阅读说明：本技术 Tdm接口扩展方法及装置、设备、可读存储介质 (TDM interface extension method, device, equipment and readable storage medium ) 是由 孟庆晓 吴闽华 郭军勇 于 2019-08-07 设计创作，主要内容包括：本申请涉及TDM接口扩展方法及装置、设备、可读存储介质,所述方法包括：将处理器外接一FPGA芯片；控制通过FPGA芯片为处理器提供TDM接口时钟信号和同步信号,并通过FPGA芯片实现时隙的交换功能；控制处理器初始配置为从模式来接收FPGA的时钟信号和同步信号；控制处理器将数据写入到发送缓冲区,并通过TDM接口依次发送到对端；对端的数据通过TDM接口依次存入到接收缓冲区；通过FPGA芯片将处理器的TDM接口的时钟信号和帧同步信号的频率提高到原来的N倍；并且功能不受限,支持的时隙多,传输速率高。(The application relates to a TDM interface extension method, a device, equipment and a readable storage medium, wherein the method comprises the following steps: externally connecting the processor with an FPGA chip; controlling to provide a TDM interface clock signal and a synchronous signal for the processor through the FPGA chip, and realizing the exchange function of time slots through the FPGA chip; the control processor is initially configured to receive a clock signal and a synchronization signal of the FPGA from the mode; the control processor writes the data into a sending buffer area and sequentially sends the data to an opposite terminal through a TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; increasing the frequency of a clock signal and a frame synchronization signal of a TDM interface of the processor to be N times of the original frequency through the FPGA chip; and the function is not limited, the supported time slots are more, and the transmission rate is high.)

1. A TDM interface extension method, the method comprising:

externally connecting the processor with an FPGA chip;

controlling to provide a TDM interface clock signal and a synchronous signal for the processor through the FPGA chip, and realizing the exchange function of time slots through the FPGA chip;

the control processor is initially configured to receive a clock signal and a synchronization signal of the FPGA from the mode;

the control processor writes the data into a sending buffer area and sequentially sends the data to an opposite terminal through a TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; the frequency of a clock signal and a frame synchronization signal of a TDM interface of the processor is increased to be N times of the original frequency through the FPGA chip.

2. The TDM interface expansion method according to claim 1, wherein the step of externally connecting the processor to an FPGA chip further comprises:

the control processor applies for 2 DMA channels, one DMA channel transfers the data of the processor memory to the sending buffer area, and the other DMA channel transfers the data of the receiving buffer area to the processor memory.

3. The TDM interface expansion method according to claim 1, wherein the step of externally connecting the processor to an FPGA chip comprises:

connecting a BCLK pin of a processor with a BCLK pin of an FPGA chip;

connecting an LRCK pin of a processor with an LRCK pin of an FPGA chip;

connecting an SDI pin of the processor with an SDO pin of the FPGA chip;

and connecting an SDO pin of the processor with an SDI pin of the FPGA chip.

4. The TDM interface expansion method according to claim 1, wherein the control processor writes data into a transmission buffer and sequentially transmits the data to the opposite terminal through the TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; the method for increasing the frequency of the clock signal and the frame synchronization signal of the TDM interface of the processor to be N times of the original frequency through the FPGA chip comprises the following steps:

one frame originally supported by the processor is made into subframes, and N subframes are transmitted in a sampling period of voice, wherein the sampling period of the voice is 8000HZ, namely, the sampling period of one voice is 125 us.

5. The TDM interface expansion method according to claim 1, wherein the control processor writes data into a transmission buffer and sequentially transmits the data to the opposite terminal through the TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; increasing the frequency of the clock signal and the frame synchronization signal of the TDM interface of the processor to the original N times through the FPGA chip further comprises:

n LRCK signals will be generated uniformly in time 1/8000 ═ 125us, while BCLK in N FS also becomes 256 × N; such a frame transfers 32 x N bytes of data.

6. The TDM interface expansion method according to claim 1, wherein the increasing the frequency of the clock signal and the frame synchronization signal of the TDM interface of the processor to N times the original frequency by the FPGA chip comprises:

providing a transmission capability of data by doubling the frequency of the TDM clock signal and the frame synchronization signal; adopting a signal format with N sub-frames in a large frame; the frequency of the clock signal and the frame synchronization signal of the TDM interface of the processor is increased to N times of the original frequency.

