Sleep Modes:

The SX126X series LoRa radios define two different sleep modes, namely:

i) Sleep mode with Cold Start (default mode in Mbed LoRaWAN stack)
ii) Sleep mode with Warm Start


Sleep mode with Warm Start:
This is the default sleep mode for this driver. Radio configurations are retained in this mode. 
Typical power consumption in this mode is '600 nA'.


Sleep mode with Cold Start:
The driver can be configured to sleep with cold startup. This mode is the lowest power consuming state 
for the SX126X series radios. No configurations are retained in this mode, that's why our driver takes 
extra measures to keep backups of the configuration in the RAM. Typical power consumption in this mode
is '160 nA'. The radio takes about 3.5 milliseconds to wakeup properly because upon going to sleep all
components gets turned off. The radio thread blocks for that period of time. However, to reduce the impact 
of this wakeup time on the time critical operations, the stack shouldn't put the radio to standby rather than 
sleep before performing time critical operations. Mbed OS LoRaWAN stack handles this automatically which means
that the user can safely use sleep mode with cold start.