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Wes wrote:
> Ralph, Thanks for reigning in the rabbit chase!
>
> As the originator of this thread I'd like to respond to the 'why'...
>
> I keep running out of ports on my creations. I see 5 or 6 as a practical limit. My criteria for a
> solution:
>
> 1. Entirely compliant with RCX firmware.
> 2. Clean programmability. My initial idea: control is accomplished by setting the power level of a
> port to select which device, and by setting the second port for actual device performance (on/off,
> fwd/rev, pwr level). This means it would be usable by the RIS software.
> 3. Reasonable cost (In my mind this means < $50).
> 4. Leave at least 1 port for normal, direct RCX control.
>
> The directions this thread has taken are not attaining this goal. Instead of blue-sky ideas about the
> theoretical possibilities I'd like to see possibilities/critisisms towards an attainable project. Am I
> way off base on the ability to create a simple circuit that measures various PWM to enable a set of
> ports? If this is am expensive undertaking then say so now so more time isn't wasted on this topic.
Measuring PWM is not difficult, but it would involve a micro (PIC12C508 anyone?) dedicated
to the task and then you would have to get it to drive the RCX, which means motor drivers, etc.
If you are willing to spend $50 and LOTS of time, then why not just buy a second RCX and get
them working together?
I've said this often enough (and I almost beleive it myself) "Don't reinvent the wheel!"
You'll spend way more than that in time getting other kludges to work.
If you search previous posts in this group, you will find solutions such as polarity switches,
extra relays, etc to drive more than 3 outputs.
Nuff said...
Cheers,
Ralph Hempel - P.Eng
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