Crystal-free USB device clock calibration method and calibration circuit

A device clock and calibration method technology, applied in the electrical field, can solve problems such as signal damage, misidentification, and loss of SOF packets, and achieve the effect of ensuring reliability and accurate detection results

Active Publication Date: 2019-04-26
珠海慧联科技有限公司
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  • Application Information

AI Technical Summary

Problems solved by technology

However, in the complex environment of circuit work, there are various interferences on the signal on the USB bus, and the signal on the USB will be destroyed at a transient moment, resulting in the probability of misidentification or loss of SOF

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  • Crystal-free USB device clock calibration method and calibration circuit
  • Crystal-free USB device clock calibration method and calibration circuit
  • Crystal-free USB device clock calibration method and calibration circuit

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Embodiment Construction

[0026] A crystal-less USB device clock calibration method and a calibration circuit provided by the technical solution of the present invention are suitable for crystal-less USB devices and chips with USB slave device interfaces. To clearly and completely describe the technical effect of the present invention, so as to fully understand the purpose, scheme and effect of the present invention.

[0027] It should be noted that, unless otherwise specified, when a feature is called "fixed" or "connected" to another feature, it can be directly fixed and connected to another feature, or indirectly fixed and connected to another feature. on a feature. In addition, descriptions such as up, down, left, and right used in the present disclosure are only relative to the mutual positional relationship of the components of the present disclosure in the drawings. As used in this disclosure, the singular forms "a", "the", and "the" are intended to include the plural forms as well, unless the ...

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Abstract

The invention relates to a crystal-free USB device clock calibration method and a calibration circuit, used for implementing the following steps: identifying and sampling an SOF packet on a USB bus, verifying the sampled SOF packet data, and outputting verification signals; counting the verification signals, comparing with a preset count value according to the counting result, and configuring a PLL parameter according to the comparison result; and clock-calibrating the RC oscillator of the USB internal clock and the PLL phase locked loop according to the PLL parameter. The invention has the beneficial effects that the information of the remainder part is retained, and the multi-phase sampling of the USB serial differential signal is carried out by using the fractional frequency dividing idea, so that the level characteristic of the USB serial differential signal can be accurately determined; all the information of the SOF packet is verified to ensure the reliability of SOF detection; the detection result will be more accurate; and in particular, the accuracy of the SOF packet detection of the invention is not affected by the internal clock bias to be calibrated.

Description

technical field [0001] The invention relates to a clock calibration method and a calibration circuit of a USB device without a crystal oscillator, belonging to the field of electricity. Background technique [0002] Due to its high versatility, strong scalability, simple interface, and convenient application, the USB interface has become one of the necessary standard interfaces for electronic equipment, and has been widely used in information communication and data transmission. The USB protocol has strict regulations on the rate of the interface signal. In the low-speed state, the data rate of the USB interface is 1.5MHz±1.5%, which is used in keyboards, mice, etc.; in the full-speed state, the data rate of the USB interface is 12MHz±0.25%, used in audio electronic equipment, etc., in the high-speed state Under the circumstances, the data rate of the USB interface is 480MHz±0.05%, which is applied to video-related electronic equipment. Therefore, in order to ensure the st...

Claims

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Application Information

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IPC IPC(8): H03L7/091H03L7/099H03L7/197
CPCH03L7/091H03L7/099H03L7/1974Y02D10/00
Inventor 徐明鹤
Owner 珠海慧联科技有限公司
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