FreeRTOS ported to ARM Versatile Platform Baseboard, based on the ARM926EJ-S CPU.
The current version is based on FreeRTOS 10.5.1+. The port will be regularly updated with newer versions of FreeRTOS when they are released.
The port is still at an early development stage and includes only very basic demo tasks. More complex tasks will be included in the future.
- GNU Arm Embedded Toolchain, based on GCC. See comments in setenv.sh for more details about download and installation.
- GNU Make
- Qemu
On Debian or Ubuntu you should be ready to go with:
sudo apt install gcc-arm-none-eabi make qemu-system-arm
A convenience Bash script setenv.sh is provided to set paths to toolchain's commands and libraries. You may edit it and adjust the paths according to your setup. To set up the necessary paths, simply type:
. setenv.sh
If you wish to run the image anywhere else except in Qemu, you will probably have to edit the linker script qemu.ld and adjust the startup address properly.
To build the image with the test application, just run make or make rebuild. If the build process is successful, the image file image.bin will be ready to boot.
You can edit the Makefile and set USE_NEWLIB=1 if you want to link against a full libc for a bigger project using more C-functions from the standard library.
To run the target image in Qemu, enter the following command ('Ctrl-A x' to exit qemu):
qemu-system-arm -M versatilepb -nographic -m 128 -kernel image.bin
Or more conveniently:
make run
A convenience Bash script start_qemu.sh is provided. If necessary, you may edit it and adjust paths to Qemu and/or target image.
The demo application will run infinitely so it must be stopped manually by "killing" the instance of Qemu (an "equivalent" to switching off the board). A convenience Bash script stop_qemu.sh (it must be run in another shell) is provided to automate the process. Note that it may not work properly if multiple instances of qemu-system-arm are running. You can also just execute killall qemu-system-arm in another shell to stop all qemu instances.
For more details, see extensive comments in both scripts.
To check the size of the compiled image, you can look at:
arm-none-eabi-size image.elf
Or the size of the individual object files:
arm-none-eabi-size obj/*.o | sort -n
To look at the generated assembler output, you can look at (also stored into the file "image.lst"):
arm-none-eabi-objdump -d image.elf
See also qemu.ld to check the RAM layout:
| start | end | size | description |
|---|---|---|---|
| 0x000000 | 0x00003F | 64 bytes | vectors (8 vectors and 8 offset values to branch to) |
| 0x000040 | 0x00103F | 4K bytes | stack for supervisor (SVC) mode |
| 0x001040 | 0x00203F | 4K bytes | stack for IRQ mode |
| 0x002040 | 0x00FFFF | 64 kB - 8 kB - 64 bytes | stack for system mode (less than 56 kB) |
| 0x010000 | 0x01003F | 64 bytes | vectors as part of the binary image |
| 0x010040 | 0x?????? | text and data of the binary image | |
| 0x?????? | 0x?????? | bss data, set to 0 on bootup | |
| 0x?????? | 0x?????? | heap (uses up to 128 MB of the remaining available RAM) |
- Add more hardware support within qemu possibilities.
- Add more demo/test code.
- Timer functions could be inlined?
- Small/fast timer interrupt handling.
- Is it possible to write startup code as C with inline assembler?
- Support using clang instead of gcc.
- Can we run on Windows?
All source and header files are licensed under the MIT license.
For the avoidance of any doubt refer to the comment included at the top of each source and header file for license and copyright information.