68HC11s

[Roger Heflin]

On Wed, 2 Jun 1999, Bruce Plecan wrote:

> Would at some point in time it be worthwhile to replace a unknown gm 68HC
> with a known straight Motorola 68HCxx, and then rule that out as a
> variable?.
>   Or are the slight code differences mute?.
> Bruce
> 
> 
> 
The code differences (different locations of config registers, and
different defaults locations of stuff) would make things not work.
And I heard one of my professors (in college, he did sabiticals with
Delco and Motorola both) claim that all 68HC11 had in their mask
GM/Delco code that was disabled on normal commercial versions.
It looks like to me that on the later versions of the ECM's GM/Delco
got Motorola to produce versions that had all of the features they
required built in to simplity their job.   GM/Delco should not have
had too much torouble getting motorola to do that considering the
number of chips they were purchasing.   It also looks like those same
chips are sold to others pretty much unmodified.   Mine lnes up pretty
closely with a MC68HC11F1 and everything seems to like up right, ie
things that should be on A/D ports were, and I really did not find any
inconsitancies between the modesl.   If they are using a more basic
68HC11 chip the real question is how much extra ports were added and
were in the data space were they added.   The F1 variant seemed to
have pretty much everything needed except a PWM ouptut, and more than
8 A/D inputs.   I noticed that that later version had a PWM built in.
Also on mine the injector control was using the timer interrupt
registers, mine being a batch fire where each side is fired
independtly means mine needs two timer interrupt registers and that
was what is was using , I don't know how a SFI setup would do things.
I was pretty lucky one mine that there appeared to be a very limited
amount of external hardware, so I was able to look thorugh the
different register configs to find one that seemed to match.

			Roger