Potential Bulk Buy for FreeEMS first edition PCB

[Fred]

I've posted a feeler thread for a bulk buy on an initial FreeEMS board in the BB section. Please post once each in it and with reasonable detail/description of what you are and aren't interested in. Any other discussion about where they should be made, how much they will cost, what is wrong with my list etc etc etc belongs in this thread here.

The feeler :

http://www.diyefi.org/forum/viewtopic.php?f=38&t=406

Fred.

[Fred]

Abe brought up some further points, so I adjusted both his and my posts. Abe, sort out your post again based on the following and what I changed in it (red).

wideband input in analog will be included along with water/air temp and tps and map and other normal stuff.
egt is an expansion thing and not core to normal use for most people (besides, if you built your setup right you know it's within spec anyway)
knock sensor will probably be an expansion thing mainly because we don't have a game plan for it at this stage and it's a safety net and not core anyway
secondary staged injectors are an expansion thing too

expansion is easy though, so no worries with any of those IMO.

Thanks for bringing up spare IO. I also would strongly like 2 relay drives and 2 PWM outputs, though neither are critical... I edited my post to reflect that.

Fred.

[Fred]

Gearhead, what is "ELCD" ?

[Fred]

For those wanting heaps of extra inputs and auxiliary outputs on the main board, please consider how easy it is to plug in a card with conditioning for a dozen more ins and a dozen more outs. Very easy. Hence I think this should focus on what your average dude needs.

Normal stuff could include some of :

boost pwm FET = optional, even for boosted motors, poor example
idle pwm FET - many/most have this
radiator fans x 2 on/off relay drives - many/most would want this
tacho on/off low current drive - many/most would want this

All the rest really belongs on expansion boards IMO. At least for the initial board! I personally will want a LOT of I/O for my applications, but I don't think much of it should be covered by this board. I think it should go on an add in board of some sort. It would be very very easy to create something to do that sort of thing even with strip board.

Fred.

[AbeFM]

A side comment, from my perch here on my high horse:

This is a *prototype* board people! Almost everyone seems to get it, but we're not building a finished product. And, wanting more than one is almost crazy. There will be bugs and changes and lessons learned, so don't go telling customers we'll be shipping in three weeks. This is the minimum we can do to look for obvious issues, see if spark and fuel work.

Things like GPIO are listed primarily so I don't have to come up with an additional controller just to run my fans.

I think if lots of that other stuff wants to find it's way in, expansion boards are the way to go. It would be funny to have those built before the main board.

One more thought: This board doesn't need to do everything, for that matter, you can recycle the CPU card, so even if you throw this board away you haven't lost much.

How much space are we talking about for the IGBTs? Can we just not populate?
I really like the idea of current sensing on a second card - not because I don't want it, but it does seem like something which would impact the whole board heavily? Perhaps not, it's only 1 resistor per fuel injector.

Lastly: What's the whole thermister thing? I guess I don't care. I would think people could leave it off or jumper it if they don't want it active, so why are people hating on it so much?

Edit: Definitely want to see some good hall-sensor inputs!! I'm going to be pretty insistent on this one!

[gearhead]

'good hall sensor inputs'?

An inline resistor and a 5V pullup works fine for mine. A hall input is like falling off a log. It is already digital. A 5V pullup, inline current limiting resistor and a small cap for noise and you are set. If you want/need opto, that can be added as well, but definitely not needed.

I guess I do not get this one. Now if it were 'good VR input' I would understand, but we have noly talked about an LM1815 which seems to be good enough for just about every OEM out there, so it will be good enough for me even though I do not run VR.

Gearhead

[AbeFM]

I have another thread with more details, but... I've tried a bunch of variations on the resistor, resistor-cap, resistor-cap-transistor, resistor-cap-resistor-transistor-cap-resistor, resistor-cap-resistor-transistor-cap-resistor-transistor-resistor etc inputs, and they don't deal well with noise.

Yes the signal is digital, no it's no always easy to read it. But I don't want to pollute two threads by cross posting, please comment in http://www.diyefi.org/forum/viewtopic.p ... 412&p=4548

[Fred]

Abe, great comments :-) I moved them here though, I hope you don't mind. I kinda want to see what people think unreigned. We can always hall them back in a bit :-)

Gearhead, he's talking about noise immunity PRE the processor. I think if it works as advertised that it is a good thing to have. I intend to keep the inputs noise immune in software, but noise will generate an interrupt load if present at the very least.

I don't see the thermistor thing as a big deal. Jared wants to include it to prevent self heating of the thermistors for his application. It will be bridged by default and not take much space, so impact is minimal. Current "sense" on the other hand could pose a large impact and if it does, I'm anti it.

In the mean time, there are a few people I might have expected to see on that list not present... hmm...

Fred.

[gearhead]

Gearhead, what is "ELCD" ?

Evaporative Loss Control Device.

Basically, a solenoid valve on the charcoal canister. Not absolutely necessary. I plugged the vacuum line so that it is not a leak, but I'd like to get it to work properly.

Gearhead

[gearhead]

Gearhead, he's talking about noise immunity PRE the processor. I think if it works as advertised that it is a good thing to have. I intend to keep the inputs noise immune in software, but noise will generate an interrupt load if present at the very least.
Fred.

So am I. I guess I just don't get it 'cause I have not had any issues with noise getting into my EFI unit from this source. Twisted pair works reasonably for VR due to the high voltages present. Shielded cable and a low pass has not been a problem for most OEM installs that use a hall.

In my install, i have no twisted pair or shielding, currently, and have not had any noise problems with: dizzy+single coil, Ford W/S coilpack or CDI ignition unit The sparkers are the devices that generate the most noise. My guess is that with a proper grounding and power scheme, this will become a non-issue.

Gearhead