Hello Paul & Group,

There was an "Ultra-squirt" project going on about two years ago. Seems
that it didn't materialize, but the hardware choice was interesting:

Freescale MPC55xx - 32-bit PowerPC core, programmable eTPU timer for
ignition + injection, DSP knock indication built-in, CAN bus, plenty of
i/o, good set of driver/sensor circuits.

What's interesting here, is that - if i understood correctly - the eTPU
unit offloads the ignition/injection timing task from processor, and it
is still fault-tolerant (ie. missing teeth, no CAS signal etc.)

Here's some video clips. Not really a proper product introduction, but
gives an idea how eTPU works.

Using the Engine Position eTPU Functions - Freescale Application Note: 3769
http://www.youtube.com/watch?v=a1NplNEAaww

eTPU Set 2 Simulator Demo
http://www.youtube.com/watch?v=Mu_zBkoByVQ

Link to Freescale eTPU user guides:
http://tinyurl.com/2wzw45p

Back then, the required CodeWarrior version cost $5000, now it is $955
or $1955 - the difference seems to be the "Optimizing C/C++ compiler"
Runs on Linux or win2k - 7, new version 10.0 within Eclipse. Yes that's
more than OSS price, but... it ought to be good.

It seems that this is the best platform to develop a really capable
FADEC product for rotary engines.
...Just that there should be someone involved who could (and will ;)
make neat C code...

Anyone tried 55xx / 56xx?


  Petri Flander


I have code warrior for some of the smaller Free Scale chips but what
I don't like about it is the  C or assembly language required.

Atmel ZBasic is an order of magnitude easier to learn and
faster to program. There are some trade off as a bit more hardware
is required. It is fast enough for simple AC engine EFI and EFIS.

Paul Lamar

There is the earlier TPU in the 68332 & MPC555, and the later
eTPU in the MPC55xx series family. They are state machines and
not that difficult to learn if you can dedicate the time to
understanding what the TPU is doing.  The Motorola programming
manuals are not the easiest to understand.  Munir Bannoura
taught the classes on the TPU and eTPU and wrote his own books
after seeing students struggle in class with the state machines.
Once I listed every command on a Excell Spreadsheet with the
allowed states and how to enter and exit each, it made it much
easier to understand.

Once you understand the state machine, and what is allowed from
one state to the next you still need to spend sometime to write
the microcode.  Advantage is that once you understand that, and
can write the code, it is a great tool and also excellent for
your resume!

TPU is very handy for conditions changing constantly with a
modern emissions equipped engine meeting EPA standards.  Since
the TPU can run autonomous of the engine controller, it greatly
helps reduce the overhead of the controller to focus on real
time calculations. It is one of the few embedded controllers
with a floating point processor for real time calculations, so
that off loading the main processor is a critical function.
For a simple aircraft engine control, it is way overkill.  Most
simple 8 bit micro controllers will work fine, and even having
two microcontrollers for redundancy is easily done.

I still have my MPC555 boards and logic analyzer, but there are
so many hours in the day and to many other projects before I
could revisit the TPU programming.  I was paid nicely for TPU
code, but only way I would take that up again is if I lived in
the Bahama's and limited myself to four hours a day of
microcoding, and the rest of the time flying, fishing, and
sailing. Now that would be the life!

As to tools, do look at the gcc compilers. There was some great
work on uC/OS (Jean Labrosse's royality free RTOS for personal
use) put together by a French University on the MPC555.

Petri,



Tom Walter