hi! i must do a program whit hc11 that control the temperature with a 
sensor lm34 and compare this value to a value of a potentiometer. if 
the temperature value is up to potentiometer value power a fan wheel, 
if it's down power a panel heating. any person know how i can do that? 
it's my first project... thaks
	

 
In a message dated 2/10/06 7:59:54 A.M. Eastern Standard Time,  
fra_averna@fra_... writes:

hi! i  must do a program whit hc11 that control the temperature with a 
sensor  lm34 and compare this value to a value of a potentiometer. if 
the  temperature value is up to potentiometer value power a fan wheel, 
if it's  down power a panel heating. any person know how i can do that? 
it's my  first project... thaks
	=======================================
You need to write several small simple programs that do just one  simple 
thing.... first program: flash an led, second program: init the serial  port and 
send one char over and over,  next program receive a char  from the serial 
port. Third program: read the a/d and output the raw value  fourth program: read 
a/d, convert value to degrees and output it, maybe turn on  and off outputs, 
and you're done!
	[Non-text portions of this message have been removed]
	

On Feb 10, 2006, at 6:59 AM, fra_averna wrote:

> hi! i must do a program whit hc11 that control the temperature with a
> sensor lm34 and compare this value to a value of a potentiometer. if
> the temperature value is up to potentiometer value power a fan wheel,
> if it's down power a panel heating. any person know how i can do that?

Yes. Most everyone here knows how to do that.

You read the LM34 (probably with the A/D converter, but it might be  
on the SPI bus, I'm too lazy to look it up, same as you), then read  
the pot on the A/D. Adjust the scale of the values you have read so  
that the temperature range you are interested in  corresponds with  
the range of the pot inputs. Subtract the adjusted values and if  
negative turn the fan on or off, if positive turn the fan off or on.

If the LM34 is analog then you'd be better off doing this task in  
hardware without an expensive HC11 CPU. OTOH it sounds like a class  
assignment so the point is for you to learn something rather than to  
create something practical. Most instructors are smart enough to  
subscribe to lists such as this silently watching for their students  
to appear with their assignments.

> it's my first project... thaks

Start by doing research, rather than asking others to do it for you.  
There are examples from Motorola/Freescale which do exactly what you  
are asking. There is a .doc file in the Files section here on  
building a temperature sensor.
	--
David Kelly N4HHE, dkelly@dkel...
========================================================================
Whom computers would destroy, they must first drive mad.
	

> You read the LM34 (probably with the A/D converter, but it might be  
> on the SPI bus, I'm too lazy to look it up, same as you), then read  
> the pot on the A/D. Adjust the scale of the values you have read so  
> that the temperature range you are interested in  corresponds with  
> the range of the pot inputs. Subtract the adjusted values and if  
> negative turn the fan on or off, if positive turn the fan off or on.

In a real world application, don't forget some hysteresis.

-- 
Michal Konieczny
mk@mk@....

thanks to all