| 摘要 |
PROBLEM TO BE SOLVED: To adjust automatically a termination condition of a bus line in a transmission circuit. SOLUTION: Upon the receipt of data, voltages Va, Vb each having a waveform are given o a voltage waveform acquisition section 13. The voltage waveform acquisition section 13 samples a leading of the voltage Va in positive polarity and decrements a count of a pull-up resistor 14 by one through the discrimination of the presence of an unsharpened waveform when the Va is lower than a preset permissible value. When the Va is higher than the permissible value and a voltage Vab is smaller than a voltage Vd, since this means that an output of a differential input line receiver 12 is not certain, the section 13 increments the count of the pull-up resistor 14 by one. When the Va is higher than the permissible value and the voltage Vab is higher than the Vd, it is discriminated that no unsharpened waveform is in existence, the output is certain and the communication line is excellent, then the processing is terminated. A display device 17 indicates excellent of the communication line. |
