I think cost is a critical consideration which has not been mentioned yet.
For PnP, I think support for all OEM features is desirable, and additional features could be put over CAN or perhaps some kind of RJ45 Ethernet. AKA if your adding wires to you PnP, why would it need to go into the existing harness connector(s)? Also if you add wires, why not use OEM connectors which are likely to have a long life like RJ45 or the industrial M12? They are robust, low cost, weather resistant, etc.
I understand the desire to make a modular PnP board, but I also see negative trades for trying to keep it flexible. The point of PnP is to trade flexibility to get simpler easier to install hardware. It's all about instant gratification. As well a goal of flexible is to keep development costs low. If you can re-spin just one section, you don't have to purchase an entire PCB. That's handy to keep the costs lower as you find bugs. However you're adding labor to every build when you do that. The PnP crowd doesn't want this labor. They are willing to pay an extra couple bucks to avoid this labor.
I agree with Knock in software. I once had a circuit on the o5e board. Hmmm, I think the o5e has fallen victim to bit rot. I couldn't find it in my 1 minute search. If someone created an excel spread sheet which showed the DSP algorithm to @
, I'd bet he'd make such an option in software. Right now I think the key reason it has not happened is because @
needs to know how it would work at a very detailed level. I think a spread sheet would be a great way to show exactly how that would work.
I also agree VR with an op-amp instead of the MAX chip is a good goal. The Max chip is expensive and proprietary. We could make something and remove the magic. My concern is that PCB real estate will increase if we roll our own. As well we have a solution, so this is kind of re-inventing the wheel on a project that is already a re-invention of the wheel. While I find it interesting and I desire to learn the low levels, the end users don't really care. They don't really care if they toss an extra $5 and use the MAX chip. However I want to know exactly what is happening under the hood.
I think the modular design in PnP shouldn't be to allow people to solder in different modules, but to allow for a modular PCB designs. Similar to what we tried in Frankenstein. We did a layout where we could change sections. I think PnP should be an assembled by an assembly house, then validated by someone with some kind of test fixture. Then a user snaps it in. Decreasing the assembly house labor is critical in keeping the costs low. If a chip goes obsolete, then you will need to do a re-design of the board. Hopefully you can simply re-do that one section of the board. The goal of modular PCB is to keep labor down. There is upfront NRE in spinning a board, as well as repetitive labor costs. I think there are benefits of moving the modular level to the one time development costs and avoid that kind of labor to the every build level.
ASIC's can be lower cost than one might think. I understand it's common for Universities to do a batch run of ASIC's, similar to how PCB's are batched at OSHPark. If you can find a group which is running a custom batch of ASIC's that can reduce the ASIC costs allot. I understand many foundries also provide generic libraries for things like MOSFET's, and other similar interfacing circuits. It would be cool to run our own ASIC. I'd enjoy doing such a effort.
About what the next rusEFI hardware will look like, that really depends on the PCB developers motivation. With free labor, it's what ever the developer feels like doing. Also it helps when a developer has the hardware. I've developed Frankenso, and I don't have a Miata, or any thing close. Some day I dream of fixing up an old motorcycle. So some day I might get motivated to make a motorcycle ECU. As well my daily driver(s) are FSI 2.0 VW engines. So I might get motivated to do that, if I desired that making it to work is a lower priority goal
About a PnP effort, I might suggest using the priority chips for things like fuel injectors, and power supplies. That would make the PCB modules get really small. Then once you have the core modules small, then put it on a PCB edge which matches an existing enclosure, and matches an existing ECU connector. If you change to another ECU, then change the PCB edge cuts and change the ECU connector, but keep the core modules.