Arduino standalone, randomly crashing

Hello, I've got a very strange problem with my arduino stanalone built around the ATmega328p u-th in the QFN32 Package. I've got multiple decupling caps and I'm powering it from an LiPo Battery. I also did this Clock project with the ATmega328P U in the DIL28 package which works just fine.

So now to my strange problem: After I had soldered all the components to the Board and checked it for shorts I tryed to burn the Bootloader which worked fine but the problems started to appear as I had to do multiple trys to upload my code. Most of the time when I tryed to upload the code I just got a response from avrdude telling my stk500_getsync() x of x not in sync.

Also when the code is sucsessfully uploaded it just runs a few minutues and freezes or just dies. I resoldered the IC multiple times but it only works as long as the IC is warm. After a few minutues it just stops again. Some other really odd failures where that without doing anything to the Board some pins got very low resistance even thought they had a very high resistance 10 Minutues earlyer. When I reheated the Chip, the very low resistance of for example: the XTAL inputs (330Ohms) were gone but some other failure occurred. And there are no solderbriges over the IC's contacts!

I don't understand what is going on here and I'm very frustrated because I tryed nearly everything to get it working but without succsess.

I hope some one could help me please!

Post your schematic, and a close. in focus image of your PCB (Assembled) please.

Hi, thanks for your reply. Here is my Schematic and some Pictures of my board. Sorry for the bad image quality. I just do not have a better camera.

Ran out of Space :frowning:

Try to fuse to work from internal 8MHz oscillator. instead of crystall.

Is it possible to do this with ArduinoasISP?
I do not want to spend more money for that project and I do not want to wait for an proper ISP Programer to arrive.

yes it's possible. For example How to Change Fuse Bits of AVR Atmega328p - 8bit Microcontroller Using Arduino : 7 Steps - Instructables

Did you use liquid flux when soldering?

windoze_killa:
Did you use liquid flux when soldering?

I used Soldering Grease.

I assume you mean solder paste.

I used Solder Paste but I also used soldering grease. It's non liquid flux. It only gets liquid if it's gets warmed up.

**QUICK UPDATE: **

Replaced the microprocessor (ATmega328p), with a new one because I couldn't even burn the 8Mhz bootloader
Replaced the Ceramic Resonator
It still wasn't working. Still the same behaviour: as long as the Board is hot it works. When it's cooled down, I can't even upload a sketch.

Burned the Arduino 8MHz bootloader.
Still the same Issue!
Also I measured some pins while the Microprocessor and the resonator where removed so I can make sure that my Board hasn't got some problems.
Thanks for your responds

This statement: " I resoldered the IC multiple times but it only works as long as the IC is warm. After a few minutues it just stops again", leads me to suggest there is still flux under the QFP. Clean again with IPA and a tooth brush and thoroughly rinse with HOT flowing water. Blow dry with compressed air.

Paul

PS. The solder paste already has more than enough flux for soldering and that flux is water soluble so it can be washed off the board. That fact that you used "grease" means it is not water soluble and may be impossible to clean your board. Flux loves to get under your QFP.

I’m still waiting for the schematic!

Why are your decoupling capacitors so far from your processor, they should be within a few MM.

missdrew:
I'm still waiting for the schematic!

Why are your decoupling capacitors so far from your processor, they should be within a few MM.

Sorry that got lost somewhere.

Just a suggestion for future projects. Changes you page size to A3 so you can spread things out more. It makes it easier to read and modify. eg, C2 and C3, move them away fromm the micro, they look clostraphobic. U2 further away, That way you wouldn't have to use port connections to add the decoupling cap.

Also pay attention to the orientation of components. eg, H1, if it was rotated 90 degrees anti clock wise you could have had 5V going to the to instead of downwards.

Paul_KD7HB:
This statement: " I resoldered the IC multiple times but it only works as long as the IC is warm. After a few minutues it just stops again", leads me to suggest there is still flux under the QFP. Clean again with IPA and a tooth brush and thoroughly rinse with HOT flowing water. Blow dry with compressed air.

Paul

PS. The solder paste already has more than enough flux for soldering and that flux is water soluble so it can be washed off the board. That fact that you used "grease" means it is not water soluble and may be impossible to clean your board. Flux loves to get under your QFP.

Thanks for this idea. The compressed air did the trick.

pcbtea:
Thanks for this idea. The compressed air did the trick.

Good, but don’t think it is a cure-all. Compressed air generates static charges and it needs to be de-ionized.
Paul