Design of Keyboard Input Interface in Intelligent Instruments

A keyboard interface design using five buttons is introduced in this paper, which can realize functions such as keyboard-Unlocked, menu selection, data modification, menu item or data confirmation and so on. Independent type keyboard circuit was formed by using the five buttons, the number of interruptions was counted in the interrupt service subroutine, the interruptions were caused by timer overflow, some things can be achieved according to the number of counting and real-time button status, such as Jitter Eliminating, key assignments acquisition and identification of information about press or press and hold. Which guaranteed that the real-time response of keyboard input saved the software costs of system, the multiplexing function of a single key can be realized at the same time. On the design of key function subprogram, Flag Register was used, such as keyboard-unlocked, Permission to modify the menu, Permission to modify the data, which has improved the fault-tolerant of the keyboard operation. The keyboard was used in the development of some instruments, and has been proved stable and reliable in practice.