FreeEMS hardware feature wishlist (your suggestions here!)

[Fred]

Guys, Aaron already started such a thread :

http://www.diyefi.org/forum/viewtopic.php?f=8&t=146

Though, my take is only unasked questions are dumb!

Good ramblings bmcd.

In our case rpm input is handled by two input capture channels that in hardware record the time of an event and then send a high priority interrupt out to do something about it. This is better than just sending an interrupt and pretending it happened when you start running as there is always latency on an ISR, and that latency is not a fixed value.

Interesting project you have going on there bmcd, one of our other members "nastnas" has a msed Jetta too. Also, KW1252 would be interested in your dash project, I hope he sees this. You should slap up a thread with some pics etc if you have any :-)

[thebigmacd]

Sorry Admin, no pics yet, still waiting for a bunch of stuff from Parallax. All I have so far is dozens of drawings and flow charts on a notepad.

I promise it won't be a dead-end project though...I can't put my dash back in the car until I have the gauges/displays working and installed, and the dash is ready to go in as we speak. I will be sure to share my progress.

[Fred]

Excellent, I'll look forward to it :-)

[GartnerProspect]

Sorry Admin, no pics yet, still waiting for a bunch of stuff from Parallax. All I have so far is dozens of drawings and flow charts on a notepad.

I promise it won't be a dead-end project though...I can't put my dash back in the car until I have the gauges/displays working and installed, and the dash is ready to go in as we speak. I will be sure to share my progress.

A NOTEPAD!

Come on! Napkins are so much better. They fit in your pocket, are variable in both shape and size, can subsitute for a kleenex or schematic, and can be found virtually anywhere!

[AbeFM]

One could even go as far as defining standard PCB sizes like IT-style rack sizing (1U,2U,3U etc). A single injection IGBT driver could be on a 1U board, or use a 2U size and fit 4 on or something. Scalability and modularity.

And another alternative: define a rather large standard PCB, design a layout that can support all of the I/O one could ever imagine, but design it in such a way that each I/O channel has its own standard real estate on the board. If you want only two injector drivers, just populate two of the injector driver sections. Although the cost of the PCB in terms of physical size would be higher, there could be a lot of money saved on connectors over my first idea while still eliminating most of the jumper wires associated with MS.

Hey, I like pc104! Here we have a 'standard' that only our company and the few who buy stuff from us (along with a university or two) use, a "pc-104 stretch", which drops one of the connectors, and gives you quite a bit of space. The reason for the large spacing is when stacking cards you need to have room for stuff above and below, and especially when it comes to power handling, you can always use it up. Anyway, at least here, (while there is an allowable range to still be in spec) we've been sticking with 0.700" board spacing (center to center).

But I'll admit, small boards, the size of a typical, connector laden pc104 board, or the size of the current freeems, mean a lot of stacking, and a somewhat flatter box is a lot easier to put in a car (also to put a display on. heh). The idea of a large flat board seems pretty nice. In truth, the MS-box is a decent shape, and I would shoot for something similar to that, with connectors all on one side, and maybe up to an inch bigger in any direction.

Us miata folks are pretty space conscious.

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Everyone knows 'back of the envelope' designs are to be done on envelopes. Don't be daft.

[Fred]

The euro card is the same size as the MS boards, just metric as it should be in 2008. I think we could do around the 12mm per board mark if careful. that means that we'd be sitting on 36mm with 2+cpu or maybe 48 with a bit of room to move. how thick is a MS box? I forget.

[KW1252]

160x100mm board size FTW

And yeah, I'm VERY interested seeing the digidash progress!

[AbeFM]

It's hard to imagine needing more than 2 boards... I guess that depends on if you use the board you're using now for the ECU or not...

[Fred]

That depends on how much stuff we get on two :-) If we only manage to condition 25 in and 25 out, that leaves another 50 for other boards. That increases even more if you use other chips and data connections. I can't see myself needing any more digital pins, but I can see myself wanting a bunch more ADC's for various things. It's gotta be fairly quick and easy to sample ADC's and log them. Stuff like continuous barometer, pre intercooler, post intercooler, post throttle MAP sensors, possibly even map sensor per runner (even on a non-itb car), ambient air, inlet air, inlet air after cooler, manifold air temp, oil temp, oil pressure, shock pots, all the usual sensors etc :-)

[AbeFM]

Just having a discussion offline with Fred, and I had an idea for a feature, but not sure if it's generally useful.

Can anyone thing of any uses for a pin which would go high/low based on engine position (programmable, maybe dependant on RPM).

The one that leaps to mind for me is knock sensing. SAy you have the line go low when the motor is ign-5*, and stays there until ign+15*. As the motor speeds up, you might want to have this be a little longer, or a little earlier (as the velocities in the gas are a bit higher).... And you could use this as a mask to the knock sensing circuit.

If it's only that, you could do it in software or interupt masking. But it seems like a neat thing to do....

Just need to come up with strange and wonderful things to do with it.
-Abe.