Can the M590E's boot pin be used to reduce power consumption?
It looks like to "BOOT" pin of the very common PCB for the module goes to the "ON/OFF" pin of the module itself. It looks like this pin can be held continuously low at power on and the module will power up and boot.  It appears to work like a switch that when you press it it pulls the pin low. The switch, if held for a while, toggles the power state of the module. There is also a power down command. I guess that I could use the power down command. (Its not clear if ON/OFF needs to be floating high to do this). I guess to wake it again I can let the BOOT pin float high for a while and then pull it low again, as though the switch was released and then pressed and held. I will try and remember to report back here if I get it working.