RTOS and stop mode

Kernel
9

Waking from deep sleep used to cost a lot more energy. I just ran some quick tests on a modern low-power CM4 (STM32L4, used by the OP).

   while (1)
   {
      vTaskDelay(2); // or 4 or 25, see below
   }

Average current, core clock at 16MHz (HSI):

Wake up every (ms):   2         4         25
  From Stop 2 (mA):  0.31      0.15      0.027
   From Sleep (mA):  1.52      1.43      1.36

Average current, core clock at 48MHz (MSI):

Wake up every (ms):   2         4         25
  From Stop 2 (mA):  0.31      0.15      0.027
   From Sleep (mA):  3.5       3.4       3.3

That’s some strong motivation to use stop mode aggressively in a low-power application.