Provided are a device connected to another device by a single wire and a method of operating a system including the devices. The method of operating the device connected to the other device by the single wire includes transmitting a first packet to the other device, waiting to receive a second packet from the other device, and receiving the second packet from the other device. When the waiting to receive the second packet is started, electrically connecting a first end of a resistor to the first wire, and when the waiting to receive the second packet is terminated, electrically disconnecting a resistor from the first wire. A second end of the resistor is connected to either a logic high level voltage source or a logic low level voltage source.