| 摘要 |
PURPOSE:To make A/D conversion possible, by connecting only two signals lines from the microcomputer to the external circuit. CONSTITUTION:Operational amplifier Q3, capacitor C1, and resistance R5 constitute an integrating circuit. When A/D conversion starting signal AD becomes high-level and both ends of capacitor C1 are opened, the output of amplifier Q3 is increased from initial value 12V linearly with the inclination determined by time constant C1XR5. The output of amplifier Q3 is input to the noninversion input terminal of comparator Q4. Next, for the output of amplifier Q3 > analogue input, the output of comparator Q4 is inverted and is input to interrupt terminal INT of microcomputer MC1 through transistor Q5 to interrupt it. |
