Low-power Stop2 mode

[Praneethsvch]

New sleep feature - Stop 2

Stop 2 mode has been implemented. Wake-up when the TxTimer in LoRaWAN/lora_app.c is triggered. Before and after Sleep Hook following are implemented:

• LPUART1 deInit and Init - used by MaxBotix
• UART2 debugging has been disabled to achieve lowest power - Serial port debug output (if needed enable debugging in Inc/sys_conf.h)
• GPIOs are configured Analog before every sleep and only necessary ones are initialized upon wake-up to save power
• ADC works - verified reading using OTII - 0.1 V inaccuracy see issue ADC inaccuracy - new prototype #41

Following is the power consumption analysis before (green) after (purple). Seeing beautiful micros!

Sleep consumption numbers:

Avg few minutes (1 min duty cycle):

Todo

• ADC deinit and Init. Calibration upon RESET only and save values to FLASH as state isn't preserved
• LED is disabled currently when powered on in STOP2 -> enable until join only. To enable Write LED_Pin High and enable clock for LED_Port. Redo the same after wake-up as the state is not preserved
• Solar charger IC on while STOP 2 sleep -> Similar to LED write high and enable CLK before sleep