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Note: The watchdog function is in the V
DD
power supply area and can work normally in the shutdown or
standby mode.
Functional description
Key register
Write 0xCCCC in the key register to enable the independent watchdog, then the
counter starts to count down, and when the counter counts to 0x000, a reset will
be generated.
Write 0xAAAA in the key register, and the value of the reload register will be
reloaded to the counter to prevent the watchdog from resetting.
Write 0X5555 in the key register to rewrite the value of the prescaler register
and the reload register.
Regiser access protection
The prescaler register and reload register have the function of write protection.
If you want to rewrite these two registers, you need to write 0x5555 in the key
register. If you write other value in the key register, the protection of the register
will be started again.
Write 0xAAAA to the key register and the write protection function will also be
enabled.
Hardware watchdog
After the "hardware watchdog" function is enabled, and the system is powered
on and reset, the watchdog will run automatically. If 0xAAAA is not written to the
key register, reset will be generated after the counter finishes counting.
Debug mode
The independent watchdog can be configured in debug mode and choose to
stop or continue to work. Depend on DBGMCU_CFG register IWDT_STS bit.
Table 75 Min/max timeout when LSICLK=28kHz
PSC
Min timeout value
Max timeout value
0
0.125ms
512ms
1
0.25ms
1024ms
2
0.5ms
2048ms
3
1ms
4096ms
44
2ms
8192ms
5
4ms
16384ms
6
8ms
32768ms