7. A TDM interface extension apparatus, the apparatus comprising:

the system comprises a processor and an FPGA chip connected with the processor;

the first control module is used for controlling the TDM interface clock signal and the synchronous signal provided for the processor through the FPGA chip and realizing the time slot exchange function through the FPGA chip;

a second control module for controlling the processor to be initially configured to receive the clock signal and the synchronization signal of the FPGA from the mode;

the third control module is used for controlling the processor to write the data into the sending buffer area and sequentially sending the data to the opposite terminal through the TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; increasing the frequency of a clock signal and a frame synchronization signal of a TDM interface of the processor to be N times of the original frequency through the FPGA chip;

and the fourth control module is used for controlling the processor to apply for 2 DMA channels, wherein one DMA channel transmits the data of the memory of the processor to the sending buffer area, and the other DMA channel transmits the data of the receiving buffer area to the memory of the processor.

8. The TDM interface expansion device of claim 7, wherein the BCLK pin of the processor is connected to a BCLK pin of the FPGA chip;

an LRCK pin of the processor is connected with an LRCK pin of the FPGA chip;

an SDI pin of the processor is connected with an SDO pin of the FPGA chip;

and an SDO pin of the processor is connected with an SDI pin of the FPGA chip.

9. An apparatus comprising a memory and a processor, the memory storing a computer program, wherein the processor is external to an FPGA chip, and wherein the processor implements the steps of the method of any one of claims 1 to 6 when executing the computer program.

10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 6.

Technical Field

The present application relates to the field of processor technologies, and in particular, to a TDM interface extension method, apparatus, device, and readable storage medium.

Background

Existing VoIP (voice over IP) systems typically employ a CPU to process call control messages and a dedicated voice DSP (digital signal processor) to process voice codecs that provide a TDM (time division multiplexing mode) interface to access the data for the time slot exchange. With the improvement of the processing capacity of the CPU, an ARM processor with a 1.8Ghz 4 core can process hundreds of voice coding and decoding algorithms, and the processing capacity can meet the application occasions of most VoIP systems.

In order to reduce the cost of the device, a processing program of a coding and decoding algorithm can be run on the ARM processor to replace a professional DSP chip. There are many ARM chips with such operation capability on the market, but there are few ARM processor chips capable of supporting the TDM interface, and the function of the TDM interface of the ARM chip capable of supporting the TDM interface is not perfect, and the supported time slot is few, and the transmission rate of the whole TDM interface is low.

Therefore, the prior art is in need of improvement.

Disclosure of Invention

The invention provides a TDM interface extension method, a device, equipment and a readable storage medium, and aims to solve the technical problem that the TDM interface extension method can support the rate of 32 × N time slots, 2 × N M. (N ═ 1,2,4,8, 16); and the function is not limited, the supported time slots are more, and the transmission rate is high.

The technical scheme of the invention is as follows:

a TDM interface extension method, wherein the method comprises:

externally connecting the processor with an FPGA chip;

controlling to provide a TDM interface clock signal and a synchronous signal for the processor through the FPGA chip, and realizing the exchange function of time slots through the FPGA chip;

the control processor is initially configured to receive a clock signal and a synchronization signal of the FPGA from the mode;

the control processor writes the data into a sending buffer area and sequentially sends the data to an opposite terminal through a TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; the frequency of a clock signal and a frame synchronization signal of a TDM interface of the processor is increased to be N times of the original frequency through the FPGA chip.

The TDM interface extension method, wherein the step of externally connecting the processor with an FPGA chip, further comprises:

the control processor applies for 2 DMA channels, one DMA channel transfers the data of the processor memory to the sending buffer area, and the other DMA channel transfers the data of the receiving buffer area to the processor memory.

The TDM interface extension method comprises the following steps of connecting a processor with an FPGA chip externally:

connecting a BCLK pin of a processor with a BCLK pin of an FPGA chip;

connecting an LRCK pin of a processor with an LRCK pin of an FPGA chip;

connecting an SDI pin of the processor with an SDO pin of the FPGA chip;

and connecting an SDO pin of the processor with an SDI pin of the FPGA chip.

In the TDM interface extension method, the control processor writes data into a sending buffer area and sequentially sends the data to an opposite end through the TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; the method for increasing the frequency of the clock signal and the frame synchronization signal of the TDM interface of the processor to be N times of the original frequency through the FPGA chip comprises the following steps:

one frame originally supported by the processor is made into subframes, and N subframes are transmitted in a sampling period of voice, wherein the sampling period of the voice is 8000HZ, namely, the sampling period of one voice is 125 us.

