It's my first project in electrical engineering and I am not very sure about what I'm doing.
I would like to drive a relay thanks to a Rpi and a RTC clock that has a alarm feature (ds3231 with high-z/active low) ... relay that will itself drive the raspberry pi. To sum up:
- The RTC send a signal that turn on the Relay and thus the RPI
- The RPi reset the RTC alarm to it previous state and configure it to
trigger again in a determined time
- The Rpi do what it has to do
- The Rpi shut down and everything is back to normal I have to keep in mind to keep the current consumption as low as possible during the "sleep" phases
So far: I intended to use NPN transistor like on my scheme. in
- Both the Rpi and Ds3231 are High-z so the 5 V pull up and there is 5 V both in the base and emitter of the NPN => It doesn't let the current go. 2)The DS2132 become on open drain .. the NPN lets the current go
- the Rpi turn on and also become on open drain
My main preoccupation is: would this circuit work (and if not why?). I have of course to add a diode on the relay
Ps: A GPIO pin is in an high impedance state when no current is applied to Rpi, isn't it?