Puma board for FreeEMS

[Fred]

Actually, the argument about digiprotect on the rpm in is moot anyway as it needs XOR in there for selection of polarity of signal, and that will make an excellent buffer.

Additionally, the load/run switch pin should be hooked to a buffer and LED and header out, this will be the CEL pin, it's marked as "tach out" at the moment, but I think this makes more sense and will give us another means of diagnosis on board.

If you use a second identical xor chip like the other, there will be a spare pin on it for some other buffer. As far as digital outputs outside the case go, I'd very much like to see xor or line driver buffers in place to provide some current capability, otherwise anyone that wnats to do anything will need to provide a buffer of their own. Just a thought, and its up to the designer, marcos, how he does that, as long as the pins are protected. This is just my preference. The input polarity stuff is important, though, if the board is going to be marketed to different people with differnet sensor config. If the max chip supports inverting its output, then no problem, otherwise we need that for various inputs, I think. Or not? Shlt, I can't remember now. One thing is for sure, the code will not have input polarity configuration on it.

Fred.

[jharvey]

I have a first draft of this connector document drafted and checked into git. See here for an xls copy.

https://github.com/jharvey/puma_JAH/blo ... inouts.xls

I also created a cvs copy of it, such that it can viewed with a simple text editor. That's found here.

https://github.com/jharvey/puma_JAH/blo ... inouts.csv

I plan to iron a bit more out on it, but I ran out of time for the moment.

[jharvey]

I just made some models and drawing for the MAP footprints. I did that for both AAP and MAP bodies, as well as the others we aren't currently using like the stove pipe style, and both SMT styles. This should help with the MAP clearance issues, and I can now move into making/updating the footprints. However I ran out of time again. So I pushed the model files to git.

[jharvey]

I seem to recall there was an issue with the MAP's interfering with each other. I just updated the footprint, and I'm not seeing the issue. See below pictures.





Can I get more data about this MAP issue? Do my models look similar to what we really have?

[Fred]

OK, I see the intent now, and your (collective) mistake, but it's not *really* good enough. The AAP sensor should have a hose barb too such that it can be referenced to an appropriate part of the vehicle, not the interior cabin pressure (if desired). Try again with two of the ones with mounting feet ;-)

Also, they need somewhere to mount! They aren't close enough (1.5 or 2mm shy) to the edge to mount on a piece of flat alloy that comes right past there, and they stick up WAY high compared to the case. You can't fold them over onto the PCB either as that would cover the header location. I think it would be *MUCH* better to have the SMD style of barbed sensor on the board if they can be accommodated.

Ahhh, I see the issue with your rendered pic, you have them in backwards, or your case model to pin numbering is backwards. If I installed it wrongly into the holes it would indeed be the right distance from the edge, but it would still stick up what I consider a lot, OK, actually looking again, they stick up the same as the to220 parts, so it's fine if you move them 1.5 or 2mm closer to the edge. I can be more exact later.

As for the second sensor fowling the first, there is pcb room to move it further to the end and clear, so we should, which wont cause any downsides for anything else (that i can see) and will provide more options to users.

Awesome work on the models! :-) Are you upstreaming work like that back to kicad? You should :-)

Thanks for the CSV, I will check it out after breakfast and have a play while installing my resistors again... (THANKS Jean!)

Fred.

[Fred]

Also, I'm not sure if this has been noted on the list or on the forum yet, BUT, I realised the other day when chatting to Marcos that he has put 12v feeds for everything on the board, this is totally wrong and pointless and harmful to performance, so when they are removed there will be a lot more PCB space available. 12v is fed to the injectors, coils, relays, etc directly from fused wiring loom. Not through the EMS box. The EMS box purely grounds those devices. Just noting it here for reference.

Fred.

[Fred]

re the load/run switch and CEL, if it is connected up correctly, it can serve two functions, A when code is running as a CEL, B which position the SM switch is in. I might make some preliminary mods to mine to do just that in the short term.

Fred.

[Fred]

OK, I did a bit of doc work for the project:



This is almost certainly the format that I would want if simply trying to hook stuff up.

Jared, can you check my work, I think it's correct if your csv was. One thing is missing, though, the GP ADC, which pin is that? It should be included on the above also. Ditto the K+/K- should have (ADC1-0) or something near them.

Using my image, I will attempt some testing later. Thanks for the CSV :-)

Fred.

[Fred]

Now that the picture is complete, and I know that all of the grounds are CPU grounds (I think we should stop calling them analogue, as it's the cpu that we care about the ground point of, for all digital and analogue readings, etc) I really like the layout. Everything that needs a ground has one close by, nice.

[jharvey]

OK, I see the intent now, and your (collective) mistake, but it's not *really* good enough. The AAP sensor should have a hose barb too such that it can be referenced to an appropriate part of the vehicle, not the interior cabin pressure (if desired). Try again with two of the ones with mounting feet

The MPX4250A only offers the barb straight up, or SMT. The SMT is often considered to weak for direct mount, so you have to add a barb in your box, such that you don't accentually pull the SMT part off by tugging the hose. However, more fittings means more places for failure. Perhaps what I did with MultiMAP might be a good alternative solution.



Are you using the 250, or the 100? The 100 offers more packaging options. I agree we should space them out to allow for two that have the thru hold mounting option. Or perhaps either SMT or the barb. We'll have to look at this closer.

Also, they need somewhere to mount! They aren't close enough (1.5 or 2mm shy) to the edge to mount on a piece of flat alloy that comes right past there,

Hmmm, I wonder if we could be having a first vs third angle projection issue. Here in the states the default is as you would expect, exactly the opposite of everyone else. We use third, while most use first. The datasheet doesn't specify what projection it is, my model assumed Freescale would follow American standards. This looked right to me, as it landed just about perfect on the edge of the board, so it would appear Marcos thought the same. Pin 1 is identified with a notch, I just verified with some pictures I had laying around and yup the datasheet shows it backwards from how I expected. I'll update the model, and we'll move them closer to the edge.

Awesome work on the models! Are you upstreaming work like that back to kicad? You should

I don't know where upstream is? They are in github, so if you know upstream, feel free to let them know it exists.

Thanks for the CSV,

Don't take it for granted, I did that quick, and didn't check it as through as I would like. But it's a drafted start.