Patent ID: 7737736

Claim:
An interface circuit comprising: a transmission-side circuit: including a selecting circuit for switching between inputting a normal data signal and a repetitive signal from a signal generating circuit based on a switchover control signal; an output buffer circuit for receiving the repetitive signal from the selecting circuit and outputting an output signal, to be input into and transmitted through a transmission path; and an amplitude adjusting circuit for adjusting an amplitude of said output signal that is output from said output buffer circuit; and a reception-side circuit: including: a comparator for comparing an amplitude of the output signal input into and transmitted through said transmission path with a predetermined reference value; and a determining circuit for determining a relation of magnitude between the amplitude of the output signal input into and transmitted through said transmission path and the reference value based upon said comparison result, and outputting a determination result of said determining circuit so that the result is conveyed to said amplitude adjusting circuit.