>>I am working on a project that requires temperature control
>>in a wood pellet fired BBQ grill. I would like to use the
>>PIC16C72A chip.

>These guys have a tutorial on PID which uses a BBQ controller as an 
>example...


I remember back in the very early days of the microprocessor era (when every 
company seemed to have an architecture of their own) there was an article in 
Electronics magazine (I think this eventually became EDN) where a guy 
described using a SC/MP micro to control the flue flap on his wood stove. He 
measured the exhaust temperature from the flue, and adjusted the flap to 
keep this constant. When it got to the point where the flap was fully open, 
and the temperature had fallen a preset amount, it rang an alarm, at which 
point he put more wood on the fire. Once the fire came good it would close 
the flap to stay inside the control loop again. At the time I thought it a 
neat project, but seemed to be a bit of a waste of a micro chip, to dedicate 
a whole chip to just this job.

Sort of thing one could do with a more modern chip running at very slow 
clock speed.

But coming back on topic, Microchip have a neat looking app note where they 
describe using an 18F chip, with a bunch of their own analogue chips to do 
cold junction compensation for a thermocouple, and have it doing 0.1C 
accuracy measurements over -100C to 1000C (assuming you have a thermocouple 
with suitable insulation for the upper range, most commercially available 
items don't seem to have insulation good for more than about 300C). Check 
out AN1306 at http://ww1.microchip.com/downloads/en/AppNotes/01306a.pdf
The principle should be applicable to the chip you propose to use.


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