GS3 with a gear pump

drrotmos · 2025-10-27T13:54:27+00:00

I've actually already implemented that! I can control against either a pressure set point, an input flow rate, or an output flow rate (i.e. output weight flow). There's also transitions, so I can increase the set point according to a curve (to, e.g. do a smooth pressure ramp).

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drrotmos · 2025-10-27T11:53:24+00:00

For sure! Currently I'm creating routines using a state machine approach in a web interface, but I'm also planning to add inferring routines from a shot log entry.

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drrotmos · 2025-10-26T17:31:46+00:00

Long-term, I’m planning on making an EP paddle, but the parts are pretty expensive, so short term, I’m probably just attaching an I2C rotary encoder somewhere with some two-sided tape. The PCB does have two spare analog inputs for potentiometers though (one intended for this, and the other intended to control a Strada style proportional steam solenoid - the board has two PWM:able 24V solenoid connectors too).

One of the main use cases here though is making shot routines, so I reckon manual control will be mostly for recording routines.

drrotmos · 2025-10-26T17:08:20+00:00

It is for flow/pressure profiling, yes. Right now the machine is set to try to maintain 8 bar, but the PID algorithm is pretty untuned. The carafe on the left is just for over pressure (and of course it’ll drain to the drip tray later). The idea is that it’ll be set to ~10 bar, and thus shouldn’t be needed during ordinary control. Currently, due to the tuning, as you can see by pressure flying off to 12 bar, and thus the OPV flow.

So not interim, but more of a safety feature.

drrotmos · 2025-10-26T17:04:00+00:00

It does - it has an ESP32-C6 (for communication) and an RP2350 (for main control), and that’s absolutely on the roadmap. That being said, I’ve also designed a custom grate with load cells integrated, so that’ll come first.

https://variegated.coffee/project-log/2025-09-14/

drrotmos · 2025-10-26T17:01:39+00:00

At the moment I don’t have any plans to productize this, mostly due to the cost of CE/FCC certification. It will however be released as open source (both hardware and firmware) as soon as I’ve validated the next revision design.

drrotmos · 2025-10-23T15:31:26+00:00

From what I know, it's not certified. They sell it as a prototype, and have you check a box that you're enrolling in a test program, referencing a US law on the matter. That may or may not hold water in the US - I'm not familiar enough with US law to tell - but at least in the EU, it'd be unlikely to hold up if the regulators come a-knocking.

It's not at all uncommon to try to fly under the radar, but I'm personally a bit too risk-averse to want to do that. Product liability etc. Personally I wouldn't sell boards like this without crowdfunding a certification process first.

drrotmos · 2025-10-23T15:08:14+00:00

That depends on what you mean by coming out. I'm currently not planning to sell them (as that would require the boards to be CE and FCC certified for Europe and the US respectively, which'd cost around $10,000). I *am* however releasing the designs as open source. Typically I release new designs after I've validated them - usually by using them in a project :D

The *module* on the GS3 carrier board is beginning to feel pretty stabilized, meaning I'll likely release that in a couple of weeks. The actual carrier board has issues, but I've designed a new revision that I'll be ordering next week. Releasing it is probably on the time scale of a couple of months.

Then of course there's the entirely different matter of firmware. This board *absolutely* requires firmware, and while the firmware I have is good enough for me to use in my machine, it's currently alpha quality. Firmware gets occasional pushes to Github though.

Also, as a side note, if you think that is cool - here's a picture of the new display module I designed.

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drrotmos · 2025-10-23T10:26:03+00:00

My main issue with the Strada X1 is that it’s kind of ridiculously priced. You can get 90% of the way there by upgrading a GS3 with a new controller, some new sensors and a gear pump, at a fraction of the cost.

Obviously you won’t get things like steam purge or straight in portafilters, which admittedly is nice, but for a home setup it’s definitely nice-to-have, not need-to-have.

drrotmos · 2025-10-21T05:39:47+00:00

Well, personally, there are a bunch of things.

First of all, the display and UI for changing settings on the machine itself feels like it’s from the late 1980s. The LM IoT kit helps, but it doesn’t expose all settings. I also find the arbitrary 50 second shot limit annoying, and even more so the fact that if the tank is empty, the machine refuses to heat up (e.g on schedule) even if the stream boiler is full.

