[Diy_efi] Data Logger CPU schematic and C for review

[Adam Wade]

--- "Steven P. Donegan" <steve at donegan.org> wrote:

> The ION stuff is basically watching for spark plug
> event, then for 2-3 curves in data and finding the
> correct ones - one indicates ping, one is peak
> pressure - there are others... It's been done
> on a slow 32 bit controller so it should be do-able
> on the ARM...

The difficulty comes in wanting to go beyond a few
simple basic curves to more complex data; for
instance, closed-loop spark control that can "see"
ping and PPP timing, or closed-loop fueling control
from watching vagaries in the ion trace that indicate
different end gas compositions.  This is where FFT
becomes necessary, since you have essentially several
sets of low-signal data all meshed together.  For
basic patytern-matching, though, a LUT would probably
be acceptable, provided you weren't running an engine
where the normal ion trace was fairly close to one of
those in the "library"; the trace will vary with
combustion chamber size, heat of combustion,
combustion speed, fuel mixture, spark timing...  And
so on.

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