| 摘要 |
The serial data interface disclosed has power signal and data signal contacts. The power signal contact has an associated impedance, which is automatically sensed for discrete changes in the impedance. The impedance may have different values when a peripheral device is connected and when not connected. The sensor may automatically sense the change from one value to the other. The impedance change may be related to a threshold value. The sensor may sense the capacitance of the power signal contacts, and the sensor may apply an alternating voltage signal to the power signal contacts. The AC may be less than 0.2V. The sensor may have an oscillator which supplies the AC voltage at a frequency dependent upon the capacitance of the power signal contact. The capacitance may be less than 2 microfarads. The sensor may sense the change in resistance of the power signal contacts, which may be 100 Kohms. The sensor may comprise a comparator and at least one voltage divider. The interface may be for a USB connection port. |
