What is the use or application of SV Call and NMI Exception in ARM Cortex M0 .
Is it someway related to RTOS?, if so , how?
Well that's the general idea of a watchdog timer. If the system isn't handling interrupts properly in a timely fashion then perhaps the best thing to do is just reset and then tell whatever or whoever should be talking to it that it had a problem. There's lots of things like that one might want to check - an error whilst recovering from an error, too many errors in a short time, otherwise unhandled errors, any sort of software check showing the work isn't completing, anything like that. Sometimes it is better to go to a degraded service mode but I'm of the all or nothing camp normally.