Is it possible to keep the 5V on, while putting the Arduino (ATMEGA328P) in sleep more, using LowPower library?

I'm trying to use this HAT:


to control the power of my Raspberry Pi. But on top of it, I want to have a second HAT that I want to feed 5V input, event after I shut down Raspberry Pi and put the Arduino to sleep.

  • 1
    The 5V of an Arduino is always on. It's power, not a controllable pin. Or are you on about some functionality of this Pi hat that you link to (to a site which is completely meaningless TBH...)
    – Majenko
    Mar 5, 2020 at 13:12

1 Answer 1


If I read the schematics at https://spellfoundry.com/download/sleepy-pi-2-usb-c-schematic/ correctly, you need to draw continuous 5V power from the SUPPLY_5V pin instead of the SUPPLY_EXP_5V pin (the latter seems to be switched via some MOSFETs connected to pin 2 of the ATMEGA328p). Which means that you need to connect the 5V power of your second HAT to JP4 pin 3 on the Sleepy Pi HAT (instead of JP5 pin 3).

Not the answer you're looking for? Browse other questions tagged or ask your own question.