Lesson2 - How to use Arduino to control relay ON/OFF

[admin]

because you have seen the lessons for input and relay output is for KC868-A4. KC868-A4 use ESP32 GPIO directly for input and output function.
But KC868-A8 use PCF8574 IIC chip to extend the GPIO for input and output use.
if you want to learn digital input and digital output by KC868-A8, see these links:
Lesson19- how to use PCF8574 IIC extend GPIO for ESP32 multi relay https://www.kincony.com/forum/showthread.php?tid=834
Lesson20- how to use PCF8574 IIC extend GPIO for ESP32 input ports https://www.kincony.com/forum/showthread.php?tid=838