A semiconductor system may include a first semiconductor device and a second semiconductor device. The first semiconductor device may output command/address signals and receives temperature codes. The second semiconductor device may sense an internal temperature if a combination of the command/address signals is a first combination, generate and output the temperature codes having a combination corresponding to the internal temperature if a combination of the command/address signals is a second combination, and adjust a period of the temperature codes in accordance with a temperature section of the internal temperature.