CN115550568A - Image transmission method and system based on CoaXpress protocol - Google Patents

Abstract

The invention discloses an image transmission method and system based on a CoaXpress protocol in the field of image transmission, wherein the method comprises the following steps: acquiring image data, writing the image data into an image framing process to obtain an image signal, and transmitting the image signal to a CoaXpress interface through link arbitration and a high-frequency link PHY; the image framing processing comprises writing image data into a multi-channel transmission, checking the image data, finishing image data caching, and obtaining image data which can be read through a standard interface; and dividing the image data which can be read through the standard interface into a multi-link channel, and framing the image data which meets the CoaXpress protocol to obtain the image signal. The invention can adapt to various CoaXpress link speeds and the parallel transmission of a plurality of links, thereby greatly widening the data bandwidth.

Description

Image transmission method and system based on CoaXpress protocol

Technical Field

The invention relates to the field of image transmission, in particular to an image transmission method and system based on a CoaXpress protocol.

Background

The industrial camera is a core component of machine vision, and with the development of science and technology, some demands for high-speed and high-precision machine vision detection have made higher and higher requirements on the resolution and frame rate of the industrial camera, so that higher data bandwidth is also required to transmit images. Under the requirement of high transmission speed, interfaces such as USB, ethernet interface, camera Link and CoaXpress can be generally adopted between the Camera and the computer for data transmission.

USB and Ethernet protocols are integrated in the existing standard computer structure, and when the two interfaces are used, the CPU bandwidth is additionally occupied to process image data transmission; when high-speed image data transmission is performed, a large amount of CPU load is required, resulting in a reduction in the ability of the CPU to process other transactions. Meanwhile, the bandwidths of the USB and the Ethernet are relatively small, and the USB and the Ethernet are not suitable for camera transmission with high resolution and high frame rate.

Camera Link is a standard for high resolution and high frame rate transmission, but the maximum transmission rate of Camera Link is 850MB/s, which is much lower than CoaXpress. Meanwhile, the Camera Link needs to use different parallel transmission channels, so that the required wires are very thick and heavy, have poor flexibility and are expensive. Furthermore, the wire can only reach a maximum of 10 meters. And the transmission based on the CoaXpress protocol needs to be additionally provided with an additional expansion card, so that data transmission and processing can be carried out in the expansion card, and the load of a CPU (central processing unit) is saved.

Under the background, the invention realizes an image transmission method and system in the industrial camera using the CoaXpress interface, can fully utilize the advantages of the CoaXpress protocol, and realizes the data transmission of the CoaXpress protocol at the camera end.

Disclosure of Invention

The present invention provides an image transmission method and system based on CoaXpress protocol to solve the problems in the background art.

In order to achieve the purpose, the invention provides the following technical scheme:

an image transmission method based on a CoaXpress protocol comprises the following steps:

acquiring image data, writing the image data into an image framing process to obtain an image signal, and transmitting the image signal to a CoaXpress interface through link arbitration and a high-frequency link PHY;

the image framing processing comprises writing image data into a multi-channel transmission, checking the image data, finishing image data caching, and obtaining image data which can be read through a standard interface; and dividing the image data which can be read through the standard interface into a multi-link channel, and framing the image data which meets the CoaXpress protocol to obtain the image signal.

Further, the image data checking is performed to complete the image data caching, and the method includes:

carrying out data integrity detection on the image data transmitted by the multiple channels, carrying out data control and caching on the detected complete data, wherein the cached image data can be read through a standard interface;

the sequence of detecting the complete data written into the cache is set based on the detection result of the data integrity detection, and multiple transmission modes of the data are supported.

Further, the data control includes: when the length of the data line is detected to be incomplete, discarding the current line; after buffering the complete line data, the buffered image data is allowed to be read through the standard interface.

Further, the framing that satisfies the CoaXpress protocol includes:

and detecting the length of the data transmitted by the multi-link channel, and after the length of the data meets the set length of a CoaXpress protocol, adding specific information at the initial position of a frame to perform data framing to obtain an image signal.

Furthermore, the data interfaces of the image framing processing, the link arbitration and the high-frequency link PHY adopt the same standard interface.

Furthermore, the image transmission method based on the CoaXpress protocol is compatible with switching of multiple transmission speeds through link dynamic configuration.

An image transmission system based on the CoaXpress protocol, comprising:

the image framing module writes image data into multi-channel transmission, performs image data inspection, completes image data caching and obtains image data which can be read through a standard interface; dividing the image data which can be read through the standard interface into a multi-link channel, and framing meeting a CoaXpress protocol to obtain the image signal;

the link arbitration module is used for sequencing the sent signals according to priority and transmitting the signals to the high-frequency link PHY module;

and the high-frequency link PHY module outputs a high-frequency signal to the CoaXpress interface.

Has the advantages that: in the prior art, the Camera adopting the USB protocol, the Ethernet protocol and the Camera Link protocol has limited bandwidth, and the Camera based on the CoaXpress protocol has extremely high bandwidth advantage. The image transmission method in the invention can adapt to various CoaXpress link speeds and the parallel transmission of a plurality of links, thereby greatly widening the data bandwidth.

