[Diy_efi] Data logging..

Perry Harrington pedward at apsoft.com
Sat May 11 18:33:38 GMT 2002


On Sat, May 11, 2002 at 04:42:54PM +0300, Antti Lehtonen wrote:
> 
> On 11.05.2002 at 01:36 Perry Harrington wrote:
> 
> >I'm working on such a product.
> 
> 	Sounds good..
> >
> >The production version will support 8 analog channels (1 dedicated
> >to battery voltage), tach, and vehicle speed.  I have bench tested
> >the unit and get about 134 samples a second at 38400 baud.
> 
> 	Even better.. But is there any for injector opening
> 	time? As far as I can count: rmp, speed, maf, map,
> 	intake temp, throttle position, injector open time, and
> 	one more to spare, I don't see any point to monitor
> 	constant 12v from battery, I personally use only working
> 	batteries ;)
> 

The system has 2 hardware driven timers for the tach and VSS.  These have
a resolution of 1ms with the test hardware.  The production unit will have
a resolution of 100us.

The AD inputs are intended *only* for A/D.  I am considering breaking out
the other 2 channels so that there would be 2 additional timing inputs.

The system as I see it (on my Mustang) would have these sources to monitor:

MAF, TPS, ECT, ACT, L-HEGO, R-HEGO, BARO, OIL TEMP, RPM, VSS.

I count 8 analogs and 2 digital signals.  So the production version could
sample 7 of those, throwing out one of the hegos.

Realistically, I'm interested in logging MAF, ECT, and L-HEGO.  That's what
I'll hook the AD inputs to on my test version.

I had already contemplated adding additional timer inputs so that I could
get injector PW and derive MPG.

> >The final product should give ~100 samples per second with 10bit
> >ADC resolution.
> >
> >I have built one prototype (with 4 ADC channels) and am working on
> >the head unit software (a display device which shows the data in
> >realtime).
> 
> 	This is just what we need..
> 
> 
> >I plan on selling the setup for about $750US.  I will also sell the
> >datalogging module separately.
> 
> 	Well this is the place where everything comes crashing down,
> 	extensive surfing has given me so idea what things costs, 
> 	for that kind of money I can go to tag heur or some other
> 	professional, (etas) and use their ready products, take a
> 	look at this thing:
> http://www.bb-europe.com/product.asp?dept%5Fid=119&sku=UD128A8D
> 	I would pay 100-200$ for your product because this seems to
> 	do what I want 1/3 of the price..

That product looks very keen for what you want.  It has a faster iface,
so it has a higher sample rate.  Although it does require USB, and only
works in Windows.  It also doesn't have any onboard timers according to
the page, so your peak resolution is only as good as the USB interface
and local computer's clock.  My product provides a MS resolution clock
with every packet.  The timer inputs are provided as count and period
length, so the math isn't time dependent.

> 
> >What's your timeframe for needing such a product?
> >
> 
> 	That's hard part too, this season (summer, short at our part of the world)

Go ahead and try that logger above.  Perhaps I'll have something for you
at another time.  I don't want to pull an Osborne and hype my future product
intentions.  However, I will say that a future design will have a much higher
sample rate and have removable storage for datalogs (think smartmedia).

--Perry

-- 
Perry Harrington             Linux rules all OSes.               APSoft      ()
perry at apsoft dot com 			                 Think Blue. /\

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin


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