I have a bespoke board that looks to the outside world like some Uno clones (it uses the FT232RL FTDI chip), but it uses the Atmega328PB rather than the Atmega328P. I amended the expected signature for the Atmega328P in avrdude.conf to match the signature of the Atmega328PB.
Results are as follows
I can burn the Atmega328P bootloader through the interface using the Arduino.org ISP and the latest IDE. This appears to go through without error.
Similarly, I can upload a simple sketch using the "Upload using Programmer" option
This sketch returns Serial data correctly to the Serial monitor
BUT I cannot upload sketches direct from the IDE to the board in the normal way. I get "stk500_getsync()..." errors. I have tried several suggestions for fuse settings found on the web, and they result in different response codes
I don't need the extra facilities in the Atmega328PB - happy to have it behave as an Atmega328P
Any suggestions for fixing the problem?