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 peggy 2.1 issues
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By: Anonymous: Willy () on Monday, April 27 2009 @ 07:18 PM PDT  
Anonymous: Willy

I've been meaning to post a similar? problem that I haven't been able to solve. I have a Peggy2 running with a atmega328. I have the entire board filled in with LEDs - all white with a blue border on the top and bottom. I know at one point after I finished it, it was working fine (I tested it after install each row of LEDs) - the minimal program was lighting up perfect. Since then I've download and installed many of the other demo programs.

The first time that I noticed a problem was after running the invaders program for more than 10 minutes. I'd come back up to the room and it was flashing - I think basically doing a reset. I noticed that if I turned it off and on right away, it would start flashing again but if I let it sit for a few minutes, then it would start up fine again. With my limited electronic experience, my first thought was that I might be a capacitor problem.

Since then I haven't been able to get Minimal to work or Getpoint but other programs like Line, Clock, Gray test and Qix seem to work fine. I've check all my solder connections and can't see a solder bridge.

Previous to this, I finished Meggy Jr and that seems to be working just fine.


Any assistance or suggestions you could provide would be greatly appreciated.


Thanks!






       
   
By: willy (offline) on Monday, April 27 2009 @ 08:08 PM PDT  
willy

Meant to say that 16level seems to work okay (but still flashes after a while) but GrayTest doesn't work at all. Since my last post, I have tried reseating all of the chips - didn't see any bent pins. I also reheated the connections for electrolytic capactior and the two small ones near it just to make sure the connection was a good one.




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By: Windell (offline) on Monday, April 27 2009 @ 08:46 PM PDT  
Windell

Willy,
What's your power source? Is this under batteries or a DC adapter or both?


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By: willy (offline) on Monday, April 27 2009 @ 09:00 PM PDT  
willy

Sorry about that. I've been running exclusively off the 5V power supply that came with Peggy. I didn't bother installing the battery holder because I found a perfect spot on the wall for it and it is directly above an outlet. By the way, I've running cube now for over a half hour and no flashes so it definitely seems to be related to how many led's are in use. I've also used life and haven't noticed it flashing either. Bugs me that minimal isn't working as I know for sure it was after I finished putting Peggy together.



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By: willy (offline) on Monday, April 27 2009 @ 10:24 PM PDT  
willy

Sorry about that. I've been running exclusively off the 5V power supply that came with Peggy. I didn't bother installing the battery holder because I found a perfect spot on the wall for it and it is directly above an outlet. By the way, I've running cube now for over a half hour and no flashes so it definitely seems to be related to how many led's are in use. I've also used life and haven't noticed it flashing either. Bugs me that minimal isn't working as I know for sure it was after I finished putting Peggy together.



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By: willy (offline) on Monday, April 27 2009 @ 10:37 PM PDT  
willy

Update:

Good news! I turned the pots down (about three counter-clockwise rotations) and the flickering on Invader and 16levels of gray stopped. It's odd that they didn't start flickering but started after a while?? These programs behaving properly now. I was perplexed about the minimal and Getpoint not working so I decided to swap out the 328 for a 168 that I was originally using (forgot that I had switched). All the programs seem to be working fine now. I am using Arduino version 0015 to do my programming. For the 168, I am using the board option "Arduino Diecimila or Duemilanove w/Atmega168. When I was programming for the 328, I used Arduino Duemilonove w/ATmega328. I must be choosing the wrong board for the 328 but I didn't see any other option for the 328.


Thanks again for all your help!!!


Willy


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By: Windell (offline) on Tuesday, April 28 2009 @ 11:46 AM PDT  
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Okay, I've been able to reproduce the problem-- or part of it at least-- under certain circumstances. With a fully loaded Peggy 2.1, brightness at max, on the standard 5V power supply, using "peggy2_minimal," one of our boards freezes in reset, with one or two rows fully bright and essentially no response. I did not have any trouble reprogramming it under these conditions, but it was not interested in displaying that program. Other programs that don't have as many LEDs on at once seemed to be working just fine.

