Ds1820 -> pid -> pwm

[malc-c]

@ malc-c , if possible put the code here as you had mension. I would appreciate.

To be honest you could use the code attached to my first post in the thermostat thread http://www.picbasic.co.uk/forum/showthread.php?t=12712
You would need to build / breadboard your hardware to match that used in the included hardware file.

@ HenrikOlsson, I'm reading and trying to understand your PID routine, i will post some questions soon about it, i have some questions!!
The Heater resistor that i have is 220V AC, i think it's better to do, like malc-c did, with a Solid State Relay, and low speed PWM.

I've not tried it, but I would of thought that it would be kinder on the resistive element of the aquarirm heater, especially as with it immersed in water the heater has less chance to cool as a similar element would in air. A SSR is the way to go - bit costly, but a lot safer

@ malc-c Again. I see your video, and i think the result its really great. If you change the Kp, Ki, Kd, variables, do you see any change to the process? Like, more slow/ fast to achive the SetPoint, for instance?

Thanks once again for everything.
Hope you can understand my english, sorry for all the errors!

From memory, changing the values altered things like the amount of over-shoot of the set point, the range at which the output started pulsing, and the length of pulse. The advantage with the code that Darrel and Henrick had put together was that using a serial cable and Hyperterm I was able to change the values via the PC and see what effect it had on my test rig which comprised of a heater in a wooden box with the sensor 6" below a ceramic heater. Over several weeks the values were adjusted and tuned until the temperature set point either maintained or was within half a degree either side (as you can see by the video - in the real environment it's almost spot on)