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1. PCIe communication between Rockchip RK3568J and FPGA
What are the advantages of ARM + FPGA architecture
In recent years, with the continuous advancement of China's new infrastructure and Made in China 2025, it has become increasingly difficult for a single ARM processor to meet the functional requirements of industrial sites, especially in industries such as energy and power, industrial control, and smart medical care, which usually require ARM + FPGA architecture. Processor platform to realize specific functions, such as multi-channel/high-speed AD acquisition, multi-channel network port, multi-channel serial port, multi-channel/high-speed parallel DI/DO, high-speed data parallel processing, etc.
What are the advantages of the ARM + FPGA architecture?
ARM: Rich interface resources, low power consumption, good at multimedia display, logic control, etc.
FPGA: Good at multi-channel or high-speed AD acquisition, interface expansion, high-speed signal transmission, high-speed data parallel processing, etc.
Therefore, the ARM + FPGA architecture can bring comprehensive comparative advantages such as performance and power consumption. ARM and FPGA can perform their own duties and give full play to the unique advantages of the original architecture, and they can also cooperate with each other to deal with more complex problems.
Why ARM + FPGA high-speed communication is needed
In industrial application scenarios, generally FPGA is used as the front end of data acquisition, and there is often a large amount of data that needs to be transmitted to ARM for processing. Such as energy and electricity, FPGA will be used as high-speed AD or multi-channel AD acquisition, and then a large amount of generated data will be transmitted to ARM for AD data storage and processing; another example is smart medical care, FPGA needs to transmit the collected and processed high-definition video data to ARM , allowing ARM to perform video display, encoding or storage of high-speed video data. Therefore, "ARM + FPGA high-speed communication" is a key factor for the success of the "ARM + FPGA architecture" project.
In order to meet the growing localization needs of industries such as energy and electricity, smart medical care, and rail transit, Chuanglong Technology took the lead in launching the RK3568J industrial core board with a 100% localization rate , and provided high-speed communication cases based on RK3568J and FPGA .
RK3568J + FPGA high-speed communication case
The following will introduce the PCIe high-speed communication case based on Rockchip RK3568J (hardware platform: Chuanglong Technology TL3568-EVM evaluation board) and Xilinx Artix-7 (hardware platform: Chuanglong Technology TLA7-EVM evaluation board) .
The ARM side performs read and write tests on the FPGA BRAM based on the PCIe bus. After the application sends a command through the ioctl function to enable DMA transfer data, it waits for the driver to report the input event; when the application layer receives the input event, it means that the DMA transfer data is completed.
In terms of hardware construction, use the M.2 Key M to PCI-E 4X extension cable to connect the M.2 PCIe NVMe interface of the TL3568-EVM evaluation board to the PCIe interface of the TLA7-EVM evaluation board of Chuanglong Technology, and evaluate the TLA7-EVM The board is connected to the PC through the TL-DLC10 downloader, and the hardware connection is shown in the figure below. 
Figure 1 Schematic diagram of hardware construction
According to the case user manual provided by Chuanglong Technology, we obtained the actual measurement data of ARM and FPGA based on PCIe communication, as shown in the figure below. The measured DMA transfer rate of the write operation is 780.77MB/s, and the DMA transfer rate of the read operation is 563.06MB/s. 
Fig. 2 Data measurement 
Fig. 3 Data interpretation