>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>Sent: 28 April 2006 20:07
>To: Microcontroller discussion list - Public.
>Subject: [OT] PID source code
>
>
>I'm hoping someone can shed some light on code I'm doing for work.
>
>We make temperature controllers, and I'm doing the code for a 
>new board.
>
>However, our "standard" PID code looks like nothing I've ever 
>seen before.
>
>I've googled for PID code, and haven't found anything that 
>looks like our algorithm.  And, of course, I can't let someone 
>else see our "trade secret" code.
>
>The comments say that it's a "textbook PID algorithm" with 
>"rate and reset in seconds".  But it never says which 
>textbook, and the original programmer (1994) is long gone...
>
>Can anyone point me to PID source code so that I could figure 
>out what is going on?  Anything that looks like the standard:
>   error = value - set_value;
>   p = kp * error;
>   i += ki * error;
>   d = kd * (error - last_error);
>   pid = p + i + d;
>need not apply.


There are several variants on the classic PID, the above is the "parallel" algorithm.  There is also a "series" and the "Ideal"

http://www.expertune.com/artCE87.html should help you decide which one you have!

Regards

Mike

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