AC Delco ECU

[peter paul fenske]

>>chomp.....
>>I'm told that it is based on a Motoralla 68HC11?? controller. Is this
>
>Bill,
>
>About 1987, I had my hands on the complete source code for the DE ECU of the

>The processor is a 68HC11.  I wrote some code for the computer using a cross
>Munch.......
>Someone with more recent experience may be able to add more.
>
>Paul
>
>Hi gang
>Here are some details of the GM ECM.
>The MPU is based on a HC11 core called in GMese a GMP4. Thats where
>the similiarity ends. On the board there is a co-processor called
>a ECU( engine control unit) which handles engine timing functions.
>Via an internal serial buss the MPU also communicates with a FMD
>(fuel moding device) and a custom A-D chip. There is also a custom
>back-up fuel device called a RFD(reduntant fuel device). This provides
>backup should the main system fail. Calibration is in the calpak
>via calibrated resistor packages. In the calpak is a eprom which
>contains "most" of the code. This can be a 64,128, or 256 eprom
>depending on year. In addition there is an aux memory connector
>to which several development tools can be plugged in
>There is ram from 0 -255. The stack is 255 down. Variables
>0 and up. Eprom runs from 8000 or C000 or 4000H up. 
>There is considerable IO in the 4000H region. Quite a bit
>of chatting with the co-pro and lots of counter timers
>Anyways there are some unknowns to me. The interrupts go to
>6000H. These routines are essential. I don't know where.
>Could be eprom is remapped. Lots of the IO is unknown to me
>There is a interrupt heartbeat of 12.5 ms. It looks like
>the main code runs at this heartbeat. TPS delta, O2 activity et al.
>
>Anyways help would be greatly appreciated. It took me two weeks
>to figure out the CTS algorithm. And thank everyone on the net 
>for your help.  Longer than that for spark.
>If anyone has additional info they want to share please please
>post it. Or sent it to me if you would rather. Any thing no 
>matter how minor is an asset when you are working with 20K of
>machine code.
>GL all: peter ---- pfenske at direct.ca