects your previous console command

We all know this. You typed a loooong line of commands in your shell and you made one typo.

That’s the worst.

Now. There’s a command that aims to help:

It is rather simple. But extremely effective.

The Fuck attempts to match the previous command with a rule. If a match is found, a new command is created using the matched rule and executed.

Grab it on github. Install it right away. It went into my toolbelt in an instant.