I now very little about designing PCB's. Is putting the crystal and caps inside the socket a bad design?
Siting the low impedance Xtal pin right next to RX0 on the 1284 wasn't very bright was it?
So, either I have a good pcb layout, or else the latest chips are less prone to glitching.
Well, I've not taken any special precautions on my first version prototype PCB layout, so when they arrive I'll check them with both fuse settings and the exact same 1284P I currently have sitting on a breadboard.I know this chip wouldn't upload via serial until I either added the 10k series resistor in RX0 or altered the fuse settings. If I repeat that on the PCB then it will also show if the problem manifests more profoundly when on a breadboard.
BTW, what is the data code on your problem chips? Also, did using the full-swing oscillatorfuse setting fix the upload problem, without using the RC filter?