Patent ID: 6944246

Claim:
A data processing device, comprising a plurality of connection terminals for being individually supplied with signals, including processing data and a clock signal, and drive electric power; at least one radio antenna for receiving the signals and drive electric power as one radio wave; a data processing circuit switchable between a terminal mode, in which only the signals supplied to said connection terminals are effective, and an RF mode, in which only the radio wave supplied to said radio antenna is effective, said data processing circuit being supplied with the drive electric power and the signals; and a mode selecting circuit for setting said data processing circuit to the RF mode by default in response to the drive electric power starting to be supplied, and for switching said data processing circuit to the terminal mode in response to the clock signal being applied to a corresponding one of said connection terminals, wherein said mode selecting circuit comprises: clock counting means for counting clock pulses of the lock signal supplied in response to the drive electric power starting to be supplied; and input deciding means for outputting a switching signal to switch said data processing circuit to said terminal mode when said clock counting means has counted a predetermined number of clock pulses.