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91  Forum 2005-2010 (read only) / News / Re: ProtoShield using "Household" Items for < $5US on: December 29, 2008, 09:39:29 pm
yeah, someone posted something similar on the instuctables site.  that approch makes sense to me.  go for it.

just for reference, I'll paste my instructables reply to "why not just use male headers?"

"a few reasons:

    * this board only has metal on the bottom, so soldering a standard header would be tough at best. I suppose you could flip the board over, but...
    * there's still that offset female header to deal with. a standard male header won't work because it's rigid and straight, and the holes don't line up.
    * I like the idea of all the raw materials being readily available. some huge percentage of Americans (90%+ I think) live within 5 miles of a Radio Shack. male headers can be harder to come by. (Note: I realize that not only Americans are interested in this instructable, I just live here, and don't have electronic store distribution information from other countries smiley-wink )

you do make a good point though. in one of my earlier attempts I used a flipped board, male connectors where they'd work, and wire for the 8 pins where they wouldn't. that definitely sped things up, but I figured I was already using the wire, why not go all the way."
92  Forum 2005-2010 (read only) / News / Re: ProtoShield using "Household" Items for < $5US on: December 29, 2008, 08:02:49 pm
I did a basic continuity test after everything was done, but that was more to test that I hadn't botched the soldering job.  (I really should have done that BEFORE epoxying, but oh well, at least now I can answer your question)

if there's any leakage it's minimal.  I'm with you that that could definitely impact things, especially on the analogread side.  if I get reports back that there's problems of this nature I'll find a more electrically inert epoxy (even regular glue might do,) and update the instructable accordingly.
93  Forum 2005-2010 (read only) / News / ProtoShield using "Household" Items for < $5US on: December 29, 2008, 01:54:15 pm
Hi everyone,

I just posted an Instructable detailing how to make a ProtoShield that accesses all the pins (yes, even the offset ones)  using stuff that's cheap and widely available.  have fun making tons of cheap shields for all your projects!
94  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Tuning the PID Library on: December 18, 2010, 04:06:56 pm
eecharlie, an autotuner would be a huge benefit to users of the library.  

if you publish it and it works (somewhat well) at the very least I'll include it in the PID front-end.

95  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Tuning the PID Library on: August 20, 2010, 05:55:48 am
The point is, sometimes you just have to go with what works.   smiley-wink

Absolutely, the trick is knowing when to throw in the towel on a pid-only solution.  It sounds like that's exactly what you did Coding Badly.

On several occasions I have gone to a customer site to fix a poorly performing PID loop and found a long set of pid overrides (Do this on startup BUT not if this, and also THIS, etc.) On most of those I was able to replace the entire thing with a more simple strategy as I suggested above.

But yeah, ultimately the goal is to make it work. Since generally the hobbyist is the only one who needs to really understand what's going on in the code, a little extra complexity is fine.  If you're going to share your code it might take a while to explain all the conditionals and why you chose the values that you did.

In general I try to keep things as elegant and simple as possible, as I've learned that minimizes future "why the heck is it doing THAT?!" moments.

96  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Tuning the PID Library on: August 19, 2010, 09:59:27 pm
Is this something I can use the bias for?  
I don't think you'd get good results with the FFBias.  that's designed for situations where you have a repeatable disturbance that you can measure in advance.  what I'd recommend trying is using the SetTunings(...) function to use more conservative tunings (smaller P_Param) at higher altitudes, or when you see the controller begin to act too aggressively.  that being said, I have no experience with high altitude aerodynamics, so I may not be understanding the dynamics involved

Can someone please explain what the heck the UNITS are on the PID parameters?
pfft.  just keep adjusting the numbers until something works. who cares about units?!  ...just kidding.
P_Param is %OutputSpan/%InputSpan (where % is calculated using the Input and Output Limits)
I_Param and D_Param are both seconds
97  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Tuning the PID Library on: August 01, 2010, 08:36:38 am
We'll just have to get you a new job so you can write some auto-tune software for the Arduino.

Having dealt with various auto-tuners over the years, I'm not sure I would want to write one, even if my employment agreement allowed it.   auto-tuners can be beat by a moderately informed human just about every time.

I hope this thread will turn into a tool for (moderately) informing people.
98  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Tuning the PID Library on: July 27, 2010, 12:54:47 pm
Also since this is a thread about PID tuning, let me throw up some suggestions for Trial and Error Parameter Adjustment.  If the math in the mbed method isn't working for you, use these rules of thumb to get the performance you want.

Parameters and what they do (sort of)
P_Param:  the bigger the number the harder the controller pushes.
I_Param:  the SMALLER the number (except for 0, which turns it off,)  the more quickly the controller reacts to load changes, but the greater the risk of oscillations.
D_Param: the bigger the number  the more the controller dampens oscillations (to the point where performance can be hindered)

These are rules of thumb and aren't exactly what's going on inside the controller, but they should help when deciding which number to change and in which direction.

And lastly, if the second you enable the controller the output goes in the wrong direction and pegs at 0 or 100%, you've got the sign of the P_Param wrong.  That is, if you've got a 3 in there, make it -3.
99  Forum 2005-2010 (read only) / Frequently-Asked Questions / Tuning the PID Library on: July 27, 2010, 12:21:51 pm
The guys over at ARM have ported the Arduino PID Library to work with their mbed platform.  I'm mentioning this on the Arduino board because as part of the port they did a really nice writeup on PID tuning.  Since the backend is the same, their procedure will work with the Arduino library as well.
100  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Best Way to Connect for High Current Applications? on: August 13, 2010, 01:53:07 pm
I just finished a triac project of my own, and I'm not sure I did a great job in this area.  I'd also be interested in hearing what people have to say.
101  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Multiple Shields on an Arduino? Complex Systems Q on: July 25, 2009, 07:13:06 am
When designing something of this magnitude, can you connect several of these functionality shields together to all be controlled under one arduino?

I'm not sure if you're asking if the arduino has enough IO to drive all those shields, or if it's physically possible to connect them all.

If it's an IO question, that would depend on the shields being used.  if you're wondering about physical connections, you can buy stacking headers that will let you stack as many shields as you like.  (

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