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A FreeRTOS BSP for the Xilinx SDK
IntroductionThe Xilinx Software Development Kit (SDK) can automatically generate a board support package from a hardware definition file. The board support package provides comprehensive run time, processor and peripheral support. It is also possible for the BSP to include the FreeRTOS real time operating system.
Including FreeRTOS in the BSP presents the application writer with a pre-configured FreeRTOS environment that does not require any source files to be added manually, any callback functions to be provided by the application code, and allows FreeRTOSConfig.h to be edited within the IDE.
Instructions for creating a FreeRTOS BSP are provided below. The FreeRTOS download also includes separate and comprehensive demo applications for the Xilinx Zynq dual core ARM Cortex-A9 processor, an ARM Cortex-A53 core on the UltraScale+ MPSoC (64-bit), an ARM Cortex-R5 core on the the UltraScale+ MPSoC (32-bit), and Xilinx Microblaze soft-core processors. Those comprehensive demo applications, as provided in the the FreeRTOS download, use a standalone BSP. A standalone BSP does not itself include FreeRTOS, so FreeRTOS is instead built as part of the application. It is still important to read the documentation pages for those standalone demos, even when a FreeRTOS BSP is being used, as the pages provide information on how to use FreeRTOS on those ARM and Xilinx architectures.
Creating a Hello World Project That Uses the FreeRTOS BSPThe board support package (BSP) repositories that ship as part of the Xilinx SDK come with a simple FreeRTOS hello world application. The hello world project is created as follows:
Select “New: Application Project” from the SDK’s “File” menu to bring up
the new project Window, then give the project a name.
The “New: Application Project” menu option
In the new project window – first select the hardware platform in use.
Pre-defined hardware platforms are provided for all the processors supported
by FreeRTOS (Zynq ARM Cortex-A9, UltraScale+ ARM Cortex-A53 and ARM Cortex-A9
cores, and Microblaze). The image below shows the pre-configured ZC702
platform being used.
After the hardware platform has been selected, select the processor. The
image below shows the ps7_cortexa9_0 processor selected.
After the processor has been selected, select the OS Platform. The
image below shows freertos822 selected.
Defining the project settings
Click the “Next” button to move onto the next stage. The Templates
Window will appear – select the “FreeRTOS Hello World” template, then
click the “Finish” button to generate both the FreeRTOS BSP and the
Hello World project.
Selecting the FreeRTOS Hello World template
Editing the FreeRTOS ConfigurationA FreeRTOSConfig.h file was automatically created when the FreeRTOS BSP was generated. The values contained in the file can be viewed, and edited, using the following procedure:
Select “Board Support Package Settings” from the “Xilinx Tools” menu
in the SDK. The Board Support Package Settings window will appear.
Select FreeRTOS in the left pane of the Board Support Package Settings
window. The table in the right pane will populate with the FreeRTOSConfig.h
Edit the settings as necessary, then click the “Ok” button to update
FreeRTOSConfig.h with the edited values, and re-build the BSP.
Starting a Debug SessionIt is therefore necessary to ensure the SDK launch configurations used to start a debug session resets the entire CPU, and runs the necessary initialisation scripts. A debug configuration suitable for running the Zynq demo is shown in the image below.