I recently bought some ATmega128A chips on eBay from China (a previously trusted supplier called H_quality). I can't get any life out of them at all. I thought maybe they were fake chips but I've tested that all the ground pins are joined together inside the IC and the same for the positive supply pins. No connection between these pins and any other pin (just checking they weren't all shorted inside). If they were fake chips I would expect all the pins to be shorted or disconnected. Hmmm.
Having scoured both AVR Freaks and the internet in general I've come across various posts where people have mixed up the MISO and MOSI pins as this chip for some reason uses different pins, PDO and PDI, for serial programming. I've triple checked these connections are correct, supplied 5V to all the positive pins including AVcc, 0 volts to all the ground pins. Programmer reset signal goes to to reset pin 20 and SCK to pin 11. Even though I think these ICs are supposed to use the internal oscillator I've put a crystal and capacitors just in case it needs them. Nothing. I mean, AVRDude says "target does not respond".
I can't see any reason why the fuse bytes could be wrong because I haven't touched them as I can't even get the ICs to respond.
Having worked on this for several days on and off I have now put these ICs and the carrier PCBs into a box marked "faulty". I've got plenty of other AVR chips which work fine (not ATM128's tho), but it's just annoying - I would report these as faulty to the supplier if I could be confident that I hadn't missed anything.
Has anybody got any suggestions as to any other mistakes I could have made?