PID and Arduino
 

Some of you have been using arduino for projects and I just picked up a Mega, BUT, I am a luddite when it comes to programming. When I went through DeVry electronics in the early 80s, I was interested in audio not computers so programming is hard for me to get my head around.

Therefore, the question, has anyone done any PID loops with the arduino? I want to make my heat pump controller or at worst control some pumps. Also, it seems they recommend 20ma max per pin for loads. Try getting a relay with that type of coil draw...uggg

I don't have any experience with PID loops. The concept doesn't seem too hard, but programming one sounds like it might be fairly complex.

I can help with your relay problem though:

For low current DC, you can use reed relays. They can typically handle switching loads of around 100mA.

The next step up is using a transistor of some sort. To get more gain you might need to use two transistors, or a transistor that switches a relay.

The easiest thing for switching AC power is a solid state relay. The arduino can switch them directly. I'm using one of these in my attic heat project to power the fans.

I usually use a DDC control that has 12 thermister inputs, 6 relay outputs a couple of 0-10vdc outputs as well. The company was bought and the price tripled. I was looking to see if the duino would support something like the old control and I thought to make a board with the relay options on it that could plug in like a shield does on the duino. It might be a challenge.....

Check THIS out. (maybe 80,000 links)

Best,

-AC

yes, Thanks, I am just getting into the Arduino world and i found it last night. Those crazy code guys.......

code guys
 

well if you're just getting into this, Arduino is a great way to go.

It has two ways of programming, a simple but somewhat limited way,
and a much more complex and capable way.

Also know that there are pre-written and pre-tested code libraries that you can use.

Also, it is common practice to post your project on the web, just like Daox did, with the code available to other people.

So, there are people all over the planet working with this stuff, and the code that is available is growing every day.

And, taking the PID example, PID can be used in very many ways. And with 80,000 projects (many of them will be bad Google hits), there is a very high likelihood that someone else tackled a project just like you want to do, and you don't have to re-invent the wheel.

-AC