These are the first feature including the MQTT in the hydrosys4, so far the hydrosys4 supports only the unencrypted mode (so please use only in local network), the plan is to add encryption mode in later releases.
First step is to load the tasmota SW in the ESP01s (ESP8266 chipset). The pre-compiled SW to choose is called tasmota-sensors.bin. (link)
In this test I connected the BH1750 light sensor to the device. According to the tasmota documentation, when the MQTT full topic should be composed as follow: tele/%topic%/SENSOR .
At first start the device will create its own wifi network (access point mode), we require to access to this network, open the webbrowser and type the following address: 192.168.4.1. The initial configuration will be displayed where it is possible to insert the Wifi network credentials.
After the wifi setting is terminated, the device should automatically attach to the wifi network. At this point we require to find the IP address of the device (normally by accessing to the router).