Re: [oopic] Re: Providing a clock/time to the PIC

On Apr 1, 2008, at 4:37 AM, minghui1984 wrote:

> Thanks all for the replies. More stuff learnt with every post. I just
> realised that oopic does not support double or float numbers? hmm
> this is because my application deals with controlling a stepper motor
> to move a solar tracker, not quite the usual applications that ppl
> use the oopic for. So i didn't realised when i ordered, how would i
> store a values from the calculations and calculate inverse. One more
> problem is i realised that only single step movement is possible for
> the stepper function. >.<
>
> Guess i have to make do, the oopic simple interfacing allows me to do
> the prototype that demostrates my solar tracking. Hmm perhaps i would
> list it as future improvement.

Why not just change from open-loop (time-of-day) to closed loop
tracking? When the sun goes down drive your tracker back to its
easternmost position. When the sun comes up, use a pair of light
sensors separated by a vertical baffle (parallel to the polar axis on
your tracker) with a light sensor on either side. If the panel is not
facing the sun, the baffle will shade one sensor or the other. Use
that do drive your tracking motor one way or the other until both
sensors see the same light level. Now you won't need to know the time
of day and your tracker will work just fine based on sun position.

Here is a bit of a diagram. Use a fixed-width font to view:

SSS

|
|
|
s | s
-------
P

SSS = sun
s = light sensor
P = polar axis (coming out of the screen toward you)

--

Brian Lloyd Granite Bay Montessori
brian AT gbmontessori DOT com 9330 Sierra College Blvd.
+1.916.367.2131 (voice) Roseville, CA 95661, USA

http://www.gbmontessori.com

I fly because it releases my mind from the tyranny of petty things . . .
— Antoine de Saint-Exupéry

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