Unlock instant, AI-driven research and patent intelligence for your innovation.

Method for automatically regulating clock frequency and clock frequency regulating circuit

A clock frequency, automatic adjustment technology, applied in the direction of generating/distributing signals, etc., to achieve the effect of reducing costs

Active Publication Date: 2009-12-16
PIXART IMAGING INC
View PDF2 Cites 13 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method is only limited to low-speed USB interface connection systems

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Method for automatically regulating clock frequency and clock frequency regulating circuit
  • Method for automatically regulating clock frequency and clock frequency regulating circuit
  • Method for automatically regulating clock frequency and clock frequency regulating circuit

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0023] In order to make the above and other objects, features and advantages of the present invention more obvious, the following specifically lists the embodiments of the present invention, and together with the accompanying drawings, the detailed description is as follows.

[0024] Please refer to figure 1 As shown, it shows a timing diagram of differential signals when the USB device of the embodiment of the present invention is connected to the USB system, including the USB positive differential signal D+ and the USB negative differential signal D−. In the early stage of connection, such as time t in the figure 1 ~t 2 During the period, the USB device will receive a USB reset (reset) signal from the USB interface. Then, after each frame interval time (frame interval time), that is, 1 millisecond (ms), for example, t in the figure 2 ~t 3 , t 3 ~t 4 During ..., no matter whether data transmission is performed or not, the USB device will continue to receive the Keep Ali...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention relates to a method for automatically regulating clock frequency for a USB interface, comprising the following steps: generating a clock signal with adjustable frequency; receiving a USB differential signal; counting the clock signal according to a frame period of the USB differential signal to obtain the counting value; and regulating the frequency of the clock signal when the counting value exceeds a preset counting range. The invention also provides a clock frequency regulating circuit.

Description

technical field [0001] The invention relates to a method for automatically adjusting the clock frequency and a clock frequency adjusting circuit, in particular to a method for automatically adjusting the clock frequency of a clock generator in a USB device and the frequency adjusting circuit. Background technique [0002] A Universal Serial Bus (USB) system is composed of a USB host (host) and a USB device (device) connected through a USB interface (interface). The data transfer rate between the USB host and the USB device must meet the data transmission specifications, such as In a full speed device, the data transfer rate must be between 12MHz±0.25%; and in a low speed device, the data transfer rate must be between 1.5MHz±1.5%. One method currently used to control the clock frequency accuracy of the clock generator (oscillator) in the USB device to meet the above specification is to additionally set a crystal oscillator to increase the clock frequency accuracy. However, i...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): G06F1/08
Inventor 刘祥生
Owner PIXART IMAGING INC