Disabling IWDG In Standby

[TWood.4]

I'm using a WB55 with IWDG enabled. 

I want to disable The IWDG when the device is in Standby mode. 

I have cleared the IWDGSTDBY bit using STM32CubeProgrammer, but I still get resets from the IWDG.

What am I doing wrong?

[Issamos]

Hello @TWood.4 

I think you should to write 0 to the IWDG_STDBY bit of the register Flash memory option register (FLASH_OPTR) to freeze the IWDG counter in Standby mode. And then write 1 to the nRST_STDBY bit of the register Flash memory option register (FLASH_OPTR) to stop resetting during Standby mode.

Best regards.

II

[TWood.4]

Those are the settings I currently have.

[TWood.4]

I have tried both STOP and STANDBY modes with the IWDGSTOP and IWDG_STDBY bits cleared in the flash option bytes register. Reading back the register at 0x1FFF8000 gives 0x39F9F1AA - which confirms that both bits are cleared. (Table 9 from WB55 reference Manual shown below)

I also explicitly clear the DBG_SLEEP, DBG_STOP and DBG_STANDBY bits in DBGMCU->CR

I'm running out of ideas here.

Any suggestions?

[TWood.4 · Accepted solution]

Ah OK. RM0434 Rev 12 (WB55 Reference Manual) Says on P164 : 

Independent watchdog (IWDG): the IWDG is started by writing to its Key register or by
hardware option. Once started it cannot be stopped except by a Reset.