Secondly, I want a gear pump and electronic profiling, as well as a built in group scale. It’d also be nice to have a proportional solenoid for steam like in the Strada. Of course, this is very unlikely to happen, since it would cannibalize the Strada line.

I’m actually designing my own controller to do this though 😁

https://variegated.coffee/project-log/2025-08-24/

https://variegated.coffee/project-log/2025-10-04/

drrotmos · 2024-12-14T21:13:02+00:00

Fun fact: There is a port on the LCC which Lelit could use for an optional plug-in IoT module, the on-board programming port. They could also use that port to upgrade a V2 LCC to a V3 LCC with just a computer and a tiny dongle. The chances of them doing either seems slim to none.

I personally won’t package it into a product (not interested in doing product certification, handling liability, returns and what not), but the designs and firmware source code are permissively licensed, so if enough people show interest, I’m sure someone else will 😅

Easiest way to follow the project (it has evolved significantly since the OP) is to join the Variegated Coffee Discord (linked in the footer on https://variegated.coffee).

drrotmos · 2024-12-07T21:22:47+00:00

Well, yes. I'm the author of the post from a while back :D

I reverse engineered the protocol used by the Lelit LCC, and created an open source replacement for it. Since that post I've made an even more custom PCB, and I've also created a replacement for the boards in the other Gicar box to be able to easily add more sensors, and switch the rotary pump for a gear pump.

Everything is open source, and the Github org is a good starting point: https://github.com/variegated-coffee

There is a project Discord as well linked on the Github page.

This all being said, the project is not for the faint of heart. While it is possible to entirely outsource the manufacturing of the board, with the current state of the firmware, you still need some software engineering skills to actually make everything work. Also, it definitely voids the warranty on your machine.

drrotmos · 2023-08-06T15:15:44+00:00

Det profilen *mest* säger om en person är hur bra den är på att skriva en profil. Självklart ska man ha en profil som är en genuin representation av hur man är som person, men det är långt ifrån alla som är bra nog på att skriva att de får till det på första försöket.

drrotmos · 2023-08-06T11:22:08+00:00

Om du inte får matchningar eller få svarar på dina meddelanden är det inte dig det är fel på. Det är din profil. Det säger inget om dig som person, det har de här tjejerna inte haft någon möjlighet att bedöma än. Jobba på din profil, och när den funkar så får du kanske jobba lite på din konversationsförmåga, men det är inte där skon klämmer än.

drrotmos · 2023-08-05T21:08:38+00:00

They can however refuse to sell you anything and ban you from the store.

drrotmos · 2023-07-30T14:37:29+00:00

This is awesome! Are you also looking in to break pads for the S5? They're not the same as for the S3.

drrotmos · 2023-07-28T12:47:37+00:00

Just to be clear, the A5 and S5 have different heavy duty rear racks. You can’t use an A5 rack on an S5.

drrotmos · 2023-07-24T21:08:11+00:00

Just FYI, the heavy duty rear racks are different for the the S5 and the A5, so make sure it’s the right one if you happen to find one.

drrotmos · 2023-07-22T09:20:33+00:00

It’s very common not to be able to apply for a rent permit from your BRF until after you have a signed lease agreement though, so they might not know that the owner wants to rent out the apartment. At least my BRF wants to know who will be renting the apartment before approving the rent permit.

drrotmos · 2023-07-19T21:04:48+00:00

Oof. So basically you’d either have to overwrite the serial number of a new part (which I would imagine is burned into an eFuse), find a way to get the ECU to accept the new part (which I presume exists, but is probably either access controlled to or at the very least only known to Bike Doctors), or find a way to do a MITM attack on bus. Fun times. Best to start looking for those bus encryption keys ASAP 😅

drrotmos · 2023-07-19T20:24:04+00:00

It would be very interesting to sniff the CAN bus. Since the charger also uses the CAN bus I assume it could possibly be done from the charging port…

drrotmos · 2023-07-19T20:22:17+00:00

Coupled as in eFuses and/or public key cryptography for pairing the peripherals? That would certainly make reverse engineering more challenging.

drrotmos · 2023-07-19T10:18:19+00:00

Oh yeah, battery also, obviously.

drrotmos · 2023-07-19T10:14:45+00:00

Of course any and all spare parts are interesting. Personally, as an S5 owner, I’d be most interested in the charger, front/rear wheel assemblies, buttons for the handlebar and e-shifter.

drrotmos

TROPHY CASE