Drawings

FIG. 1 is a block diagram of an image transmission structure based on CoaXpress protocol according to the present invention;

FIG. 2 is a diagram illustrating decoding of original image data according to the present invention;

FIG. 3 is a block diagram of a frame image data buffer according to the present invention;

FIG. 4 is a block diagram of the present invention for framing frame image data according to the CoaXpress protocol.

Detailed Description

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.

Referring to fig. 1, an image transmission system based on the CoaXpress (CXP) protocol includes an image framing module, a link arbitration module, and a high frequency link PHY module. Based on the image transmission system, the image transmission method comprises the following steps:

the FPGA receives the low-frequency signal and the original image data and sends a high-frequency signal. The low frequency signal has a rate of 20.83Mbps or 41.66Mbps, and the high frequency signal has a rate of 1.25Gbps, 2.5Gbps, 3.125Gbps, 6.25Gbps, 10Gbps, 12.5Gbps, and the like.

In the FPGA, a low-frequency signal is converted into a 10-Bit parallel data stream through a serial-parallel conversion module, the serial-parallel conversion module adopts a low-frequency clock signal recovered by a CoaXpress interface chip as a working clock, and effective 10-Bit parallel data are output every 10 clock cycles. And the serial-parallel conversion module has the function of shifting 10bit parallel data streams and can shift according to the setting of the calibration module. And the parallel data stream converted by the serial-parallel conversion module is decoded by a 10B/8B decoding module, so that correct 8-bit low-frequency signal data is obtained. The calibration module adjusts the data output of the serial-parallel conversion module according to the feedback information of the 10B/8B decoding module, so that a correct 10-bit data boundary is found, and correct 10B/8B decoding is realized.

The decoding module decodes the parallel data to obtain low-frequency signal data, the low-frequency signal data comprises various different information such as trigger information, control information and the like, the trigger information is sent to a trigger module in the FPGA, and an external trigger signal is generated and sent to the outside; the control information is written into an MCU (micro control unit) through a write register (RX buffer), then the MCU analyzes the received control information according to a standard CXP protocol to control the state of the camera, and the MCU sends the processed information to a link arbitration module through a read register (TX buffer) and waits for a high-frequency link to send.

In addition, the link arbitration module also receives the image signal, the trigger ACK signal generated by the trigger ACK module and the heartbeat signal generated by the heartbeat module, and the link arbitration module transmits the received data sequentially through the high-frequency link PHY module according to the priority order.

Specifically, referring to fig. 2, the original image data is decoded into standard image data, i.e. the standard data protocol interface can write the received data. Standard data protocol interfaces include the following write interfaces: sof (start of frame), eof (end of frame), sol (start of line), eol (end of line), dvld (data valid), data (data). The original image data is decoded and converted into the image data of the interface, and the image data of the interface is received by the FPGA. The image framing module writes image data into a multi-channel for transmission, performs image data inspection, completes image data caching and obtains image data which can be read through a standard interface; the image data which can be read through the standard interface is divided into multi-link channels, framing which meets the CoaXpress protocol is carried out, and image signals are obtained.

The method for framing the image data of the interface by the image framing module according to the CoaXpress protocol comprises the following steps:

as shown in fig. 3, the image data of the interface is written into a first-in first-out channel (channel FIFO) of a data buffer (packet buffer) through a write interface (write interface) for buffering.

The data buffer has a plurality of channels such as channel 0FIFO (channel 0 FIFO), channel 1FIFO (channel 1 FIFO) \8230andchannel N FIFO (channel N FIFO), and thus can support multi-channel transmission. In the process of buffering the image data in the channel FIFO, a data selector (MUX) in the data buffer simultaneously detects the integrity of the frame image data, such as the length of a data line, the width of a data frame, and the like, and continuously feeds back the detected information to a preset write schedule (write schedule) policy, wherein the write schedule policy determines the sequence of writing the image data of different channels into a main buffer. According to different write scheduler strategies, multi-data transmission can be supported.

When detecting the image data, a packet management (packet management) module performs data control on the image data written into the main cache, and when detecting that the length of a data line is incomplete, the current line is discarded; when the complete row data is stored in the main cache, the read interface (read interface) is allowed to read the current cache (buffer), thereby ensuring the validity and the integrity of the row data. By the method, when the decoding speed of the original image data is low, the follow-up CXP-protocol-based data transmission can still keep efficient transmission, and when the data generated at the decoding speed is higher than the bandwidth of the CXP protocol, the integrity of the data transmission of the current line can be ensured by discarding the line data.

The read data interface of the main cache adopts a standard AXI-Stream interface, AXIs _ tlast represents an eol signal, and AXIs _ tuser represents a frame valid signal. The subsequent processing modules (packet splitter, link arbitration, PHY module, etc.) also adopt AXI-Stream standard interfaces, which facilitates the interconnection of the subsequent modules.

