SLAU847E October 2022 – May 2025 MSPM0L1105 , MSPM0L1106 , MSPM0L1116 , MSPM0L1117 , MSPM0L1227 , MSPM0L1227-Q1 , MSPM0L1228 , MSPM0L1228-Q1 , MSPM0L1303 , MSPM0L1304 , MSPM0L1304-Q1 , MSPM0L1305 , MSPM0L1305-Q1 , MSPM0L1306 , MSPM0L1306-Q1 , MSPM0L1343 , MSPM0L1344 , MSPM0L1345 , MSPM0L1346 , MSPM0L2227 , MSPM0L2227-Q1 , MSPM0L2228 , MSPM0L2228-Q1
The independent watchdog timer (IWDT) in the low-frequency subsystem (LFSS) is a device-independent supervisor which monitors code execution and overall hang up scenarios of the device. Due to the nature of LFSS, this IWDT has its own system independent power and clock source. If the application software does not successfully reset the watchdog within the programmed time, the watchdog generates a POR reset to the device.
Key features of the IWDT include:
Figure 28-1 shows the block diagram of the IWDT.
The typical use case of the IWDT is the replacement of an external watchdog timer in the system. Some safety applications require the monitoring of a device by an independent watchdog timer. This means the IWDT requires a system independent clock source and/or power supply. Both of these requirements are given with LFSS, which LFOSC control is independently contained inside LFSS and can optionally be independently powered by the VBAT supply pin (if the device includes VBAT).
The primary function of the IWDT is to initiate a full power on reset (POR) of the device when correct operation of the device has failed due to an unexpected software or system delay. The IWDT can be programmed with a predefined time within the application software.
The application software must restart the timer, indicating that application execution is proceeding normally. If application software fails to restart the timer within the specified time, the IWDT will issue a POR reset request to PMU of the device to generate a POR, restarting the device in a cold boot process.