Hello

[David Cooley]

Hello..
Forgot to introduce myself.
I am Dave Cooley.  No college, worked for Hughes Aircraft for 5 yrs in 
Test equipment and pc repair, now have worked for 6 yrs for Siemens 
Medical Systems repairing and maintaining MRI and Cat scan systems.
As I mentioned before, I am designing and building my own J1850/OBDII
interface to hook onboard computers to laptops.  The J1850 BUS looks like 
a very good system for this project to interface all facets together with 
and is very simple.  CPU hooks to 2 chips and the output is at J1850.  It 
is a single wire, High noise immune system.  Harris semiconductor makes 
the chips and they will interface with just about any micro.  They are 
also very inexpensive.  Harris makes most of the internals for the 
Chrysler PCM's, and has a lot of dedicated chips. IE Knock Sensor system 
(1 chip) Injector drivers, Electronic ignition drivers etc.  Their parts 
are all very inexpensive and the CPU's of these PCM's are based on the 
motorols MC68HC05.  Harris calls it the HIP7030A0.  It is a 6805 without 
eeprom or ram.  $25.00 retail.  Just like the 'hc05, it comes as masked 
rom, eeprom, ram etc.  I am sort of reverse engineering, as they are 
designing for the Auto makers PCM usage, but I just have to change the 
code in my controller.  This bus interface will also allow the design of 
an ECM here to be OBD_II compliant and possibly be used on the road 
legally.  By 1998, all vehicles in the US have to be OBD_II compliant.
Just a suggestion, but this will keep this project on top of technology!
Best part, again, is low cost.  The 2 interface chips are 6.00 each retail.
Thanks,
Dave Cooley
cooldave at nando.net