SCAN METHOD FOR KEYBOARDS

摘要

A scan method for keyboards is firstly to set a higher voltage or a lower voltage to a keyboard scan input/output port when a low voltage signal is generated at a keyboard scan input port, and then to detect a voltage at the keyboard scan input/output port or the keyboard scan input port so as to determine whether the detected low voltage signal is a valid button-depressed signal or a noise. Further, a grounding resistor is connected electrically to the keyboard scan input/output port, and the scan method prevails as well to determine whether or not a detected low voltage signal is a valid button-depressed signal.

主权项

1. A scan method for keyboards, applied to a keyboard module, the keyboard module including a keyboard scan input contact, a keyboard scan input/output contact, a button and a firmware, the button being electrically connected with the keyboard scan input contact and the keyboard scan input/output contact, the firmware being electrically connected with the keyboard scan input contact and the keyboard scan input/output contact, the scan method comprising the steps of:
(a) setting a voltage at the keyboard scan input/output contact to be an output voltage while the firmware detects a low voltage signal being generated by the keyboard scan input contact; (b) detecting if a voltage at the keyboard scan input contact is a low voltage or not; setting the voltage at the keyboard scan input/output contact to be an input voltage while the voltage at the keyboard scan input contact is the low voltage; and (c) detecting if the voltage at the keyboard scan input/output contact is a high voltage or not; determining the low voltage signal to be a button signal and performing a signal masking process within an oscillation time duration of the low voltage signal while the voltage at the keyboard scan input/output contact is the high voltage.