Oh, don't get me started on what the problem is :D
* Espresso machine electronics are very proprietary. There's basically one manufacturer, no published schematics and very closed firmwares.
* That one manufacturer's hardware occasionally breaks and needs replacement, and they charge up the wazoo for it.
* Firmware updates is not a thing. Buying a new controller with the new firmware is your only option.
* Espresso machine electronics hardware is pretty firmly stuck in the past. If you're lucky you have a 128x64 px OLED, but more likely you have LED indicators, 7 segment displays, or graphical LCDs.
There are absolutely exceptions to this, but for 95% of the espresso machines out there, you're definitely not getting the full potential of the hardware.
> * Espresso machine electronics hardware is pretty firmly stuck in the past. If you're lucky you have a 128x64 px OLED, but more likely you have LED indicators, 7 segment displays, or graphical LCDs.
I don't know if I'd consider adding a screen to an espresso machine to be an improvement. What would it be useful for?
I have a no-display machine and I wish it had a few things that a screen would facilitate:
(1) Automatic shot timer.
(2) Shot volume display (my machine is a volumetric one, but I have to measure the weight of the output to calculate what volume it dispensed)
(3) Ability to configure other parameters, such as pre-infusion time, where I'm guessing the manufacturer just left this out because it would complicate an already kind of painful button + LED UI.
I also wish it had a group head temperature sensor, but that would add more hardware to the machine than just the screen.
I don't think any of these issues are solved by selling you a pile of parts and having you build the machine yourself. An open/more flexible PID is a great idea, but that's just one piece of this product & could be built into an already assembled machine. There are some machines (Decent, Sam Remo You) that give you a lot more control, but even this level of control probably goes unused by a lot of its users if the h-b forums are to be believed.
More control than that, or a totally open PID, might be a hard sell for safety reasons. That alone is a nonstarter, but even as you approach that level of openness, it would be pretty hard to support and really isn't needed if you just want a good shot of espresso and aren't taking an niche academic approach to an already niche process. This is why you likely won't see it in more commercial machines.
Perhaps you're thinking of the commercial market and I'm thinking of consumer, but there's been a lot of really interesting developments in the last few years at the intersection of affordable and high quality output -- I own a plus Bambino plus now, for example, which is simply a delightful machine, though I too wish I could modify the firmware.
Gicar. If you're looking at home machines from manufacturers that also do commercial (e.g. Profitec, ECM, Lelit, Rancilio, La Marzocco etc), they almost exclusively use Gicar electronics.
* Espresso machine electronics are very proprietary. There's basically one manufacturer, no published schematics and very closed firmwares.
* That one manufacturer's hardware occasionally breaks and needs replacement, and they charge up the wazoo for it.
* Firmware updates is not a thing. Buying a new controller with the new firmware is your only option.
* Espresso machine electronics hardware is pretty firmly stuck in the past. If you're lucky you have a 128x64 px OLED, but more likely you have LED indicators, 7 segment displays, or graphical LCDs.
There are absolutely exceptions to this, but for 95% of the espresso machines out there, you're definitely not getting the full potential of the hardware.