I am trying to build low power (coin cell CR2032 powered) simple device that would be used to transmit occasional messages (pushbutton or beacon) by using RFM69 module.
For this I have selected to use ATmega328p MCU mainly because I have (some) experience with it.
I did manage to have a working setup, however only when I power the device externally. It is not working when powered with CR2032 (because it draws too much current). I am still trying to figure out why, I will start debugging tonight, however I would appreciate if someone with more experience could take a look at my schematic and comment if there are obvious design flaws.
I am measuring current consumption of around 40mA

, although I am putting ATmega and RFM69 to low power modes (using LowPower library for ATMega and radio.sleep for RFM69).