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There are probably battery protection ICs ,but anyway, all ICs are built with transistors resistors etc..so in the end some simple functions can be achieved with few discrete parts .
T1 base ---^√^√^√^√^-------microcontroller pin 6.8kOf course you could also use the same pin of the mocrocontroller that sets the circuit off and set it to LOW to turn the circuit ON again. I will let you figure this part out :) (play with more transistors, watch out for shorts though)
You cannot shutdown the microcontroller if you want to wake it up automatically afterwards. What you can do is put all your sensors on the power output of this circuit (not the microcontroller) if they don't have a power saving mode. Then you should find out how to put your microcontroller to sleep (low power mode) and use a watchdog timer to wake it up. You should then connect the button pin that goes to the transistor to a microcontroller pin and set it high when you want to wake up the sensors.
Thanks. Yes, the circuit cuts all the flow from Input to Output, although it does not have to be the same power rail as the micro's. This kind of circuit might come handy when powering things from a lipo for example.
Auto Power Off: save batteriesView Instructable »