About STM32G474 option production value?

[fastfret]

My target device is STM32G474VET6. I checked my empty device that the values are the same with "ST production value" from user manual. (Please see the screenshot)

After flash programming on this chip(have done erase and program, no options), I read device again. I checked the reserved bits become to different with "ST production value".

I know the difference are about reserved data. But my end user concern about why the options are not default when finish programming.

By the way, I try to program options back "ST production value" is not work.

Is this situation right?

And I did not program options, but options still become to not default.

[Igor Cesko · Accepted solution]

Hi YLiao.3,

The reserved bits are usually unused and programmer puts those unused values to "1". This is done due to erase of option bytes (erase is all bits in "1") and then masking given option bits and programming them to given values.

If you want to put those reserved option bits back to "0" then is necessary to do this through different programmer or through firmware routine.

But there is no difference in functionality - this is just erase and program side effect.

Regards

Igor