Patent ID: 7915919

Claim:
A digital interface sensing apparatus comprising: a sensor to sense an external analog signal; an analog detecting circuit to detect the sensed analog signal from the sensor; an analog to digital (A/D) converter to convert the sensed analog signal to a digital signal, and receive a clock signal and a data demand signal, wherein the A/D converter sends the digital signal in response to the A/D converter receiving the clock signal and the data demand signal; a signal cable comprising first to third lines; and an interface adjusting circuit comprising first and second voltage sources, a Zener diode, and first and second electronic switches, the first voltage source is connected to a first terminal of the first electronic switch, a second terminal of the first electronic switch is grounded, a control terminal of the first electronic switch is connected to a data pin of the A/D converter, the data pin of the A/D converter is also connected to the cathode of the Zener diode, the anode of the Zener diode is grounded, a clock pin of the A/D converter is connected to a first terminal of the second electronic switch, the second voltage source is connected to the first terminal of the second electronic switch, a second terminal of the second electronic switch is grounded, a control terminal of the second electronic switch is connected to the first line of the signal cable, the first terminal of the first electronic switch is connected to the second line of the signal cable, the control terminal of the first electronic switch is connected to the third line of the signal cable, the first voltage source satisfies the voltage standard of recommended standard 232 interface, the second voltage source and a stable voltage of the Zener diode both satisfy the voltage standard of inter-integrated circuit interface.