Ayke van Laethem

Syncthing on a Kobo

Mon, 10 Aug 2026 00:00:00 +0000

How to install Syncthing on a Kobo e-reader

RGB LED earrings (36 LEDs, with microphone)

Wed, 10 Jun 2026 00:00:00 +0000

These are new earrings, very similar to my previous 36-LED earrings but with an extra button (to make it easier to cycle through many modes) and a microphone (for audio reactivity and programming custom patterns). Other than that, they're almost identical: same MCU, same LEDs, same PCB shape, etc.

You can find the KiCad design files, source code, and instructions on how to program them on the GitHub page.

I sell them on Lectronz!

Hot chocolate

Mon, 11 May 2026 00:00:00 +0000

Extra hot chocolate, with the addition of pepper.

Vegan pea soup

Mon, 11 May 2026 00:00:00 +0000

A variation on a traditional Dutch winter dish.

Binary Code Modulation

Thu, 15 Jan 2026 00:00:00 +0000

Bitbanging many LEDs from a microcontroller can be very fast, when using Binary Code Modulation and some assembly.

Charlieplexing

Wed, 14 Jan 2026 00:00:00 +0000

Charlieplexing is kinda difficult to wrap your head around initially, but once you understand it, it actually makes a lot of sense. This post will try to show you how it works and why it's actually quite beautiful.

RGB LED earrings (36 LEDs)

Tue, 09 Dec 2025 00:00:00 +0000

I've made new and improved RGB LED earrings, with double the LEDs compared to my previous LED earrings. They also have some other improvements: they're more power efficient and the LEDs just look a lot better.

You can find the KiCad design files, source code, and instructions on how to program them on the GitHub page.

I used to sell them on Lectronz but these are all sold out. See the v2 version which has been improved in many ways!

Autoplay video on an analog TV using a Raspberry Pi 3

Sun, 09 Mar 2025 00:00:00 +0000

How to configure a Raspberry Pi to auto-play videos from a USB stick, without needing any input. It's not yet entirely working as intended, but this is what I got working so far.

Travelling while being neurodivergent

Mon, 30 Dec 2024 00:00:00 +0000

Tips and tricks on how to survive and even enjoy travelling when you're neurodivergent.

RGB LED earrings

Wed, 18 Dec 2024 00:00:00 +0000

I've made RGB LED earrings, like these:

You can find all the instructions on how to program it on the GitHub page.

I made these initially because I wanted to wear them myself, but as it turns out they're quite popular. You can buy them on Lectronz.

The design is available on oshwlab.com if you want to build your own.

Making a silent lounge

Sat, 21 Sep 2024 00:00:00 +0000

Some thoughts on what would be nice to have in a silent lounge, especially at hacker events.

Fast antialiased polygon scanline rendering

Thu, 08 Feb 2024 00:00:00 +0000

This post describes a fast algorithm for rendering polygons on slow hardware, and gives an intuitive explanation as to how it works. The algorithm was originally based on the A-buffer algorithm but modified to work better on modern microcontrollers.

TinyGo Preview - how does it work?

Sun, 08 May 2022 23:04:16 +0000

I've updated play.tinygo.org to more accurately simulate hardware, and now also brought this feature to VS Code. But how does it work?

CGo improvements in TinyGo

Thu, 18 Nov 2021 15:32:27 +0000

CGo is faster in TinyGo, here's how that works.

What's the int type?

Fri, 25 Jun 2021 17:01:44 +0000

The int type is present in many programming languages, but their meaning varies. Unlike what many people think, it only indirectly related to pointer size or architecture word size.

Optimizing constant bitshifts on AVR

Wed, 24 Feb 2021 17:54:42 +0000

The AVR architecture does not natively support arbitrary bit shifts. Therefore, compilers will have to be creative to make shifts short and fast. This post explores how a compiler could emit such constant shifts inline.

Garbage collection in TinyGo

Thu, 24 Sep 2020 22:22:10 +0000

An explanation of how garbage collectors work including some pseudocode how a real GC could be implemented.

ESP32 and ESP8266 support in TinyGo

Tue, 22 Sep 2020 13:42:11 +0000

How ESP32/ESP8266 support got added to TinyGo, how we got there, and the current status of support.

Debug AVR programs using simavr and avr-gdb

Mon, 22 Jun 2020 21:03:44 +0000

Quick note to get started with debugging AVR programs in a simulator

What RGB and sRGB mean

Sun, 29 Dec 2019 16:42:06 +0000

What RGB really means, what sRGB and gamma are and how to correctly blend colors.

DMA on the SAMD21

Thu, 19 Sep 2019 13:05:40 +0000

How to configure DMA on the SAMD21, for example to use it with SPI.

How the TinyGo playground simulates hardware

Wed, 17 Jul 2019 20:45:33 +0000

The TinyGo playground simulates real hardware, including an e-paper display. How can it do such things? This post explains a bit about how the playground works to make this possible.

LLVM from a Go perspective

Sun, 28 Apr 2019 17:21:54 +0000

A high-level overview of LLVM IR, showing how two simple Go functions can be translated to IR.

Goroutines in TinyGo

Mon, 25 Feb 2019 13:07:57 +0000

TinyGo uses LLVM coroutines to implement goroutines. This post explains what coroutines are and how they're used to implement goroutines.

Interfaces in TinyGo

Sat, 08 Dec 2018 23:36:43 +0000

How TinyGo implements Go interfaces in a radically different way, avoiding most memory allocations and reducing code size.

Defer is complicated

Tue, 04 Dec 2018 13:01:50 +0000

The defer keyword in Go does much more than you might think, leading to performance issues in some cases. Why is this?

