I think I am running into limitations of the MC68HC908.
I think I need another timer module for the dwell calcs.
Since I am doing another board anyway I am thinking putting a
faster and better processor on it.
Not much different in cost and some of the later Megasquirt asm
programs will work. The same processor is used on the daughter card.
However there is other stuff on the daughter card we don't need. GM
stepper IAC control not needed. CANBus communications for interface
with GPIO Board, IO Extender, or other devices.
DIYautotune wants $199 for the daughter card but you still have to
pay another $250 for the mother board.
Why not? Just a few extra bucks for the processor. $10 total
roughly. You can never have enough I/O. http://tinyurl.com/755wdzh
The MC9SC64 has no ROM in it. You flash the whole program in it.
It has 64K flash and 4K RAM.
Here is a list of feature.
Paul Lamar
I'm for the better processor. Like you said, you can never have
too many I/O's... especially if you foresee integrating an EFIS, etc.
Josh
The software for that is already done. Both in the megasquirt
and the PC. Over the years a tremendous amount of work has been
done. It pays to take advantage of that.
Paul Lamar
G'day Paul, Josh
I 'm totally out to lunch when it comes to EFI but I have a few
points/questions
1. does an o2 sensor adjust the fuel to acheive clean burning ( to
pass smog laws) or does it just give us a reading? This may foil our
efforts to adjust AFR for lean burn and best power.
2. if the sensor is clogged by solid lead accumulation, perhaps we
could move the pick-up out of the direct airflow by placing it in
a recessed position or behind a shroud/deflector. this will still
analyze the exhaust but protect it from lead accretion. So I
thought I would search to see if I could find a lead safe O2
sensor and found this info. I reckon that this may mean more to you
Paul than I.
http://www.factorypro.com/dyno/dyno_ec997,eddycurrent,mc,dynamometer.html.
Also try the links at the bottom of the page.
Maybe if we used a TPS that would shift AFR to best power at wot and
best economy below 75%. Or perhaps different power maps as the
race boys use for power/economy modes. Back to you. Graeme Riley
1. Usually the O2 sensor system are set to stoichiometric or
about 14.7:1 air fuel ratio. It depends on what kind of smog you
are talking about. If you are talking about NOx yes this gives a
low smog number but at a severe fuel burn penalty. Lean burn high
NOs gives a better BSFC. Long story but here is a bit about it. B.
Bruce-Biggs. The War Against the Automobile. Dutton. 1977 book
explains it the best. Don't get me started :)
2. They might be one to something.
http://tinyurl.com/cps7v2o
Paul Lamar
1. If you're using a wideband O2 sensor, Megasquirt can adjust the
fuel to any target AFR that you specify. I believe you can even
specify different AFRs in a MAP vs RPM table so that you can target
different afr's in different situations. If you're using the narrow
band variety, it can target 14.7:1 only. In either case, the AFR
"seeking" function is optional. You can have it just give the
readout.
2. I'm not sure if shielding the sensor would help with lead
accumulation or not. It would be interesting to see if it works.
Josh
The new chips are surface mount and a lot smaller. I was never
really fond of DB connectors for aircraft use anyway. Ten times
easier to wire. What do you guys think of a smaller, lower cost
board with these connectors?
This board is 3.9 inches by 2.5 and is stackable. One rotor, two
rotors, three rotors or four. The heat sink on the top will double
as a spacer. In and out are separate. Input on the left and output
on the right.
Paul Lamar
I've used those connectors for connecting signaling wires to controller
panels. They are much easier to connect than having to install pins
in a DB connector. You would have to be sure to secure the wires
close to the connectors to avoid issues with metal fatigue at the connectors.
The clamping devices in the connectors deform the wire raising a stress
point. If the wires are not secured close to the connections then
vibration and flexing of the wire will lead to connection failure.
DB connectors deal with this by securing the wires in the back
shell so that there is minimal stress on the connections.
Mark LaPierre
I have an AV8 Audio Flight Avionics device in my RV4 that uses these
connectors. What they did is crimp hollow connector male pin on the
end of the wire and insert that into heat shrink tubing. That
eliminates the stress concentration. Basically the same as the pins
in a DB connector. In fact they are the same male crimp pins bought
in bulk.
http://www.aeroelectric.com/articles/dsubs/d_solder.html
Paul Lamar
I have used similar in plant situations. Usually there they supply ones with
insulation similar to regular blade, ring and fork stake-ons. They work great
as the wires frey, break and are a pain to get into the socket so you can
clamp them. Small cost of a bag or box is more than offset by peace of mind.
Dale Davies
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