[Color Computer] Re: [Coco] Motorheads and the CoCo...

Frank Pittel fwp at deepthought.com
Wed Jun 15 22:49:12 EDT 2005

The 68hc11 was designed for controling engines. For many a year every
car made in the US had a 68hc11 running the engine.


On Thu, Jun 16, 2005 at 12:09:16AM -0000, James Diffendaffer wrote:
> I'm pretty certain the 68HC11 has been used for this purpose in the
> past but I'm not sure what clock speed.  Probably a little faster than
> the 09s that are out there.  For some reason I seem to remember it
> being over 10MHz (16?) but I don't even know if that chip is available
> in that speed.
> I think manufacturers have long since moved on to chips like the 52
> series Coldfire CPUs and various RISC chips.  The ignition and fuel
> mapping is much more complex than it used to be and that requires
> greater speed and a larger address buss to handle the data.
> --- In ColorComputer at yahoogroups.com, "George Ramsower" <yahoo at d...>
> wrote:
> >  Taxing the coco is a major concern with an SEFI system. So in my
> plans, the coco does not actually do all the work. It only handles
> engine management, while a separate board will actually do all the
> actual work of firing injectors(PWM), adjusting the idle air bleed
> stepper and  controlling spark advance.
> >  The coco will monitor MAP, MAF, O2 sensor, coolant temp, air temp,
> RPM and all the other required information to make the commands to the
> controller. 
> > 
> >  My thinking is that if the coco fails, crashes or otherwise is
> rendered inoperable, the controller will still function and run the
> engine in the "Limp Home Mode".
> > 
> >  The rough drawings and parts list for the controller is not simple
> in any way. It is totally constructed using standard old TTL chips
> mostly, some other chips that do stuff like the PWM for the injectors,
> up/down counters and a lot of 555 timers. It will have 64K of static
> RAM also for mapping the RPM range and TPOS and MAP. 
> >   The mapped static RAM is preprogrammed by the coco after initial
> power is applied to the controller. 
> > 
> >   Too much to tell about this in one email.
> > 
> >   I believe that the coco is fully capable of handling the
> management end of this system, even if it was written in RS-Basic..
> but I'll use OS-9 because I like it.
> > 
> >  Since the coco will have to load up software to do this, the
> controller will work fine during initial startup of the engine. Once
> the coco is online with things, it will make any necessary adjustment
> to the controller while the vehicle is in operation.
> >  The reason I decided to use the old reliable 74XX and 74xxx, some
> 54x stuff to is speed and reliability. TTL is equal to about five
> million instruction per second. More than is necessary to control an
> engine at 6000 RPM(one hundred revs/second). Since 4-cycle engine
> timing is based on the camshaft in SEFI, we now are dealing with only
> fifty turns/sec.
> >  Okay, some of you have engines that are good to 7500 RPM. This is
> still only  62.5 turns/sec on the cam.
> >  
> >  Surely this could be done easily with something like a 68hc11 or
> some of the other magnificent microcontroller chips, but I'm crazy
> about the old TTL stuff and using a coco to control them.
> Brought to you by the 6809, the 6803 and their cousins! 
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