Universal serial bus device capable of adjusting central level automatically

Abstract

The invention discloses a universal serial bus device capable of adjusting central level automatically. An adaptive cutter is used to judge whether the central level of the USB device is consistent with the central level used by a USB element or not according to the features of an analogue signal used by the USB, and raises and lowers the central level of the USB device, which is used for converting the analogue signal into a digital signal according to the judgment result so as to make the bit stream transmitted by the USB element to the USB device be converted and judged correctly.

Description

technical field [0001] The invention relates to a universal serial bus device, in particular to a universal serial bus device with a level adjustment module. Background technique [0002] The standard Universal Serial Bus Apparatus (USB Apparatus) uses a master / slave (master / slave) architecture, the USB host (USB Host, also known as USB OTG) is the "master", and the USB peripheral device ( Peripheral, or USB component, USB Device) is "slave". Only the USB host can schedule connection settings and data transmission; USB peripheral devices cannot initiate data transmission, but can only respond to commands from the host. [0003] Generally, when a USB device is used to exchange data between a USB component and a USB host, the USB component and the USB host each have a central level to ensure that the bit 0 and bit 1 transmitted by the USB component in the form of a bit stream can be accurately read. judgment. Please note that the USB components cited here to explain this em...

AI Technical Summary

Problems solved by technology

[0006] exist image 3 Among them, the center level used by the USB host side is lower than the center level used by the USB component specification; when the USB component transmits data to the USB host side, the analog signals DP and DM use the center level to determine the bit value , and when the analog signal DP changes from a low level to a high level, a part of the signal that is recognized as a low level by the USB component will be converted into a bit 1 representing a high level by the USB host in the digital signal DDP, resulting in an analog The inconsistency between the signal DP and the digital signal DDP causes errors. In other words, some of the analog signal DP that should represent a low level is prematurely judged to be a bit 1 of a high level. image 3 The error shown

When the analog signal DM changes from a high level to a low level, there will also be a part of the signal that is recognized as a low level signal by the USB component in the digital signal DDM. Convert the digital signal DDM to bit 0), thus also causing the error caused by the inconsistency between the analog signal DM and the digital signal DDM

[0007] In the same way, in Figure 4 Among them, the center level used by the USB host side is higher than the center level used by the specifications of the USB components; when the analog signal DP and DM judge the bit value through the center level, the analog signal DP enters from the low level When the high level is high, some of the signals that are recognized as high by the USB component are converted by the USB host in the digital signal DDP to bit 0 representing low level (that is, converted to bit 1 too late), resulting in signal inconsistency. In the same way, the analog signal DM will also have a part of the signal that is recognized as a low level signal by the USB component. In the digital signal DDM, the USB host side converts it into a bit 1 representing a high level (that is, it is converted to a bit 0 too early. ), thus also causing signal inconsistency errors

[0008] From the descriptions of the above figures, it can be seen that when the center levels used by the USB component and the USB host end are inconsistent, the bit stream transmission between them will also easily change from high to low or from low to low in the analog signal level. When turning high, the judgment is too fast or too slow, which will lead to the error in the judgment of the converted digital signal

Furthermore, due to the wide variety of USB components currently on the market, the phenomenon of different standards is also very likely to occur in specifications, so the above-mentioned problems related to the center level of USB devices also occur more frequently.

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