ALDL info

[Brian Hayes]

I just got out some logic analyzer traces from my 86 Chev Cavalier - 4
cyl.  This uses the 160 baud C3 - I assume.  Is it possible that there
are only 8 bytes of data??? (plus the header).  The pattern seems to
repeat every 81 bits ((8 data bytes + header byte) * 9 bits/byte).  This
is the data I get:

Engine off - key on
Byte Hex  dec
1    80   128
2    00     0
3    00     0
4    00     0
5    C9   201
6    00     0
7    76   118
8    00     0


Engine running - idle
Byte Hex        dec
1    80 or 84   128 or 132
2    2A          42
3    00           0	MPH??
4    2B          43
5    B0         176
6    2A          42
7    92         146
8    2A          42


Byte 5 tends to decrease as the engine warms up (IACV??).

Bytes 2,4,6,8 always seem to be about the same.

The 9 1's are pretty easy to pick out in the header.

Any thoughts or ideas would be greatly appreciated.

...The next step is to hook it back up and start pulling some wires!!