Mosquitto is a lightweight MQTT broker that is suitable for embedded use. It also provides built-in support to persist and store messages which can be used to implement reliable communication even when the network is not stable. This post describes how to set up the persistent storage, what are the main parameters to tune it and how to troubleshoot the setup. Continue reading “How to set up persistent storage for Mosquitto MQTT broker”
My car comes with a built-in Bluetooth hands-free but unfortunately it does not support audio streaming. Luckily there is an AUX input available which uses a regular 3,5 mm jack. Perfect opportunity for a DIY project. I built the Bluetooth DAC using Raspberry Pi Zero W and a DAC hat. This post depicts the details of this project. Continue reading “Building a Bluetooth DAC with Raspberry Pi Zero W”
Being able to verify that a piece of data originates from a trusted source (authenticity) and that it has not been altered in transit (integrity) is a common requirement in many use cases. It is needed for instance when distributing software packages and installers and when delivering firmware to an embedded device. Digital signatures allow the recipient to verify both authenticity and integrity of the received document. This blog post describes how to use digital signatures with OpenSSL in practice. First part describes what is a digital signature and then the second part shows how to use OpenSSL sign and verify functions to work with signatures.
Continue reading “How to sign and verify using OpenSSL”
Customized Linux distribution and a safe systems programming language sounds like a very interesting combination for embedded development. That is what makes Yocto and Rust such a good match. So, I wanted to see how Rust projects could be cross-compiled with Yocto-generated toolchain and root filesystem. The steps are described in this post. Continue reading “Embedded development with Yocto and Rust”
Sonoff S20 (specs) is a smart power outlet that is controllable with a WiFi connection. The device comes with a built-in firmware and an accompanied mobile app, but it is also possible to flash it with custom firmware. This allows to control the device with standard MQTT protocol making integration to DIY home automation or IoT cloud systems easier. This post provides a step-by-step guide how to flash the device and also examples how to interface with it using MQTT. Continue reading “How to flash Sonoff S20 WiFi outlet with Tasmota MQTT firmware”
After committing, I always like to go through the diff before pushing the changes upstream. Just to make sure that everything is as it should be. Well, quite often I still spot some typos, commented out code that I was supposed to remove or some other minor things that need to be fixed. So I ended up running the same exact commands time and time again. First new commit for the fixes and then interactive rebase to squash the changes to the previous commit. Perfect opportunity to make an alias to save those precious keystrokes. Continue reading “Git: easily auto-squash changes to previous commit”
Git-completion and git-prompt are scripts that provide versatile completion support as well as visualization of current branch and status when working from the command line. Even though I work with git daily I hadn’t bumped into these scripts until quite recently. They have proven to be very useful, so I decided to share this tip. Continue reading “Improved git CLI with git-completion and git-prompt”