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Reading my solar inverter over RS485

For over ten years, the only way I have had of knowing what our solar panels are doing has been an impulse monitor on the generation meter, counting the flashes of its LED. It has always been a bit flaky due to battery changes or loose connections, and there has never been a way to see solar generation alongside the energy used by the rest of the house. This week I have fixed that, by building a small ESPHome sensor which talks directly to the inverter. I am still reeling slightly: with AI assistance, it took under a week from idea to working implementation, and it is a project I would certainly never have attempted otherwise. The result is zeversolar-esphome. ...

October 10, 2026 · Tim Retout

TF RAID

My hobby: following GOV.UK to look for interesting announcements. Today was an update on the MOD’s Rapid AI Delivery Taskforce which was previously announced in June during London Tech Week. ...

August 25, 2026 · Tim Retout

Renewal relationships between AWS certifications

When you pass an AWS certification exam, sometimes it can extend the life of related lesser AWS certifications. But I could not find an illustration of exactly which ones, so here’s an up-to-date diagram: ...

July 20, 2026 · Tim Retout

Blocking distracting news links

“You are what you eat” – but perhaps this is even more true of our information diet. It is hard to strike a balance between remaining a well-informed citizen versus spending hours ingesting unnecessary news about issues and events we can’t affect. But I’m increasingly convinced that my hours lost to doomscrolling are down to design choices by web publishers rather than a failure of individual willpower. ...

July 10, 2026 · Tim Retout

AWS Washington Summit 2026

I am somewhat jet-lagged, having returned from Washington DC just before the 250th anniversary celebrations which will be happening today. I was part of a delegation sent by my employer to the AWS Summit there this week, partly to kindle interactions between PA Consulting and Jacobs who have recently taken a 100% share in PA. ...

July 4, 2026 · Tim Retout

seL4 repo relationships

The seL4 organisation on GitHub uses git-repo to manage multiple source repositories, and so there are a large number of projects to get your head around when figuring out the ecosystem. As an experiment, I have taken the various manifest files across the org, and constructed a graph based on how frequently each pair of repositories is mentioned in a manifest together. See below: ...

June 21, 2026 · Tim Retout

In memoriam commit-email.py

I have proposed the deletion of an obsolete script, but it makes me feel complicated feelings so I’m going to try and express those. This particular script was written in 2014, but the concept goes back much further – before git was invented. ...

June 15, 2026 · Tim Retout

seL4 clock magic

I have been looking at seL4 some more recently, and had a small patch merged today to remove a legacy Python module from a helper script. (I was trying to run the script on a system without that module installed, and it was almost easier to patch it out.) However, the more I think about this code and how it’s used, the more it seems wrong on at least five other levels. ...

June 12, 2026 · Tim Retout

Strauss as Pop Music

While watching the Vienna New Year’s Concert today, reading about its perhaps somewhat problematic origins, I was struck by the observation that the Strauss family’s polkas were seen as pop music during their lifetime, not as serious as proper classical composers, and so it took some time before the Vienna Philharmonic would actually play their work. (Perhaps the space-themed interval today and the ballet dancers pretending to be a steam train were a continuation of the true spirit of this? It felt very Eurovision.) ...

January 1, 2025 · Tim Retout

seL4 Microkit Tutorial

Recently I revisited my previous interest in seL4 - a fast, highly assured operating system microkernel for building secure systems. The seL4 Microkit tutorial uses a simple Wordle game example to teach the basics of seL4 Microkit (formerly known as the seL4 Core Platform), which is a framework for creating static embedded systems on top of the seL4 microkernel. Microkit is also at the core of LionsOS, a new project to make seL4 accessible to a wider audience. ...

April 29, 2024 · Tim Retout