Please refer to the Code Example: CE210292 - PSoC 4S Watchdog Timer. The link to the code example is:
This code example demonstrates the basic capabilities of the WDT such as deep-sleep wakeup source and system reset counter. It configures the WDT to generate an interrupt every 500 ms and a reset on the third unserved interrupt (1.5 seconds). It turns on an LED to show the device reset caused by the WDT and toggles an LED to show the periodic interrupt generated by the WDT. The example also uses the ILO compensate APIs to improve the accuracy of the WDT interrupt generation.
Hope this helps. Let me know if you have further queries on this.