This looks like a real simple way of using megasquirts on rotaries and
you have
redundancy. The engine will run on one rotor. It solves a lot of
problems using just
one Megasquirt on a rotary.
I has the advantage of using a notebook computer with a USB connector
to tune and
save injector tables to share with other people merely by emailing
them.
Megatune is very sophisticated and easy to use tuning software that
runs on a
notebook.
IMHO this is a great idea.
Paul Lamar
-----------------------------------------------------------
Using MegaSquirt ‘out of the .box’
www.not2fast.com/megasquirt/doc/rotary_injection.doc
MegaSquirt introduction.
The MegaSquirt was design by Bruce Bowling and Al Grippo to be a
simple and cheap
batch fire fuel injection system. Been around for years.
There are 2 injector driver outputs on the MegaSquirt, running off the
PWM channels
of the MCU. This allows both saturated and peak and hold injectors to
be used on the
same hardware: very clever. This allows 2 different injection events
to occur in
parallel, which suits our purposes very nicely.
Specific needs of Rotary engines.
The rotary engine, due to the rotor layout has a few key differences
with a
reciprocating engine. Many of these work in our favor. And remember,
the otto cycle
is the otto cycle:
There are 2 rotors, spaced 180° apart. EFI.
Build 2 MegaSquirts.
Fit a pair of hall effect sensors one at 22 degrees BTDC and one 180°
later (top and
bottom) Hook one MegaSquirt to the top sensor and one to the bottom.
Burn in injector staging code if required.
Ignition.
The ignition pulse on 1 rotor corresponds to 22° BTDC on the inlet
cycle of the other
rotor, give or take the amount of advance being used. Very handy.
Use 2 MSD capacitor discharge units per rotor. One per plug. This is
what the racers
do and is it very simple and straight forward. Each Hall Effect sensor
fires two MSD
units 22 degree BTDC.
Injection.
Around 220-280° is available for injection. In a reciprocating engine,
you
can ‘puddle’ fuel on the inlet port to increase the injection time. In
a rotary there
is little time for this before the next inlet cycle starts. This
forces relatively
large injectors to be used, with staged injection being a
useful method of getting high max flow rates and a good dynamic range.
For example,
at 8000 RPM 1 revolution is 7.5ms, giving around 6ms for injection.
In terms of injector strategies there are a couple in general use
The best for our use here is 2 injectors in each runner.
The code mods are very simple, if needed at all
You get the full 6 ms for injection at high RPM
2 MegaSquirts are needed so adding a full $100 to the costs
Tuning will be a little more tricky as you have to set each parameter
twice
----------------------------------------------------------------
I had an idea of using 3 megasquirts that fed a logic box that compares
the outputs
and forwards the one that at least 2 ms boxes agree on. Not sure if it's
really
feasible since that would induce some lag in the outputs.
Joshua
---------------------------------------------------------------------
SymTech Labs' coolant temperature sensor is a standard GM CLT sensor
capable of
interfacing with all MegaSquirt ECU's. It features 3/8" NPT threads and
can also be
used as an intake air temperature sensor (IAT/MAT). Each unit is shipped
with a 6"
pigtail for easy installation.
Intake Air Temp/Manifold Air Temp
The big question that I have is there seems to be conflicting info.
Often they talk
about a MAP sensor but this block diagram does not show it. A Manifold
Air Pressure
sensor (MAP) can be used to control the amount of fuel injected just
like an O2
sensor. That is what Tracy does.
Any type of feed back from an O2 sensor will not work as 100LL is death
to O2 sensors.
The MS flow chart shows a read of the MAP but the schematic shows no
connection to a
MAP sensor.
Can anybody help me out on this? Is the sensor on the mother board?
Where is it
connected?
BTW The megasquirt has the built in capability to send engine parameters
back to the
notebook in real time for use as an EFIS. The notebook software is
already available
to display these engine parms in real time. This is a real cheap EFIS.
Paul Lamar
The MS3x has the map in the box. An external map can be used for
Barometric correction.
I have one. Tuning software is Tuner Studio which runs on both Windows
and Linux and megatunix which just runs in Linux.
chris smale
I have already found a way to flash a 68HC11.
http://www.orgler.it/swflash.htm
Apparently AMD makes a clone.
-------------------------------------------------------
Here is a new part directly from the maker probably more powerful than
the original
MS part.
http://www.newark.com/freescale-semiconductor/mc68hc908jl8cspe/8bit-mcu-8k-flash-adc-68hc908-dip/dp/92K6991
$3.97 Three dollars and 97 cents qty one. :)
Runs MS code directly.
I have a set of MS V3 boards already that I can copy if need be.
The more I can get into this the more I like it. I am getting excited
because of the EFIS and data logging MS software is already done.
Six months ago I was thinking of writing all the software myself for a
different
processor. This is a much quicker way of dong it. Just port the MS
software and copy
the hardware to an aircraft specific system.
Paul Lamar
Sign me up. Let me know what you need from me for 2 boards. I can get the
chips, and the MS schematic is on he site I think.
Kevin
We can buy boards off the shelf. Here is but one.
http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=ZK-HC08EY-A&fsrch=1&sr=8
The ZK-HC08EY-A Starter Kit is a full-featured, ready-to-use evaluation board for
Freescale MC68HC908EY microcontrollers. A 32-pin Yamaichi QFP ZIF (Zero Insertion
Force) socket is provided which allows easy microcontroller insertion/extraction--the
Starter Kit can be used as a single programmer. The Starter Kit takes advantage of
the CodeWarrior Development Studio Special Edition (which groups an Editor,
Assembler, C Compiler and Debugger) and the Freescale MON08 interface, which allows
the download and debug of the user application into the microcontroller's FLASH
memory. Together with CodeWarrior, the Starter Kit provides you with everything you
need to write, compile, download, in-circuit emulate and debug user code. Full-speed
program execution allows you to perform hardware and software testing in real time.
The Starter Kit is connected to the host PC through a USB port. A prototyping area
allows you to wire your own small application.
Features
Full-Featured Evaluation Board with LIN, RS-232, LEDs, Push-Buttons,
DIP-Switches, Potentiometer
ZIF Socket for Experimenting with Different Microcontrollers
True, Built-In MON08 Debugging through USB Interface
CodeWarrior Development Studio Special Edition Included, with Editor, Assembler,
C Compiler and Debugger
http://www.freescale.com/webapp/sps/site/homepage.jsp?code=CW_HOME
I don't know why I did not think of this five years OK.
Paul Lamar
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