Code Compatibility

ATmega48/88/168 is code compatible with ATmega48PB/88PB/168PB.

To ensure that code designed for ATmega48/88/168 executes on the ATmega48PB/88PB/168PB the user must remember to change the device and recompile the code.

A general rule of thumb is that reserved bits should be written to zero if accessed. Reserved I/O memory addresses should never be written.