Question

3. A watchdog timer that uses timer with prescaler is connected to a12 MHz oscillator timeout should occur if the function watchdog reset is not called within 5 minutes. value should be loaded into the up-counter pair when the function is called. What Time with prescaler 16-bit서overflow. Clk Prescaler 16-bit up tosystem reset or z→ 16 - counter interrupt Mode

Answer 1

Given A time out is occurred if the function watch dog reset is not called within 2 minutes so watchdog timer is sat with a number N which producer a X minute delay rightarrow So when the function watch dog reset is called that loads the timer with N and comes back to original program The times counts up from N and when count becomes all zero's the timeout is occurred So N = (FFFF FFFF - N_TCLK) + 1 where T_CLK = number of clock cycles required to produce 2 minutes delay Given t_CLK = 12 MHz T_CLK = 1/12 times 10^6 = 1/12 mu S So N_TCLK = 2 minutes/1/12 Micro second = Number of clock cycles required to produce 2 minute delay = 2 times 60 sec/1/12 times 10^-6 sec = 2 times 10^-6 sec = 2 times 60 times 12 times 10^6 = 1440 times 10^6 and N = (2^32 - 1)(1440 times 10^6) + 1 in decimal form