Code size optimization for microcontrollers

Fri, 27 Apr 2018 18:28:44 +0000

How to optimize code size for microcontrollers, including compiler options and lots of coding habits that produce smaller and often more efficient code.

Internals of the MBR in Nordic SoftDevices

Tue, 16 Jan 2018 00:08:52 +0000

Nordic BLE chips contain a proprietary SoftDevice implementing the BLE stack. In this post, I will explain how the MBR region works and how to write your own.

Using PvGrub2 on Debian

Mon, 04 Dec 2017 19:04:48 +0000

Using pvgrub2 on Debian is very easy, and there is a little bit of documentation on the 'net, but not enough to cover all needs. I had to do some workarounds to enable pvgrub2 with btrfs.

Enforced STARTTLS for SMTP

Tue, 03 Oct 2017 21:46:13 +0000

While STARTTLS has traditionally been very sensitive to downgrade attacks, there are now two protocols to fix this: DANE and MTA-STS. I will take a look at how they work and how they can be implemented on your own domain.

Understanding modern mail authentication systems: SPF, DKIM and DMARC

Thu, 17 Aug 2017 17:54:30 +0000

Explains how modern email authentication systems work together to protect the "from" header in email. This makes phishing detectable and spamming more difficult.

Uploading README.rst to PyPI

Sun, 23 Jul 2017 18:54:08 +0000

My experience with making a Python package and uploading it to PyPI. Sometimes, such systems aren't as sophisticated as one might expect.

Managing phone addiction

Sun, 25 Jun 2017 20:31:47 +0000

A few tips on how to track how much you're addicted to your phone and how you can manage it. I give a short overview of how habits work. Then I describe how you can track how much you use your phone and give a few tips on breaking a few of those habits.

Using Arduino on the "blue pill" STM32F103 boards

Tue, 06 Jun 2017 19:47:41 +0000

As I gave up on Rust (for now), I tried setting up the Arduino environment to work with the "blue pill" board. It turns out to be quite easy, although there were a few small issues with the setup. You'll still need a (cheap) SWD programmer, though.

Intro to Rust on the STM32

Sun, 04 Jun 2017 01:04:45 +0000

How to write a simple Rust program for the STM32 "blue pill" board that's sold on AliExpress and Ebay for about $2. It turns out to be not too difficult.

Using AddressSanitizer and Valgrind on Android recovery

Fri, 02 Jun 2017 00:09:56 +0000

How to use memory checking tools inside an Android recovery to detect things like buffer overflows. A recovery system like TWRP is quite different from a normal Android image, so the official guides apply only partially and it needs some manual work to make these tools work. Here's how I did it.

Flashing the HM-10 firmware on a JDY-08

Fri, 12 May 2017 20:38:14 +0000

Use CCLoader to flash the official HM-10 firmware on a cheap Chinese JDY-08 device. Unfortunately, the process doesn't result in a working device, but at least I got somewhere.

Using the JDY-08 module

Thu, 11 May 2017 00:00:24 +0000

A look at the JDY-08, a cheap BLE module found on the online Chinese markets. It works, but it turns out that it isn't really useful with the original firmware.

Concise version vectors

Mon, 10 Apr 2017 16:15:03 +0000

Concise version vectors is the algorithm behind DTSync. It is a distributed algorithm with low memory complexity, with barely any overhead of adding another replica.

DTSync: bidirectional directory synchronisation between any number of replicas

Fri, 07 Apr 2017 01:02:23 +0000

A new bidirectional synchronization tool like Unison that can synchronize many distributed replicas

Putting a Raspberry Pi 1 SD card into a Pi 3

Sun, 19 Mar 2017 03:34:37 +0000

How to move an installed SD card from a Pi 1 to a Pi 3, or make it possible to use them both. There are a few tricks to get the network running on both devices.

LED strip

Fri, 10 Mar 2017 00:00:00 +0000

I have made a LED strip based on the ATtiny85 / Digispark.

ATtiny85 based

Here's a video, though it looks much nicer in real-life:

What you'll need:

An ISP programmer, for example another Arduino (or leave out some features)
A string of 30 LEDs type WS2812
Two generic push buttons
Soldering gear
Source code

Bootloader

I prefer the LED strip with a new bootloader. Flashing your own version has several advantages:

Installing Debian on a Btrfs subvolume

Tue, 24 Nov 2015 12:01:55 +0000

How to install Debian on a Btrfs subvolume to easily make system snapshots.

Safely Embedding JSON in JavaScript

Fri, 10 Jul 2015 15:08:53 +0000

How do you embed JSON in JavaScript? The naive approach turns out to have a XSS and DoS vulnerability, but this is easily fixed with a simple filter.

Setting up HTTPS on nginx from start to finish

Tue, 19 May 2015 13:32:00 +0000

Turn a plain HTTP web site served with nginx into one with HTTPS and SPDY support. Includes StartSSL, Postfix and OCSP stapling.

South: stateless authenticated sessions for HTTP in Go

Wed, 28 Jan 2015 22:09:13 +0000

I have written a Go package for stateless authentication using HMAC. I believe this system is in practice just as secure as session IDs without having to store state on the server, making authentication a whole lot easier.

:link and :visited are mutually exclusive

Sat, 13 Dec 2014 00:54:34 +0000

I discovered that the CSS pseudo-classes :link and :visited are mutually exclusive. This in contrast to what may seem more logical, that is, that :link applies to all links.

Fix 'jumping scrollbar' issue using only CSS

Mon, 08 Sep 2014 22:52:23 +0000

I discovered a technique to prevent page jumping when navigating between short and long pages without showing the scroll bar all the time.