Abstract: An apparatus for data input. The apparatus comprises 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 shift register circuit receiving a strobe signal, a 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 a microcontroller receiving the interruption signal, outputting the strobe signal and clock signal when the interruption signal is asserted, and serially receiving the group of data bits from the shift register circuit to identify the key being pressed.

Abstract: An apparatus for data input. The apparatus comprises 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 shift register circuit receiving a strobe signal, a 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 a microcontroller receiving the interruption signal, outputting the strobe signal and clock signal when the interruption signal is asserted, and serially receiving the group of data bits from the shift register circuit to identify the key being pressed.