Mopar / 6803

[Chad Clendening]

Lets keep the interest on this ECM alive.

I have been working on the 85 logic module for a while.  While using an older
processor complicates things by not having nice brset or bset instructions of the
HC11
( or even the divide ones), ALL components on this board are -or were- standard
off the shelf components.  Data sheets on these are readily available.

I havn't finished the fuel calculations yet, but the spark consists mainly of the
following "tables"
advance vs MAP ( coolant cold) or  advance vs MAP ( coolant warm)
EGR advance correction vs MAP
base spark vs RPM
advance barometric pressure correction vs MAP
barometric pressure correction phaseout vs RPM
max advance vs RPM
max advance vs TPS

It has been previously said these don't use tables.
The "tables" in these ECM's are not the typical  8 x 8 type, 2 variable in and 1
output of the GM's.  The 2 differant lookup routines work
on a Y = mX + b system where m and b are in the tables.  The easiest way of
explaining it would be
a C array of structures.  This is one of the types.

struct  tablestruct
{
unsigned char min_comparison;
unsigned int m
unsigned int b
}

Then  the actual table declaration and values
struct  tablestruct Advance_vs_Map[4] =
{
{10,1000,2000},
{50,2000,1000},
{100,3000,500},
{255,5000,0000}
}

Now, on serial datastream ...  Fairly important for tuning
No checksums, CRC's, or "command codes."  Only a "go faster" command.
This is pretty simple.  The ECM starts at a "slow" baud rate.  Send it an address
( 8 bits) and it replies with the data at that address ( remember these have RAM
from
0x40 to 0xff).  The connector is under the hood.  Invert the signals, run through
a MAX-232 chip and then into the serial port on your laptop.  If the slow baud is
not fast enough for you, send it the proper data and it will kick into "fast
mode".

And for those tired of burning and erasing EPROMs, the eproms on this particular
board can be directly replaced with a AT28HC256  or the 28C64 eeprom chips.  For
those more ambitious, it is a 1 hour job to put a 32 pin PLCC flash chip on these
( 29F010 type ore quivanent).

so where are others with these ?

Chad


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