![Geehy SEMICONDUCTOR APM32F405 Series User Manual Download Page 266](http://html1.mh-extra.com/html/geehy-semiconductor/apm32f405-series/apm32f405-series_user-manual_573630266.webp)
www.geehy.com Page 265
Watchdog timer (WDT)
Introduction
The watchdog is used to monitor system failures caused by software errors.
There are two watchdog devices on the chip: independent watchdog and
window watchdog, which improve the security, and make the time more
accurate and the use more flexible.
The independent watchdog will reset only when the counter is reduced to 0, and
the value of refresh counter will not be reset until it is not reduced to 0.
The window watchdog will reset when the counter decreases to 0x3F. When the
count value of the counter is before the window value of the configuration
register, the refresh counter will also be reset.
Independent watchdog timer (IWDT)
Introduction
The independent watchdog consists of an 8-bit prescaler IWDT_PSC, 12-bit
count-down counter, 12-bit reload register IWDT_CNTRLD, key register
IWDT_KEY and state register IWDT_STS.
The independent watchdog has an independent clock source, and even if the
master clock fails, it is still valid.
The independent watchdog is applicable to the situations where an independent
environment is required but the accuracy requirement is not high.
Structure block diagram
Figure 65 Independent Watchdog Structure Block Diagram
Down counter
Prescaler
Reload value
Prescaler register
IWDT_PSC
Reload register
State register
Key register
LSICLK
IWDT reset