In the TDM interface extension method, the control processor writes data into a sending buffer area and sequentially sends the data to an opposite end through the TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; increasing the frequency of the clock signal and the frame synchronization signal of the TDM interface of the processor to the original N times through the FPGA chip further comprises:

n LRCK signals will be generated uniformly in time 1/8000 ═ 125us, while BCLK in N FS also becomes 256 × N; such a frame transfers 32 x N bytes of data.

The TDM interface extension method, wherein the step of increasing the frequency of the clock signal and the frame synchronization signal of the TDM interface of the processor to N times of the original frequency through the FPGA chip comprises the following steps:

providing a transmission capability of data by doubling the frequency of the TDM clock signal and the frame synchronization signal; adopting a signal format with N sub-frames in a large frame; the frequency of the clock signal and the frame synchronization signal of the TDM interface of the processor is increased to N times of the original frequency.

A TDM interface extension apparatus, wherein the apparatus comprises:

the system comprises a processor and an FPGA chip connected with the processor;

the first control module is used for controlling the TDM interface clock signal and the synchronous signal provided for the processor through the FPGA chip and realizing the time slot exchange function through the FPGA chip;

a second control module for controlling the processor to be initially configured to receive the clock signal and the synchronization signal of the FPGA from the mode;

the third control module is used for controlling the processor to write the data into the sending buffer area and sequentially sending the data to the opposite terminal through the TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; increasing the frequency of a clock signal and a frame synchronization signal of a TDM interface of the processor to be N times of the original frequency through the FPGA chip;

and the fourth control module is used for controlling the processor to apply for 2 DMA channels, wherein one DMA channel transmits the data of the memory of the processor to the sending buffer area, and the other DMA channel transmits the data of the receiving buffer area to the memory of the processor.

The TDM interface extension device is characterized in that,

a BCLK pin of the processor is connected with a BCLK pin of the FPGA chip;

an LRCK pin of the processor is connected with an LRCK pin of the FPGA chip;

an SDI pin of the processor is connected with an SDO pin of the FPGA chip;

and an SDO pin of the processor is connected with an SDI pin of the FPGA chip.

An apparatus comprising a memory and a processor, the memory storing a computer program, wherein the processor is externally connected to an FPGA chip, and the processor implements any of the method steps when executing the computer program.

A computer-readable storage medium, on which a computer program is stored, wherein the computer program realizes the steps of any of the methods when executed by a processor.

Compared with the prior art, the embodiment of the invention has the following advantages:

according to the method provided by the embodiment of the invention, the processor is externally connected with an FPGA chip; the TDM interface of the ARM processor is configured into a slave mode, a programmable logic control chip FPGA is additionally arranged outside the ARM processor to improve the frequency of a clock and a frame synchronization signal of the TDM interface provided for the ARM processor by N times, and therefore the data transmission capacity of the interface is improved by N times. According to the method and the device, one frame originally supported by the ARM processor is changed into the subframe, and N subframes are transmitted in a voice sampling period, so that the data transmission capacity of the TDM interface can be improved by N times. The sampling period of the voice is 8000HZ, i.e. one voice sampling period is 125 us. A rate of 32 x N slots, 2 x N M, can be supported by an inventive method. (N ═ 1,2,4,8, 16); and the function is not limited, the supported time slots are more, and the transmission rate is high.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic flow chart of a TDM interface extension method according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of an external FPGA chip of a processor a1000 according to the TDM interface extension method in the embodiment of the present invention;

fig. 3 is a schematic diagram of a TDM interface for processor a 1000.

Fig. 4 is a diagram illustrating a structure of a TDM interface of a processor a1000 according to the prior art with limited processing capability.

Fig. 5 is a schematic diagram of the operation of a TDM interface of a processor a1000 according to the prior art without an extension.

Fig. 6 is a schematic diagram of a TDM interface operation according to an embodiment of the present invention.

Fig. 7 is a functional block diagram of a TDM interface extension apparatus according to an embodiment of the present invention.

FIG. 8 is a functional block diagram of an apparatus according to an embodiment of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the embodiment of the invention, the processor can be a full-log ARM processor A1000; the processor of global record H8 and ARM chip of global record can be supported by the processor with the tdm interface opened. The processor is exemplified as a full-featured ARM processor A1000.

