Deep sleep mode for the Uno without complicated circuits?
Deep sleep mode for the Uno without complicated circuits?


Forget using an Arduino Uno if you want to do low power (less than 10 mA standby). There is too much extra circuits (LEDs, Voltage Regulators, etc) to allow that. 

See for instance, https://www.gammon.com.au/forum/?id=11497

With an Arduino Pro Mini it is possible to achieve low power after removing the Power LED and cutting the Voltage Regulator.

The hardware/software support for low power cannot really be used before the board is design for that. 

Cheers!