tasmota FW and config file

[admin]

KC868-AI have 40 digital input ports. where you seen have 40 ports?
tasmota support MAX 32 channel GPIO, so you can use total 32 channels.
just download tasmota fimrware, enable PCF8574 function is ok.
you can use tasmota flash tool to download firmware, we have many tasmota video tour, you can check , use by same way.