I got some chips in from Digi-Key, which were giving me the wrong signature byte. Here's what avrdude said about them:
avrdude: Device signature = 0x1e9514 avrdude: Expected signature for ATMEGA328P is 1E 95 0F Double check chip, or use -F to override this check.
I sent a query about this to Digi-key. Their response is confusing me a bit, hoping someone could clarify.
The order was for 4 ATMega328p processors - Digi-key part #ATMEGA328-PU-ND.
The response from Digi-key was
"The ATMEGA328-PU-ND is NOT a ATMEGA328P it's a ATMEGA328 so the signature should NOT
Aside from the fact that what I ordered was a 328p and they seem to be telling me they sent a 328, I can't find a definitive statement of what the difference between -P and -PU is. Clarification would be welcome.