A nephelyte's approach to EMS

All home-built FreeEMS implementations without a forum of their own, usually TA-based.
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wraith
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A nephelyte's approach to EMS

Post by wraith »

Greetings all-

I probably wouldn't have written this, but Fred's sticky does imply that if you want to play with FreeEms, you should have a plan. So here goes.

First up, I know nothing about software design, and very little about hardware. I know something about EMS, mostly because of Megasquirt. I don't think that should hold anyone back, though..

I'm planning on making an EMS based mostly off of the Ravage schematics that are getting around. I'm planning to do it in a board stack, something like this-

Base board- Input connector (probably Nippondenso to suit the Toyota stuff I have), power supply, all the high current (and high R/F?) stuff like coil drivers, injector drives etc. I'm not entirely sure what all would belong here, but for me, this board would be usable in all configs, so 12 spark and 12 injectors, etc.

Next in stack, input board- things like VR conditioners, MAP, TPS, etc etc. I'd be doing everything I can to isolate these inputs from the base board, just bring in the power cleanly, somehow. Eventually the CPU would mount directly onto this board, I think. but for now, this would also have an 80+ pin header for..

The CPU board! I've got plans to build something nice and simple for the Freescale processor, but while the code for FreeEMS is still being worked on, I'd probably build a board that will run that other Freescale chip, along with that other code, purely for R&D and to see if it works ok, and hopefully not get my arse sued off. I like this idea, as it means I could probably swap processors in a couple of minutes, meaning I could maybe even provide feedback and stuff for the FreeEMS code! Kind of like Fred's idea of the FreeMS2, but with a decent baseboard.

I'm hoping to do all this on 100mmx100mm, double layer, through hole PCB from somewhere like ITEAD. This keeps my cost down and means it's easy to send boards to more intelligent people to do stuff with.

That's my roadmap. I may be completely off my tree, so if I am tell me. I don't know a lot, but brute force, ignorance and persistence got my ancestors this far, and I won't let them down!

Cheers
Ash
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Fred
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Re: A nephelyte's approach to EMS

Post by Fred »

It's just that if you go off trying to do it by yourself without voicing your plan, you'll get lots of stuff wrong, run into unnecessary issues and traps, get frustrated and pissed off, and likely fail. I don't want that outcome. Hopefully you've read this: viewtopic.php?f=41&t=1699 if not, do.

First thing, you're absolutely crazy if you try to drive your coils directly from the ECU. OEMs rarely do this, nor should you. If you do, your circuit and connectors and loom must be *perfect* or you'll have trouble. Just use OEM ignitors and drive them with a sufficient strength signal for them to operate properly. If you want to build your own ignitor, fine, but put it in the engine bay directly between coils and battery, where it belongs. This would have been fail number one ;-)

Secondly, 12 + 12 + powersupply + spare outputs on 100x100 = ambitious, at best. Build something for YOUR application, whatever that is. Your next one will look different/be better anyway. And see this: viewtopic.php?f=54&t=1084 Perhaps fail number two? :-)

Thirdly, as much as I have 1000 posts (likely literally) saying I love stacked designs, they're impractical and dangerous in the real world and prone to failure and problems due to the extra connections and ground/power routing difficulties. Could this have been fail three? :-)

CPU board, depending on which *other* board you mean, you may have some problems cloning it. However it doesn't bother me what you get up to, provided you don't distribute it here and implicate me. Being worked on is one thing, but it's very usable now. For example:


Image




LOL @ ancestors humour :-)

You forgot one minor/huge detail: Your application/engine/car. This is pretty key. Maybe a users' rides thread would bring all the boys to the yard? Everyone likes perving at pics of cars.

And the above is why I say "post your plan", I hope it makes some sense.

Fred.
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Re: A nephelyte's approach to EMS

Post by wraith »

Wow, thanks for the fast response, Fred! Great feedback!

Fail one- agree completely. I guess by 'driver' I meant, something that will drive LS2 coils. Bad terminology? Hopefully that will give me enough space to fix dramas with fail two..

Fail two- Agree. 4x4 lays out nicely, but I hadn't really thought through what a prick it might be to triple it. Don't get many V12s in WA anyway, I'll drop it to 8x8 and see how it designs. As far as the threads go, I've got every faith in your amazing ability to write code, and this is in anticipation of 0.4.0!

Fail three- Can't really comment, as I have very little idea when it comes to electronics. In a former life, I worked as a service tech on industrial printers, and they almost exclusively had a stack design. I have a feeling you are right- that said, I'm going to bang my head against the wall on this one, and see if I can make it work. I guess my justification here is that M$3X works OK with a tertiary board on a ribbon to a tertiary board to a secondary board to a primary board.. inelegant, but functional for many. Having said that, the gentleman with the CubeECU, malcom2073, may have a better idea!

