I wish to implement a digital PID controller for a heater. I have searched a lot on the web but did not understand the algorithm completely. Can the algorithm be written in assembly? What micro controller can I use? Can someone explain me the digital PID algorithm too?

 

The following link is from the Microchip website, a Heater DIY project with PIC. A short description is in the readme file.
http://www.microchipc.com/sourcecode/PIC_Hi-Tech_C_Mike_Pearces_heater_project.zip

source: (http://www.microchipc.com/sourcecode/#heater)
Have fun.

 

Here's some more info on PID. This is a good writeup that helped me learn how PID works. I keep a prinout of it in my top desk drawer and refer back to it occasionally.

The sucky thing about PID is tuning it. Especially when things take a long time to change, like the heat in a big heater. This is why commercially available heater controllers have built-in autotune features.

I remember running across some PID heater controller code for Arduino a while back; it was simple, no more than 10 lines long IIRC. I suspect you will find that the PID program writing will be easier and quicker than finding the proper P, I, and D parameters that work with your heater.

 

How are you controlling the heater? Just ON/OFF or a full proportional control?

If it's just ON/OFF you may be best served with just a setpoint and some hysteresis, ala 50° turn OFF, 48° turn back ON.

 

Here is a writeup that really helped me gain a better understanding of PID. To read the subsequent pages you can go to the next page by clicking on the link at the top of the page.

hgmjr

 

Thanks all. ErnieM, it is a PID, sir.

 

I understood the P, I and D fucntions. Can anyone explain me the algorithm and how I can implement it in assembly language

 

I understood the P, I and D fucntions. Can anyone explain me the algorithm and how I can implement it in assembly language

did you read all 7 pages of HGMJR's link? it explains everything. very good link. I printed it out to put with my other writeup. I think you should consider something other than assembly.