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There is a problem in our application by using XC167-32F40. In the application,we use MC7805 as Peripheral Units PowerSupply,and LM1117 as CPU's PowerSupply.We take a EMC test for PowerSupply(7637-2b),and while the test is finish,the CPU is not working until give the /RESET a reset signal. By the way ,in our software,we use WDT module,but still no effect on this state. I hope for your help dealing with the problem .Thank you.
Have you verified that the watchdog is enabled and working during normal use? Just create a dummy loop and wait for a watchdog reset. If the external reset line can restart the processor, then it isn't in any latchup state so a watchdog should also be able to restart it.
Thank you for the uppers answer! Yes,I make a simple test for WatchDog.it would be reset while watchdog timer overflow in nomal running. However,there are some different between Not using watchdog module and using Watchdog module .In the first case,CPU went into latchup state in every pulse test. In the second case,CPU went into latchup state in specifical pulse test. I try to change watchdog serviced time,50ms to 822ms,but the problem still exist.
How are you driving the reset signal? An external supervisor or just a cap?
just a simple RC circuit by using a external key-press but not using any supervisor chip.