| 摘要 |
A key scan system by sensing a voltage level and a method thereof are provided to increase the efficiency of key scan by detecting an input voltage level in case that a key input signal is generated and performing a function of an input key according to the detected input voltage level, and extend the restricted number of pins by minimizing the use of I/O(Input/Output) pins and using the pins for other purposes. In case that the key input signal is generated, a CPU(100) detects the input voltage level inputted through a key input pin. The CPU performs the function corresponding to the input key by recognizing a high level if the detected input is higher than a predetermined reference level and recognizing a low level if not. The CPU recognizes/discriminates the high and low level of the input voltage level by using a single key input pin. The key input pin uses an A/D(Analog to Digital) pin for detecting the input voltage level.
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