Mightyboost without Moteino

[robertoyok]

Can I use Mightyboost without the Moteino board to power-down a Raspberry Pi when the 5V wall plug is removed?   If so, can I replace the batteries with a 5.4VDC super cap?
Thanks,
Bob

[Felix]

No, MBoost is just a switch with a backup battery in case external power is lost so battery would pick up.
You will need the "brains" to sense when the power is lost and issue a shutdown to the Pi. The "brains" = Moteino.

[robertoyok]

Thanks, one follow up question.  If the mightyboost has a low voltage signal coming off the board can this be used to drive a GPIO on the Pi without Moteino?  Then the cpu on the pi monitors the GPIO and shuts down when the voltage is low.  I don't need a power switch or any other controls other than a clean shut down,  shutting down the pi when power is removed.

[Felix]

Technically you could yes. Just ensure you use a voltage divider if you're tapping into the 5V input. Use a high resistor value divider like 10K and 4.7K, into your GPIO pin.
I wonder though, how are you going to re-power it back on. The MBoost will continue to have its 5V output enabled, and there is no way to now tell when power comes back since the Pi is in a hibernation state.

[robertoyok]

Thanks for pointing out the flaw in my idea. Best regards