[Diy_efi] Re: Minimalist micro based EFI ?

[Bevan Weiss]

> Hello Mike,
>
> > MAF, analog, 10 - 12 bits, what resolution are people using ?
> > Adjust MAF, 10 - 12 bits, is 10 bits enough ?
> > Temp, analog,  10 bits should be plenty ?
> > O2, analog, 10 - 12 bits, is 10 bits enough ?
> > CAS, 2 digital timing to prescaler/counters
> > Injector outputs, 4, 6, 8 to suit coil types
> > Aux air control, PWM - 1 digital line
> > TPS, mine is a pulsed with idle switch so all digital.
>
> I think 10 clean AD bits (with proper analog levels)
> should be enough for any of the analog signals here.
> (I mean without much oversampling - of course).
>
> You cannot make it much simpler than megasquirt.
> I'd like to make it with atmega128 one day, with an
> event-queue based approach to have lotsof outputs with
> precise timing control(seq. injector and ignition) without
> hardware support (TPU) for that many channels.
>
> I heard a guy was about to do something similar (atmega128),
> but I could not find him, although sharing a pcb would
> be nice. The board will be quite general,
> usable for many other purposes. (and low cost btw).
> http://x-dsl.hu/genboard/
> I hope one day I'll have time to go and finish it.
> If anyone is up to it, I will assist of course.
>
> Marcell

I believe that there was a link to the atmega128 controller from the
megasquirt website.

I agree that 10bits should be adequate.  That gives 1024 codes...
which means on a 0->5V sensor, that's 4.8mV or similar.  I would imagine
that noise on the line would be greater than this, and hence the only real
way to remove it would be to oversample, which is not worth it in this kind
of environment anyway.

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