Tim Wescott wrote:
On Tue, 08 Dec 2009 21:08:33 -0600, RogerN wrote:

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"RogerN" fired this volley in
m:

Perhaps as part of the program you could have it record how much
adjust time of the curtains accumulated over a day. Try to tune the
algorithm for best temperature control with minimal winch run time.


Roger, a decent PID algorithm accommodates changes in conditions, and
"learns" the lead/lag characteristics of the system. Most of the even
most-basic PID controllers (ready made) have that capability.

LLoyd
It's been a while since I messed with my Basic Stamp but IIRC they used
8 bit integer math. My Basic Stamp 1 had only about 16 bytes ram, I'm
not sure that would do a PID control, maybe. I think the BS2 has about
twice that amount of ram. I'm not to great at working with integer
math, especially 8 bit.

RogerN

Ouch. That's pretty restrictive. You'd need at least 16 bits to do PID
in this sort of thing, and mo is better.



'splain why?

The timing is closer to hours than milliseconds.
A real time interrupt (external 555?) for the long delay?

8 bits of temperature is 256 value spread.

The AtoD function can be external hardware, or an external mux if
an internal AtoD is there. One bit to select from two sources,
two bits for 4.

Motor control is one bit for direction, one for Go.
An eight bit count for run time to position the vent.



Too much bloatware in the world today.

What we need are more Assembly Programmers!