| 摘要 |
PURPOSE: A system for automatically detecting the polarity of a signal is provided to minimize the performance deterioration effect of the system by using the interrupt only when the polarity of the input signal is changed. CONSTITUTION: A system for automatically detecting the polarity of a signal includes an up-down counter(100), a first sensor(200), a second sensor(300) and a polarity determination unit(400). The up-down counter(100) selectively performs the up-count approaching to the upper target value and the down count approaching to the low target value in response to the level of the input pulse signal to output the result as a plurality of bits. The first sensor(200) senses whether the up-down counter(100) reaches to the lower target value or not. The second sensor(300) senses whether the up-down counter(100) reaches to the upper target value or not. And, the polarity determination unit(400) outputs the signal to determine the polarity of the input signal pulse in response to the status of the upper target value or the lower target value.
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