I used to think STM8L would cost less energy than ATTINY. Today I got some time to view the datasheet for these two MCU.

First comes the STM8L datasheet:

If we just use low speed oscillator (LSI) in the STM8L, it would only cost 0.9uA when all other components has shutdown.

How about ATTINY? Then comes the datasheet:

Since we need to enable watch dog timer (WDT) to wakeup, the ATTINY cost typical 4uA in low power mode.

Seems my memory is still correct 🙂 STM8L is the winner.