Priority to the youngest...the just arrived SONOFF Basic
The first thing to do is testing it with no modification...in this way, if the device is bad, we could return it. The procedure is the standard one, explained here.
First, plug the device to the main power; the SONOFF Basic, differently from the SONOFF Pow, has INPUT and OUTPUT terminals splitted, one on each side and has no earth connection.
I connected the INPUT side to a standard plug and the OUTPUT side to a lampholder...
I connected the plug to a wall outlet and the SONOFF turned on. Now I have to download the EWeLink App on my android tablet. During the first setup, I created a new EWeLink account. Then I followed the pairing procedure (see https://www.itead.cc/wiki/EWeLink_Introduction). The app suggested me what to do in order to add the device; the following step was to store the wifi SSID and password to join my home network; the last step was to give a name to the device. Ok, now I can take control of the device through EWeLink app.
Ok, the device is working as expected with the default firmware. Now I may update it with the TASMOTA firmware, using the same procedure as the SONOFF Pow, described in and old post (http://domoticsduino.blogspot.com/2017/07/home-automation-system-first-sonoff.html); it's important to unplug the device from the main power when connected to serial interface.
The main difference is that the serial interface is located in the middle of the device, near the button, and it has 5 PIN (not 4 as the SONOFF Pow). The PIN located far from the button is GPIO0 and it is not part of the serial interface.
Here is the USB-Serial converter, connected to the SONOFF
And here is the WiFi configuration panel, as the result of the procedure already followed for the SONOFF Pow (https://github.com/arendst/Sonoff-Tasmota/wiki/Button-Usage).
As you can see, the TASMOTA firmware let us to manage two WiFi connections; so, if the first one is not reachable or its signal is very low, the device switches to the second one, and vice versa. Very good feature...
Now, finally I will try the MQTT protocol...