The image data in the main buffer is read by a packet splitter (packet splitter), and is divided according to the number of link channels according to a preset length. As shown in fig. 4, taking 4 links as an example, the image data is divided into 4 packets and distributed to 4 link channels. In other embodiments, other different numbers of links may be employed.

The whole image data after screening is stored in the main buffer, but the CXP transmitted data needs to add some data required by the protocol at the beginning and end of the data frame in addition to the image data. Therefore, the packing module (packer) continuously detects the data in the buffer, and when the data reaches the set length of CXP, framing is carried out. Specifically, specific mark (Line Marker) information, that is, data specified by the CXP protocol is added at the frame start position so as to conform to the CXP protocol.

After signal arbitration is carried out on the framed data, the trigger ACK signal, the heartbeat signal and the like through the link arbitration module, the framed data, the trigger ACK signal, the heartbeat signal and the like are sequentially sent to the high-frequency link PHY module according to the priority order for data transmission, and the high-frequency link PHY module outputs a high-frequency signal. In addition, according to the specification of the CXP protocol, the method also sends Header (Header) information periodically through a Header generator (Header generator), and the Header information is transmitted through the channel 0.

In addition, in the former framing mode, the main buffer part will buffer data, and when the CXP rate is fast and the image data is slow, the main buffer will wait until enough data is buffered, and then start to transmit the image data; when the CXP rate is slow but the image data is fast, the main buffer discards the currently received data to ensure that the data already stored in the main buffer is complete. Therefore, the image transmission method based on the CoaXpress protocol is compatible with various link speeds, and the PHY link speed and the system clock speed can be dynamically configured through the DRP, so that the switching of various speeds including 1.25Gbps, 2.5Gbps, 3.125Gbps, 6.25Gbps, 10Gbps, 12.5Gbps and the like can be realized.

The invention has at least the following advantages:

1. the data written into the main cache by different channels can be controlled according to different write scheduler strategies, so that different transmission modes can be supported;

2. the integrity check of the main buffer data frame can be carried out, the speed matching of the image rate and the CXP rate can be ensured, and the support to different CXP link speeds is ensured;

3. the data interface of the main buffer adopts a standard AXI-Stream interface, so that the interconnection of subsequent processing modules is ensured.

Although the present description is described in terms of embodiments, not every embodiment includes only a single embodiment, and such description is for clarity only, and those skilled in the art should be able to integrate the description as a whole, and the embodiments can be appropriately combined to form other embodiments as will be understood by those skilled in the art.

Therefore, the above description is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application; all the equivalent changes made within the scope of the claims of the present application are the protection scope of the claims of the present application.

Claims (7)

1. An image transmission method based on a CoaXpress protocol is characterized by comprising the following steps:

acquiring image data, writing the image data into an image framing process to obtain an image signal, and transmitting the image signal to a CoaXpress interface through link arbitration and a high-frequency link PHY;

the image framing processing comprises the steps of writing image data into a multi-channel transmission, checking the image data, finishing image data caching, and obtaining image data which can be read through a standard interface; and dividing the image data which can be read through the standard interface into a multi-link channel, and framing the image data meeting the CoaXpress protocol to obtain the image signal.

2. The method according to claim 1, wherein the step of performing image data inspection to complete image data caching comprises:

carrying out data integrity detection on the image data transmitted by the multiple channels, carrying out data control and caching on the detected complete data, wherein the cached image data can be read through a standard interface;

the sequence of detecting the complete data written into the cache is set based on the detection result of the data integrity detection, and multiple transmission modes of the data are supported.

3. The method for transmitting an image based on a CoaXpress protocol according to claim 2, wherein the data control comprises: when the length of the data line is detected to be incomplete, discarding the current line; after buffering the complete line data, the buffered image data is allowed to be read through the standard interface.

4. The method according to claim 1, wherein the framing that satisfies the CoaXpress protocol comprises:

and detecting the length of the data transmitted by the multi-link channel, adding specific information at the frame starting position after the length of the data meets the set length of a CoaXpress protocol, and framing the data to obtain an image signal.

5. The method according to claim 1, wherein the data interfaces of the image framing processing, the link arbitration and the high frequency link PHY adopt the same standard interface.

6. The image transmission method based on the CoaXpress protocol as claimed in claim 1, wherein the image transmission method based on the CoaXpress protocol is compatible with switching of a plurality of transmission speeds through link dynamic configuration.

7. An image transmission system based on the CoaXpress protocol, comprising:

the image framing module writes image data into multi-channel transmission, performs image data inspection, completes image data caching and obtains image data which can be read through a standard interface; dividing the image data which can be read through the standard interface into a multi-link channel, and framing the image data which meets the CoaXpress protocol to obtain the image signal;

the link arbitration module is used for sequencing the transmitted signals according to the priority and transmitting the signals to the high-frequency link PHY module;

and the high-frequency link PHY module outputs a high-frequency signal to the CoaXpress interface.

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