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IWDG with hardware watchdog feature

Question asked by Arjun Oberai on Jan 17, 2018

I am getting problem while making the #IWDG work with the hardware watchdog feature in #STM32F103RB. I am doing this so that the watchdog is automatically enabled at power-on. 

To make the hardware option work an option byte is written to the flash memory. 

 Looking at the Option byte programming(section 2.3.5) of the Flash Programming manual attached. I follow the sequence 

  • Checking that no Flash memory operation is ongoing by checking the BSY bit in the
    FLASH_SR register.
  • Unlocking the OPTWRE bit in the FLASH_CR register.
  • Setting the OPTPG bit in the FLASH_CR register.
  • Write the data (half-word) to the desired address[Where to write, I know the address but which register?]
    Looking at section 2.5 I want to clear the bit 16 of the flash memory that has address 0x1FFF F800. 
    What I am not sure about is that where can I write this (bit 16: WDG_SW) value so that the MCU knows that watchdog needs to be hardware and not software. 

    Does there need to be a pointer pointing to the address?
    How to Write the Half Word?


Thank You in advance,