Sonoff

http://recetastecnologicas.blogspot.com.es/2016/03/hackeando-el-itead-sonoff-un.html

http://tinkerman.cat/hacking-sonoff-rf-bridge-433/

http://www.instructables.com/id/Como-Conectar-El-SONOFF-WiFi-Switch-a-Ioadafruitco/

Cambiar Firmware

https://rutg3r.com/sonoff-firmware-tutorial-to-esp-easy/

Firmware alternativos

Tasmota