OKY3421 is a type of integrated circuit manufactured by OKYSTAR. It is a universal multi-channel temperature/humidity controller with a microprocessor as its core. It has built-in temperature/humidity adjusters and various communication interfaces, including RS232/RS485, USB, and relays. It can be used for various applications such as smart home heating and ventilation control, air conditioner adjustment, industrial humidification, and precision temperature control. It also supports programming, remote control, and alarm.