The inventor has found that, as shown in fig. 4, the TDM interface of the existing full-log ARM processor a1000 supports the TDM interface, and as shown in fig. 4, the TDM interface of the processor a1000 has limited processing capability, as can be seen from fig. 4, there are 8 slots in the processor a1000 for one FS, each slot transmits 4 bytes, and in total, one FS can transmit 4 × 8 — 32 bytes. The TDM interface of a1000 has only the transmission capacity of 2M 32 slots at maximum before doing no extension work. The operation diagram of the TDM interface is shown in fig. 5, so that the function of this interface of the ARM processor a1000 in the prior art is limited, and only 32 timeslots can be supported, the rate of 2M is supported, and the transmission rate is not high.

In order to solve the above problem, in the embodiment of the present invention, an extending method of a TDM interface is provided, and as shown in fig. 1 and fig. 2, an FPGA chip is externally connected to a processor, and the TDM clock signal and the frame synchronization signal are doubled in frequency to provide data transmission capability. Here the signal format of N subframes in a large frame is different from the existing frame format, so that it can support a rate of 32 × N slots, 2 × N M. (N ═ 1,2,4,8, 16).

Various non-limiting embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Referring to fig. 1, fig. 1 shows a TDM interface extension method in an embodiment of the present invention, where the method includes:

s1, externally connecting the processor A1000 with an FPGA chip;

in the embodiment, the processor a1000 is externally connected to an FPGA chip, and as shown in fig. 2, the BCLK pin of the processor a1000 is connected to the BCLK pin of the FPGA chip; connecting an LRCK pin of the processor A1000 with an LRCK pin of an FPGA chip; connecting an SDI pin of the processor A1000 with an SDO pin of the FPGA chip; and connecting the SDO pin of the processor A1000 with the SDI pin of the FPGA chip.

Wherein TDM interface introduction of processor a1000 referring to fig. 3, the APB bus is a peripheral bus. The synchronizer is respectively connected with the 64 x 32 bit receiving buffer and the 128 x 32 bit sending buffer, and is also connected with the multiplexer through an integrated circuit built-in audio bus engine; the synchronizer is connected with the pulse code modulation encoder and then connected with the multiplexer through the pulse code modulation engine, and the multiplexer is connected with the clock frequency divider; and a BCLK (serial clock) pin, an LRCK (frame synchronization clock) pin, an SDO (data output) pin, and an SDI (data input) pin are connected.

In a specific embodiment, the present invention controls processor a1000 to apply for 2 DMA channels, one DMA channel to transfer data from the memory of processor a1000 to the send buffer, and another DMA channel to transfer data from the receive buffer to the memory of processor a 1000.

And S2, controlling to provide TDM interface clock signals and synchronous signals for the processor A1000 through the FPGA chip, and realizing the time slot exchange function through the FPGA chip.

S3, control processor A1000 is initially configured to receive clock signals and synchronization signals for the FPGA from the mode.

S4, the control processor A1000 writes the data into the sending buffer area and sends the data to the opposite end in sequence through the TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; the frequencies of the clock signal and the frame synchronization signal of the TDM interface of the processor a1000 are increased to N times of the original frequencies by the FPGA chip.

Specifically, as shown in fig. 2, in the present invention, an FPGA is added to a1000, and the FPGA chip increases BCLK and LRCK by N times of the original values.

As shown in fig. 6, N LRCK signals will be generated uniformly in time 1/8000 ═ 125us, while BCLK in N FS also becomes 256 × N; such a frame transfers 32 x N bytes of data.

The software function of the invention is that the FPGA provides a clock and a synchronous signal of a TDM interface for A1000 and also needs to realize the exchange function of time slots; a1000 is initially to be configured to receive clock and synchronization signals of the FPGA from a mode; data transfer may be from adapter card to Memory, from Memory to adapter card, or from one section of Memory to another section of Memory, with one DMA channel transferring data from a1000 Memory to TX FIFO and another DMA channel transferring RX FIFO to a1000 Memory.

The present invention optionally makes one frame originally supported by processor a1000 into subframes, and transmits N subframes in a sampling period of speech, which is 8000HZ, i.e. 125us of a speech sampling period. Providing a transmission capability of data by doubling the frequency of the TDM clock signal and the frame synchronization signal; adopting a signal format with N sub-frames in a large frame; the frequencies of the clock signal and the frame synchronization signal of the TDM interface of the processor a1000 are increased to N times as much as the original frequencies.

