StopMode_Measure() function

This function configures the system to enter Stop mode with RTC clocked by LSI for current consumption measurement purpose. STOP Mode with RTC clocked by LSI ===================================== - RTC Clocked by LSI - Regulator in LP mode - HSI, HSE OFF and LSI OFF if not used as RTC Clock source - No IWDG - FLASH in deep power down mode - Automatic Wakeup using RTC clocked by LSI (~20s)