| 摘要 |
PURPOSE:To form a conversion value with high accuracy for a rear stage, by replacing the error of a digital value due to the discontinuous change of an analog signal at the maximum value or the minimum value that is the boundary value of the input range of an A/D converter by the boundary value. CONSTITUTION:A counter CNT is incremented under the constant condition of a comparator output S1, and a digital output S2 can be obtained. A digital value D from the A/D converter and the counter output S2 are read by a CPU simultaneously via a bus line B. The CPU reads the count value of the above counter at the time of starting and completing A/D conversion, and when the count value at the time of starting the conversion is different from that at the time of completing, the CPU judges that the A/D conversion of the analog signal changing discontinuously is performed. And as an A/D conversion value, the maximum value or the minimum value (that is, boundary value) of an A/D input range is adopted.
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