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!