What I found was that adding a 10 uF capacitor across the power supply (vcc - gnd) at the power supply pins on the left side of the microcontroller fixed the problem-- the peggy2_minimal program seems to run fine and there was not any difficulty in reprogramming it or displaying other programs.

I suspect that desoldering and moving the 1000 uF cap to that side of the board would also fix the problem, which appears to be one of very brief voltage dropouts below the brownout threshold of the AVR, when running at high current. There may be other solutions as well.

Barring other suggestions, we'll adding an extra cap to our kits soon. In the mean time, if anyone with a Peggy 2.1 kit is experiencing problems like this, please contact us through the Evil Mad Science contact form, and we can send you a cap to add to your board.


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By: willy (offline) on Tuesday, April 28 2009 @ 12:42 PM PDT  
willy

I'm fine with lowering the brightness - I can barely tell the difference between what it looks like now and what it was before. I'm confused why the 328 seems to cause problems with minimal but not the 168. Do you think that adding the capacitor would allow my 328 to work as well. The 328 did seem to program okay but it just wouldn't run minimal. When I replaced it with the 168 then minimal worked fine. I'd love to have the extra memory but frankly I'm just happy that everything is working again!

Thanks for all your help and suggestions!!


Willy


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By: Windell (offline) on Tuesday, April 28 2009 @ 01:00 PM PDT  
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I'm not sure what the issue is with '328, so I don't know if it would or would not be fixed by the cap. I suggest that you do request a cap from us, so that your board will *at least* work properly with the 168. Smile


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By: willy (offline) on Tuesday, April 28 2009 @ 03:04 PM PDT  
willy

I will request the cap and try it out but actually since turning down the brightness with the pots, everything is working fine with the 168. I am still having a problem running minimal from the 328 (I don't know if the upload isn't working or if its just not running properly). I swap out the 328 and put in the168, everything is good, I put the 328 back in and it still won't run minimal but does seem to run other software okay. I'll try out the cap and see if that fixes the issue with the 328. I was just wondering if this problem made any sense given the differences between the two chips.



Willy Smile


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By: lagomorph (offline) on Saturday, May 02 2009 @ 01:41 PM PDT  
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I've placed a 10uF cap across VCC and GND on the 168 as suggested by Windell and my board seems to work fine. I also have no trouble programming it with that cap in place.


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By: willy (offline) on Saturday, May 02 2009 @ 01:53 PM PDT  
willy

I'm going to try that as soon as the 10uf cap arrives - I ordered one through the contact form. Have you had any luck with the 328? I'm going to try again but I was having problems getting it to run the programs that use more LED's even with the brightness turned down. The 168 is working great now even without the cap.


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By: lagomorph (offline) on Saturday, May 02 2009 @ 02:20 PM PDT  
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I don't have a 328 unfortunately. Frown


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By: Anonymous: SUzB () on Monday, May 11 2009 @ 07:10 AM PDT  
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Quote by: Windell

The behavior that you are seeing would all be explained by the board going into reset-- where the board goes black except for one or two lines (which go deadly bright) for a few seconds.

This certainly seems exactly like what I've seen on boards with a couple of bad solder joints-- it could also be caused by having the AVR microcontroller not fully seated in the socket. The board, when full of LEDs, is *very* heavy and tends to flex more than other circuit boards, which can make it a little more sensitive to iffy joints.

So... Make sure that the AVR is *fully* and securely in the socket, with no pins accidentally bent on the way in. Check to see if the same behavior occurs when the board is sitting on its own on a flat surface, or more often when you touch it-- that might give a hint about what's going on.



I guess we have an issue on solder joints. But I am not able to check them.

My son (11 years) did the solding and I am not very good at this. How can we identify iffy joints. Would it help to sold all of them again?






       
   
By: Windell (offline) on Monday, May 11 2009 @ 09:43 AM PDT  
Windell

SUzB: Can you describe what the exact problem is, in some detail? If it's a soldering issue, we might be able to suggest where to look, and if it's otherwise, we might be able to suggest a different solution.

Cheers,
-Windell


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