| KEY | Key value (write only, read 0x0000)
These bits can be used for several functions, depending upon the value written by the application:
- 0xAAAA: reloads the RL[11:0] value into the IWDCNT down-counter (watchdog refresh), and write-protects registers. This value must be written by software at regular intervals, otherwise the watchdog generates a reset when the counter reaches 0.
- 0x5555: enables write-accesses to the registers.
- 0xCCCC: enables the watchdog (except if the hardware watchdog option is selected) and write-protects registers.
- values different from 0x5555: write-protects registers.
Note that only IWDG_PR, IWDG_RLR, IWDG_EWCR and IWDG_WINR registers have a write-protection mechanism.
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