Re: CM11A hangup: Any better products?

[ddl@danlan.*com (Dan Lanciani)]

In article <aMHPe.8969$A%1.2187@xxxxxxxxxxxxxxxxxxxxxxxxxx>, notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx (Joerg) writes:
| Hello Dan,
|
| > | > The CM11a does employ a resonator for the PIC's clock, but it uses a
| > | > separate free-running LC oscillator to generate the 120kHz carrier. ...
| > |
| > | Interesting. I wonder why they did that.
| >
| > My theory is that the implementors of the CM11a were familiar with the
| > free-running oscillator design used in the TW523 and decided to adapt
| > it.  It was a proven circuit used in other X10 products as well.
|
| That could very well be but it would be pretty sad. Engineers are
| supposed to embrace new concepts when something can be realized at less
| cost.

Of course, they might have done the analysis and decided that this solution
_was_ the most cost effective.  Typically X10 does a pretty good job of
"value engineering" in spite of what its competitors sometimes claim.

| > | They could have saved the cost
| > | for the extra LC if they used a timer on the PIC to generate the 120kHz.
| >
| > Does the 16C58 have the capability to route a timer to an output pin?  When
| > I wrote the enhanced version of my replacement firmware for the RR501 I used
| > a timer, but I had to swap some pins around to I could send it out via the
| > PWM block of the 16F628 (not doing actual PWM, of course).
|
| Frankly, I don't know the PIC series much. But it would surprise me if
| it wasn't possible. Pin swaps may be needed. Timer-based outputs are
| pretty easy on most uC like the MSP430 series even though they often do
| not have a dedicated PWM block.

As far as I can tell, there is no obvious way to route the 16C58's TMR0
(the only one it has) to an output pin.  I don't think this function is
typically available on 16x PICs.  I was able to do it only by using that
PWM block in basically a pass-through mode, and a PIC with a PWM block may
not have been available (or cost effective) when the CM11a was designed.

				Dan Lanciani
				ddl@danlan.*com