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program segment is T, and the value of the window register is slightly less than
(TR-T), if there is no reload register in the window, it means that the program is
faulty, and when the counter counts to 0x3F, it will generate reset.
Figure 91 Window Watchdog Timing Diagram
Counter
Window
value
0x3F
Reload
counter
Generate
reset
Counter
Window
value
Reload counter
Generate reset
CNT＞window value
Start
Start
The calculation formula of window watchdog timer timeout is as follows:
T
WWDT
=T
PCLK1
×2
WTB
×
（
T[5:0]+1
）
Wherein:
T
WWDT
: WWDT timeout
T
PCLK1
: Clock cycle of APB in ms
Table 56 Minimum/Maximum timeout when PCLK1=36MHz
WTB
Minimum timeout value
Maximum timeout value
0
113μs
7.28ms
1
227μs
14.56ms
2
455μs
29.12ms
3
910μs
58.25ms
19.3.3.1
Debug Mode
The window watchdog can be configured in debug mode and choose to stop or
continue to work. It depends on the WWDT_STS bit of DBGMCU_APB1F
register in DBGMCU module.
19.4
IWDT Register Address Mapping
Table 57 IWDT Register Mapping
Register name
Description
Offset address
IWDT_KEY
Key register
0x00
