Frequency correcting device and its method USB interface built-in vibrator

Abstract

The method is applicable to data transmission interface of USB. First, the method senses and calculates error values of bit-rate at USB host end and USB component end automatically to cooperate with Delay Lock Loop (DLL) to generate fine counting time to measure error value of clock pulse. Then, through quantization, digitization and calculation for error value of clock pulse, the method adjusts oscillation frequency of oscillator based on calculated quantized codes so as to correct error value of clock pulse between oscillation frequency at USB component end and frequency at USB host end in order to ensure correctness when system data are transferred. The invention also discloses frequency correction device for built in type oscillator of USB interface.

Description

technical field [0001] The invention relates to frequency correction of an oscillator, in particular to a frequency correction device and method for a built-in oscillator of a USB interface. Background technique [0002] On traditional devices, such as Phase Lock Loop (Phase Lock Loop, referred to as PLL) architecture, it is impossible to determine the bit rate (bit-rate) of the data stream (datastream) in the USB (Universal Serial Bus, Universal Serial Bus) data transmission specification. ) for latch synchronization. Because the phase-locked loop requires a long and continuous input reference clock (input reference clock) to achieve lock, it requires a lengthy lock time (Lock time), and the designed circuit must be accurate, otherwise it will easily cause clock errors , so as to cause the possibility of mistaking the reference signal. [0003] However, US Patent No. US6,407,641 "AUTO-LOCKING OSCILITOR FOR DATA COMMUNICATION" discloses a technology to improve the above pr...

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Problems solved by technology

[0004] Although the technology disclosed in U.S. Patent No. 6,407,641 has improved the existing problems, it still needs four bits of input reference data in the processing program of the coarse adjustment circuit 106, and also needs four bits of input reference data in the processing program of the fine adjustment circuit 108. Twenty bits of input reference data, so the patented technology still needs to count the lengthy host USB packet data as a reference signal

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