Apparatus for data input and key detection method thereof

An apparatus for data input comprising:

• a sensing circuit for a plurality of keys, outputting an interruption signal and a corresponding group of data bits when one of the keys is pressed;
• a control circuit coupled to the sensing circuit outputting a strobe signal and clock signal when the interruption signal is asserted;
• a shift register circuit coupled to the sensing circuit and control circuit, receiving the strobe signal, the clock signal and the group of data bits in parallel from the sensing circuit when the strobe signal is asserted, and serially outputting the group of data bits in synchronization with the clock signal;
• and
• an identifying circuit coupled to the shift register circuit and serially receiving the group of data bits from the shift register circuit to identify the key being pressed.