Host apparatus and extension device

A host apparatus configured to supply a power-supply voltage to a device and communicate with the device via signals of a clock, a command/response, and data, a first voltage signaling and a second voltage signaling lower than the first voltage signaling being usable for the communication as input/output signal levels of the signals, comprising:

• a power/ground terminal configured to supply the power-supply voltage to the device;
• a clock terminal configured to output the clock;
• a command terminal configured to transmit the command and receive the response;
• a plurality of data terminals including a 1st data terminal to a 4th data terminal, each being configured to perform input and output of the data;
• an I/O cell unit connected to the clock terminal, the command terminal, and the data terminals;
• and
• a device detection unit configured to detect whether the device is communicable under the second voltage signaling, wherein
• the host apparatus performs an initial setting where the host apparatus sets each of the clock terminal, the command terminal, the 1st data terminal, the 2nd data terminal, and the 4th data terminal to a Low level, and where the host apparatus sets the 3rd data terminal to the Low level or pulls down the 3rd data terminal via a resistor under the second voltage signaling,
• the host apparatus supplies the power-supply voltage via the power/ground terminal to the device,
• the device detection unit outputs one clock pulse to the clock terminal after passage of a first certain period of time from a start of supplying the power-supply voltage,
• the host apparatus determines the device as a LVS (Low Voltage Signaling) device when signal level of the 3rd data terminal has been inverted after passage of a second certain period of time from providing the one clock pulse.