This post was originally send out to my newsletter subscribers. The newsletter documents all my updates and imrpovements to the Lego Sorting bot. It is an almost monthly newsletter (in practice, I send out about 6 newsletters per year). You can read previous editions here, or you can subscribe using the form below.
Hello builders and makers,
Welcome to this (sort-of) monthly newsletter! You’re receiving this because you signed up for updates on the automated Lego sorting machine. If you’re no longer interested, feel free to unsubscribe using the link at the bottom—no tricks, no hard feelings.
Pushing Boulders
In Greek mythology, Sisyphus was cursed to roll a boulder up a hill for eternity. Every time he got close to the top, the boulder rolled back down. Software development sometimes feels just like that: solve one problem, and three new ones appear.
Let me tell you the story of my pursuit to redesign the LEGO sorting machine with cheaper, more accessible components.
Attempt 1: The Build HAT Dream
I started as a firm believer in the Build HAT. It eliminated the need for an extra hub, making the system simpler and cheaper. But the standard library was limited and unreliable, and writing custom firmware was beyond my capabilities. After too much time spent chasing ghosts, I made the difficult decision to scrap the idea.
Attempt 2: The PyBricks Broadcast Protocol
Next, I turned to the Technic Hub and the PyBricks library. PyBricks offers a few options for inter-device communication. The interesting ones are:
- A Bluetooth broadcast protocol that requires no setup at all.
- Bluetooth serial communication requires establishing a Bluetooth connection.
The broadcast protocol seemed simple and easy to use. What could go wrong? Implementing the protocol on the computer side was a nightmare. Someone had cracked it for Linux, but hadn’t ported it to other systems. I tried to write a Windows version, but abandoned ship before diving into the great technical depths of Bluetooth specs and low-level drivers.
Attempt 3: Serial Bluetooth (Revisited)
Third time’s the charm? I circled back to serial Bluetooth, which I’d previously dismissed as unreliable. But this time, it just worked. Maybe PyBricks improved, maybe the Bluetooth library did, or maybe the Technic Hub had a change of heart. Whatever the reason, the only hiccup was buffering the data (the hub sends it in tiny 10-byte chunks). That is a small price to pay for progress.
The Payoff: Plans and Code
Remember my promises from the last newsletter? They’re here.
- Turntable plans are now on Rebrickable—minimal parts, easy to adapt if you’re missing a brick or two.
- Software is up on my Codeberg profile.
The catch? No price tag, it’s all free. Documentation is sparse for now, but I’m working on a video tutorial. I didn’t want to delay the release any longer.
What’s Next?
As I near the top of this hill, I can’t shake the Sisyphus vibe. Will the boulder roll back? To hedge my bets, I’ve kept things simple. I very carefully tried to avoid overengineering the solution (a personal weakness).
For my end-of-year project, I’m going wild: experimenting with shaker-based sorting, inspired by other builders. Can I make it work with a pure LEGO build? No idea. But that’s the fun part.
As always, your feedback is absolutely welcome. Thanks for following along on this journey. Happy sorting, and I look forward to sharing more updates soon!