I got a trouble when I powered ON a circuit with 555 which is used in monostable mode. The schematic is as follows.
Fig. 1 Watchdog timer circuit with 555 Expected behaviour Trig in is connected to a digital output pin of a microprocessor. The microprocessor sets Trig in to Low every several hundreds of milliseconds for few milliseconds. Watchdog out is supposed to be Low only when the microprocessor fails to set the Trig in to Low within 1.
