An automatic serial signal detecting and transceiving device and related system and method are provided for detecting whether a connected initiator unit is using an inter-integrated circuit (I2C) interface protocol or a serial general purpose input/output (SGPIO) interface protocol. The device includes an input interface, connected to the initiator unit, and a control unit. A load pin of the input interface services either the SLoad signal line of an SGPIO bus, or the Reset signal line of an I2C bus. As the device is connected to different initiators, the control unit monitors the load pin for a trigger signal, thereby automatically detecting the interface protocol in use, and processes and transceives data in accordance with the detected interface protocol. The control unit also controls a light-emitting diode (LED) based on the detected interface protocol and data transmitted in accordance with the detected interface protocol.