Therefore, according to the method for extending the TDM interface in the embodiment of the present application, the implementation rule that only 32 timeslots are provided for one frame of the ARM processor a1000 is observed, the TDM interface of the ARM processor a1000 is configured as the slave mode, and a programmable logic control chip FPGA is added outside the ARM processor a1000 to increase the frequencies of the clock and the frame synchronization signal provided to the TDM interface of the ARM processor a1000 by N times, so that the data transmission capability of the interface is increased by N times. According to the method, one frame originally supported by the ARM processor A1000 is changed into a subframe, and N subframes are transmitted in a voice sampling period, so that the data transmission capacity of the TDM interface can be improved by N times. The sampling period of the voice is 8000HZ, i.e. one voice sampling period is 125 us. A rate of 32 x N slots, 2 x N M, can be supported by an inventive method. (N ═ 1,2,4,8, 16); and the function is not limited, the supported time slots are more, and the transmission rate is high.

In one embodiment, the present invention provides a TDM interface extension apparatus, as shown in fig. 7, the apparatus including:

the system comprises a processor and an FPGA chip connected with the processor;

the first control module 71 is configured to control the processor to provide a TDM interface clock signal and a synchronization signal through the FPGA chip, and implement a time slot switching function through the FPGA chip;

a second control module 72 for controlling the processor to be initially configured to receive clock signals and synchronization signals of the FPGA from the mode;

a third control module 73, configured to control the processor to write data into the sending buffer, and sequentially send the data to an opposite end through the TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; increasing the frequency of a clock signal and a frame synchronization signal of a TDM interface of the processor to be N times of the original frequency through the FPGA chip;

a fourth control module 74, configured to control the processor to apply for 2 DMA channels, where one DMA channel transmits data in the memory of the processor to the sending buffer, and the other DMA channel transmits data in the receiving buffer to the memory of the processor; as described above.

In the TDM interface expansion device, the processor adopts a processor a1000, and a BCLK pin of the processor a1000 is connected with a BCLK pin of the FPGA chip;

an LRCK pin of the processor A1000 is connected with an LRCK pin of the FPGA chip;

an SDI pin of the processor A1000 is connected with an SDO pin of the FPGA chip;

an SDO pin of the processor A1000 is connected with an SDI pin of the FPGA chip; as described above.

In one embodiment, the present invention provides an apparatus, which may be a terminal, having an internal structure as shown in fig. 8. The apparatus includes a processor, a memory, a network interface, a display screen, and an input device connected by a system bus. Wherein the processor of the device is configured to provide computing and control capabilities. The memory of the device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The network interface of the device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a method of generating a natural language model. The display screen of the equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the equipment, an external keyboard, a touch pad or a mouse and the like.

Those skilled in the art will appreciate that fig. 8 is a block diagram of only a portion of the structure associated with the disclosed aspects and is not intended to limit the devices to which the disclosed aspects apply, and that a particular device may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.

The embodiment of the invention provides equipment, which comprises a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to realize the following steps:

externally connecting the processor with an FPGA chip;

controlling to provide a TDM interface clock signal and a synchronous signal for the processor through the FPGA chip, and realizing the exchange function of time slots through the FPGA chip;

the control processor is initially configured to receive a clock signal and a synchronization signal of the FPGA from the mode;

the control processor writes the data into a sending buffer area and sequentially sends the data to an opposite terminal through a TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; the frequency of a clock signal and a frame synchronization signal of a TDM interface of the processor is increased to be N times of the original frequency through the FPGA chip.

An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the following steps:

externally connecting the processor with an FPGA chip;

controlling to provide a TDM interface clock signal and a synchronous signal for the processor through the FPGA chip, and realizing the exchange function of time slots through the FPGA chip;

the control processor is initially configured to receive a clock signal and a synchronization signal of the FPGA from the mode;

the control processor writes the data into a sending buffer area and sequentially sends the data to an opposite terminal through a TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; the frequency of a clock signal and a frame synchronization signal of a TDM interface of the processor is increased to be N times of the original frequency through the FPGA chip.

In summary, compared with the prior art, the embodiment of the invention has the following advantages:

according to the TDM interface extension method, the TDM interface extension device, the TDM interface extension equipment and the readable storage medium, the method connects a processor A1000 with an FPGA chip; controlling to provide a TDM interface clock signal and a synchronous signal for the processor A1000 through an FPGA chip and realizing the exchange function of time slots through the FPGA chip; control processor A1000 is initially configured to receive clock signals and synchronization signals for the FPGA from the mode; the control processor A1000 writes data into a sending buffer area and sequentially sends the data to an opposite end through a TDM interface; the data of the opposite terminal is sequentially stored in a receiving buffer area through a TDM interface; increasing the frequency of a clock signal and a frame synchronization signal of a TDM interface of the processor A1000 to N times of the original frequency through an FPGA chip; and the function is not limited, the supported time slots are more, and the transmission rate is high.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.