Circuit and method for real-time detection of master-slave machine with (USB) interface

Circuit and method for real-time detection of master-slave machine with (USB) interface

  • CN 102,680,818 B
  • Filed: 05/01/2012
  • Issued: 02/18/2015
  • Est. Priority Date: 05/01/2012
  • Status: Active Grant
First Claim
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1. a slave real-time detection circuit for USB interface, is characterized in that, comprising:

  • comparer, the first constant current source, the second constant current source, the first resistance and the second resistance;

    The positive pole of comparer is as test side, and it connects the D+ pin of detected slave USB interface;

    Drop-down first resistance of comparer positive pole, connects the first constant current source simultaneously, and design reaches comparer positive pole has individual logic low when accessing without the resistance beyond the first resistance;

    Drop-down second resistance of comparer negative pole, connect the second constant current source simultaneously, design reaches comparer negative pole has individual virtual voltage lower than the voltage of positive pole when accessing without the resistance beyond the first resistance when accessing without other resistance beyond the second resistance, design is when comparer positive pole accesses a D+ pull down resistor again, and the voltage of comparer positive pole is less than the voltage of comparer negative pole.

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