Finally I found a little time to continue my Home Automation System.
I already own a SONOFF 4 channel...I think the biggest one...
This device is able to drive 4 power outputs through a single Wifi connection. I will use it to power up my lights.
As well as input and output power connector,s it also has 4 pushbuttons which drive the 4 relays. Basically it's like 4 SONOFF Basic in a single device and with a single Wifi connection.
As usual I will use the TASMOTA firmware instead of the original one, which permits to use the device only through EWelink software. With TASMOTA firmware I'm able to easily integrate the device in OpenHAB using MQTT protocol.
Here is my SONOFF in flashing mode
As usual, it's easy to flash the firmware...just follow the official Wiki
Please, remember that this is an irreversible operation. You cannot recover the original firmware
In order to be able to control the SONOFF also through a traditional button, I decided to use the 4 pushbuttons integrated in the device... by connecting them appropriately to the buttons / wall switches ...
I never throw anything away and in this case a male / female old serial cable will be very useful to connect comfortably and plug and play the buttons / wall switches with the SONOFF buttons.
Thanks to Piero, we soldered the serial pins to the 4 pushbuttons on the SONOFF
getting the connector out of the SONOFF box
On the other side, we have an ethernet cable linked to the wall buttons
and we soldered to it the male serial connector
Ok, now it's time to configure the device to be integrated in OpenHAB through MQTT