Hello,
You actually need to program the location NVOPT in flash memory. Whenever a reset occurs, this value is automatically written to FOPT. If your programming tool is capable of separately programming NVOPT, this method can be used. However, this register can alternatively be cleared as part of the normal MCU flash programming procedure.
If the latter method is used, this is one less process that can potentially be forgotten during production.
If using the internal reference oscillator, calibration of the trim value is another process required during programming. Your code might include a check that this has been done, and to provide some sort of external error indication during production testing, if forgotten.
Regards,
Mac
