Hari Wiguna has shared on Hackaday.io his interesting scheme of making a 16-channel Wifi remote using the ESP8266 and PCF8574 I/O expander chips. PCF8574 device provides an 8-bit I/O expansion for any microcontroller through an I2C interface. This Wifi remote consists of a transmitting remote unit and a receiving control unit, both of which use an ESP-01 module and two PCF8574 devices. The remote unit has 16 push switches connected to the PCF8574 I/O pins, whereas the receiving unit has 16 LEDs connected in a similar fashion to the two PCF8574 chips. The remote ESP-01 module operates as a web client that reads the states of the push switches and send that info to the control ESP-01 module, which operates as a web server, as part of the web request. When a button is pressed on the client side, the web server responds to this request by changing the logic state of the corresponding LED on its end.