I'll come right out and say it, I'm hoping to get it up and running on M$2 Extra. No intentions to clone anything, I'll use the genuine B&G daughtercard, and I'll run a jumper or two from the 3.0 board when I do it to make my project more of a breakout board. Once I'm convinced my boards will work, I'll jump over to the FreeEMS on a COP/batch fire on my test rig- a mighty Hilux which I shall go off and make a users ride thread about.

Thanks again for the feedback, Fred (and anyone else who wants to get stuck in!). It's a free education for me, and I appreciate it, and the work you are doing here, heaps. Keep it up!

cheers,

Ash
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Re: A nephelyte's approach to EMS

Post by Fred »

You're most welcome! However, if I'd realised that you were an ozzy and could likely take some ribbing, I'd have given you more shit :-)

I tend to say "ignitor drives" as different to "ignition drives" the latter meaning "can drive coil" to me, anyway. Use FET drivers for this task, they've got the balls to provide a solid signal and can drive normal ignitors hard enough should you decide to use a different coil.

There is another user on this forum in WA, and my ex, now married, too. Maybe you'll get a PM from him and get in touch locally for a beer and bullshit. He's been privy to quite a few things not yet published, which I'm sure he'd be happy to show you if you do bump into each other. Or, he may not see this. I won't be pointing it out :-)

MrOnion used your strategy to test his OnionBoard setup, here's a picture of it, censored:

Image



More info here: viewtopic.php?f=62&t=1971

Hiluxes are indeed mighty, i look forward to the thread! :-)

Fred.
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Re: A nephelyte's approach to EMS

Post by wraith »

Still working on that users ride thread..

Have purchased a couple of the 144 pin adapters from http://www.futurlec.com/SMD_Adapters.shtml Once they arrive, I'll get my SMT man to solder the Freescale chip to the board. Element14 have the XDP512VAG for about half the price of anything else, but with a steep lead time. If it takes too long, I'll get them elsewhere.

I've got an adapter board mostly laid out to bring the headers down to a 40 pin DIL. The nice thing about that is that it ought to work both ways, 40 pin onto my custom board, or to adapt the XDP512 to my current board. That could prove very useful for testing! I need to add circuits to my adapter board for the clock and various grounds and capacitors, and make sure I've got my power feeds sorted out right. I'll post my schematic and gerber here when I'm done, so that it can be critiqued before I send it off. I'll also be looking to add double ended header pins to the processor board so that I can pull off injector and ignitor signals straight to something like the JBPerf 4 channel driver board. I'll probably look at a separate VR input board too.

This also means a bit of a shift in my plans- I'm hoping to get the FreeEMS firmware running on the XDP512, on the proprietary board first. Touch wood that I don't fry one of my daughterboards- though it looks like they should come in at under $20AU assembled. If I can get that up and running, I'll be able to test FreeEMS in sequential / wasted spark and batch fire / COP. Then I'll have another look at my board stack concept.

I'm hoping to run in a 36+1, dual trigger VR mode. Unfortunately, the page that talks about input options for FreeEMS seems to be broken? If you end up reading this Fred, let me know.

Cheers!

Ash
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Re: A nephelyte's approach to EMS

Post by Fred »

wraith wrote:I'm hoping to run in a 36+1, dual trigger VR mode. Unfortunately, the page that talks about input options for FreeEMS seems to be broken?
36 even on crank, single sync pulse on cam? That's about the highest you can go before you risk losing sync due to edges crossing, but should be fine. Link to broken page?
wraith wrote:If you end up reading this Fred, let me know.
Every post, always, checked hundreds of times per day, like I'm obsessed, or something.
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Re: A nephelyte's approach to EMS

Post by wraith »

viewtopic.php?f=54&t=1241

links to

https://github.com/fredcooke/freeems-va ... /STATUS.md

which gives me a 404 not found.

but then I went digging! and got

https://github.com/fredcooke/freeems-va ... n/decoders

And I'm still confused, but I'd blame me for that.

Actually, that should be 36 teeth on cam, plus 1 on cam. Although it's possible I could tap a VR sensor into the timing cover to get 18 on the crank? I believe the current propriety system requires a tooth number divisible by 4, though.
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Re: A nephelyte's approach to EMS

Post by Fred »

Ahh, yeah, I should fix that...

Missing tooth is slow/inefficient/limited. 60-2 = 2500RPM, 36-1 = 5000RPM, 24-1 = 7500, etc.

Various other decoders are available too, of varying quality.

Even tooth is usable in that config, and any other, efficiently, to any RPM up to 32767.5 :-) 36 + 1 on cam is totally fine, no chance of skipping there, though.

Re "the current propriety system requires a tooth number divisible by 4" I invite you to run prime numbers. No one has done it yet, but the system couldn't care less.

PMing you another out of date link that's more up to date.

Skype for a chat soon? PM me back if so.

Fred.
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
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FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
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