How uncheck Option byte ?

[Peko]

I used STM32G070. According to the reference manual RM0454 rev2, it does not exist in this procesor Option byte IRHEN (in User Configuration). But the program allows you to set it.

I did it, the processor stopped working, and no Option byte can now be written.

How fix it ?

Peter

[TDK]

Might try to connect in "Mode: Under reset".

[Peko]

Hello,

I tried it. It didn't help.

Could the processor fail by writing a Uption byte (IRHEN) that does not exist in the processor ?

Peter

[Andreas Bolsch]

I don't think your problem is IRHEN. The die of G070 and G071 is identical, the G070 devices may have failed some of the (stricter) tests, so some of the fuctionality not (officially) present in the G070 may out of spec (for G071) or even defective. E.g. on a G030 it's possible to toggle IRHEN without any problem, device operates normally even after power on reset, and debugger connects seamlessly regardless of IRHEN setting.

BTW: How does (if at all) your programmer identify the device? As G070 or G071? How could it distinguish these two? The only difference I could find between a G070 and G071 is that on (my) G070s some digits of the unique id are not valid BCD digits.

Maybe external circuit on NRST pin gets into the way (cap way too large)?

[Peko]

Hello,

Identify the device is bellow:

If I want to write something, it will appear:

There's no capacitor on pine NRST.

On NRST is high level 3,3V, but there were short impulses at 0V. They weren't there before.

IRHEN Checked: Internal resets drives NRST pin low until it is seen as low level.

Can the processor generate an internal reset for some reason?

Unfortunately, you can neither preprogram nor erase the program memory.

Peter

[Andreas Bolsch]

First: According to the first screenshot, your programmer can't tell the difference between G070 and G071 either ..

Second: If you see *regular* pulses on NRST this might indicate you've accidentally activated automatic start of one of the watchdogs.

These settings are in the very same option word ...

If yes, it might be a bit tricky to get access again: The programmer/debugger must assert NRST and keep it asserted, set DBG_IWDG_STOP and DBG_WWDG_STOP in DBG_APB_FZ1 register while in reset, halt the core immediately when releasing reset and reprogram the

option bits without core intervention. Don't know whether that's available in STM32CubeProgrammer, probably yes, but how to do this I don't know.