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Method and circuit for correcting frequency of universal serial bus (USB) device

A frequency and circuit technology, which is applied in the field of correcting the frequency of USB devices, can solve the problems of complex circuits, long time-consuming, inconvenience, etc., and achieve the effect of simplifying the correction circuit and reducing the correction time

Active Publication Date: 2011-05-18
ELAN MICROELECTRONICS CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this two-step calibration method of coarse tuning and then fine tuning is to use the first data frame in the data serial of the USB host side to perform rough tuning, and then use the second and third data frames in the data serial of the USB host side. It takes a long time to correct (three data frames), and the circuit required is also more complicated.
[0006] Therefore, there are above-mentioned inconveniences and problems in the known methods and circuits for calibrating the frequency of USB devices.

Method used

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  • Method and circuit for correcting frequency of universal serial bus (USB) device
  • Method and circuit for correcting frequency of universal serial bus (USB) device
  • Method and circuit for correcting frequency of universal serial bus (USB) device

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Embodiment Construction

[0075] The present invention will be further described below in conjunction with embodiment and accompanying drawing.

[0076] see now image 3 and Figure 4 , image 3 It is a schematic diagram of the first embodiment of the method for calibrating the frequency of a USB device according to the present invention, Figure 4 It is a schematic diagram of a first embodiment of a circuit for calibrating the frequency of a USB device according to the present invention. refer to Figure 1 to Figure 4 , as shown in the figure, in the step 22, the end of packet (end of packet; EOP) is between the end of a packet and the beginning of the next packet, and the detection unit 42 detects that the EOP in the USB host end data serial produces A reset signal R is given to the counters 46 and 48 to initialize the counters 46 and 48 to reset the counters 46 and 48 to zero. In step 24, the detection unit 44 detects an incoming packet in the USB host data stream. In step 26, the detection un...

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Abstract

The invention discloses a method for correcting the frequency of a universal serial bus (USB) device. The method is characterized by comprising the following steps of: (a) detecting a packet end input into a data stream so as to initialize a counter; (b) detecting an input packet in the data stream so as to identify whether the input packet is a token packet or not, performing a step (c) if the input packet is the token packet, or returning to the step (a) if the input packet is not the token packet; (c) identifying whether the input packet is a start of frame (SOF) token packet or not, triggering the counter to start counting the quantity of clock pulses if the input packet is the SOF token packet, or returning to the step (a) if the input packet is not the SOF token packet; (d) detecting the next SOF token packet in the data stream so as to latch the counter to generate a count value; and (e) comparing the count value with a reference value so as to adjust the frequency of an internally-adjustable oscillator and make the count value equal to the reference value.

Description

technical field [0001] The invention relates to a USB device, in particular to a method and circuit for correcting the frequency of the USB device. Background technique [0002] In the universal serial bus 2.0 and 1.1 driver protocol (USB 2.0 and 1.1 driver protocol), the interface communication protocol of the universal serial bus (USB) host (host) to the USB device (device) is for low speed (low speed) , Full speed (full speed) and high speed (high speed) operating frequency have strict specifications to correspond to different applications. For example, in the low speed state, the data rate specification (data rate specification) of the data serial (data stream) of the USB host is 1.5MHz±1.5%, which is applied to keyboards, mice, etc.; in the full speed state, the data stream of the USB host The serial data rate specification is 12MHz±0.25%, which is used in audio and microphones, etc.; in the high-speed state, the data serial data rate specification of the USB host is 4...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F13/42
Inventor 江宗殷王俊淇吴伯豪唐春安
Owner ELAN MICROELECTRONICS CORPORATION
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