ESP8266 reset causes | boot mode, list? - From http://www.esp8266.com/viewtopic.php?p=2096#p2112
reset causes:
0:
1: normal boot
2: reset pin
3: software reset
4: watchdog reset
boot device:
0:
1: ram
3: flash - See more at: http://www.esp8266.com/viewtopic.php?p=2096#p2112