Semiconductor device and communication system

A semiconductor device, connectable via a first transmitting/receiving device capable of communication with an external transmitting device using a differential voltage method, and connectable via a second transmitting/receiving device capable of communication with an external first device using a differential voltage method, comprising:

• a first input terminal configured to be connectable to a first reception data output terminal of the first transmitting/receiving device;
• a first output terminal configured to be connectable to a first transmission data input terminal of the first transmitting/receiving device;
• a second output terminal configured to be connectable to a second transmission data input terminal of the second transmitting/receiving device;
• a second input terminal configured to be connectable to a second reception data output terminal of the second transmitting/receiving device;
• a first receiving section configured to be able to receive serial data as reception data from the transmitting device via the first input terminal;
• a first transmitting section connected to the second output terminal;
• a second receiving section connected to the second input terminal;
• and
• a second transmitting section connected to the first output terminal,
• wherein the first receiving section and the first transmitting section are configured to through-output data for the first device included in the reception data from the second output terminal when bridge selection data included in the reception data indicates an on state of a through-output in which bit data is output as is, and
• the second transmitting section keeps a signal level of the first output terminal so that a signal of a first bus, which the first transmitting/receiving device uses to receive the reception data from the transmitting device, becomes recessive when the through-output is being performed.