2 FREQUENCY SIGNAL CONTROL CIRCUIT & METHOD FOR TELEPHONE

摘要

a filter(10) for receiving pulse-code-modulated data and filtering it into 2-frequency signal for telephone; an amplifier(20) for amplifying the filtered signal; a converter(30) for receiving the amplified signal, converting it into 4-bit hexadecimal code and latching data converted by a tone output enable signal; and a controller(40) for controlling the 4-bit hexadecimal code to be read by a CPU through a data line.