Compiling the library for Raspberry Pi Pico

Question

Compiling the library for Raspberry Pi Pico

secureshadow opened this issue 8 months ago · 11 comments

Hello,

I am interested in developing CSP inside freeRTOS on my raspberry pi pico. The main problem I encounter is that this board, does not have a way to access it via ssh or to its command terminal to compile the library into this structure.

The main information I found was that I needed to crosscompile the code using gcc-arm-none-eabi, but the toolchain.cmake file does not appear to be working or it is not provided.

Do you have any recommendation on how to compile your library for ARM CortexM0+ MCUs? It will be appreciated. If you have the library already precompiled it will be good too.

This is my current pico-toolchain.cmake

set(CMAKE_SYSTEM_NAME Generic)
set(CMAKE_C_COMPILER /usr/bin/arm-none-eabi-gcc)
set(CMAKE_CXX_COMPILER /usr/bin/arm-none-eabi-g++)
set(CMAKE_SYSTEM_PROCESSOR cortex-m0plus)
set(PICO_SDK_PATH "/home/vladik/Documentos/pico/pico-sdk") 
set(TOOLCHAIN_PREFIX arm-none-eabi-)
set(CMAKE_FIND_ROOT_PATH ${PICO_SDK_PATH})
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

And I am building using this command

mkdir build
cd build
cmake -DCMAKE_TOOLCHAIN_FILE=../pico-toolchain.cmake ..
make

Thank you in advance!

Answer 1 · 2023-11-09T21:40:53.000Z

Hi,

I don't use FreeRTOS but it might be better to use Meson to build libcsp against FreeRTOS. CMake support was started to integrate libcsp with Zephyr RTOS. And I personally build libcsp with CMake against Zephyr and Linux.

OTOH, we have a sample repo to build libcsp against FreeRTOS with Meson and this repo is used to test libcsp for every PR. You can find build reports under GitHub Actions, such as https://github.com/libcsp/libcsp/actions/runs/6812949903/job/18526453876.

Hope this helps.

Answer 2 · 2023-11-09T22:01:34.000Z

BTW, Raspberry Pi Pico is also supported by Zephyr RTOS. And this is how you use it.

Answer 3 · 2023-11-10T08:40:22.000Z

Hello,

Thank you for your fast response! I am using the raspberry pi pico just as a check to to develop a bit with CSP, because I will later implement it in my university CubeSat which will probably use an ARM MCU architecture, so that is why I am interested into compiling the library for this architecture to see how it works.

The main objective for me is developing CSP with freeRTOS on an ARM MCU.
My project structure looks like this:

I would like to compile the CSP library for ARM architectures and then link the header files in my project's CMakeLists.txt file. Even if I use Meson or CMake I will need a toolchain.cmake file to crosscompile the code correctly, because I cannot acces to the device's terminal to execute it inside its processor.

Any feedback is welcomed!

Answer 4 · 2023-11-10T08:51:55.000Z

Did you try https://github.com/libcsp/libcsp-freertos ?

Answer 5 · 2023-11-10T09:16:08.000Z

Yes, I have tried. The main issue for me, is that the freeRTOS kernel in that repository is not the one specific for my project (that can be solved easily), but the problem comes with the meson.build file, this file builds for my computer architecture, and not for the ARM M0+ MCU, so I will need either way a toolchain.txt file to tell meson compiler that instead of compiling for my computer architecture x86, it will need to do it using the gcc-arm-none-eabi compiler.
If this is sucessfull, it will generate the .u2f files to upload to my board's MCU. I am missing this toolchain file to tell the compiler to build for another MCU architecture.

I am wondering how other cubesats that use embbeded MCUs managed to make it.

Answer 6 · 2023-11-10T11:16:52.000Z

Ok. In that case, you have two ways

Port libcsp Meson to your architecture

As you already know, you have to provide a file, my-cortex-m0.txt, for cross compilation. And do

meson setup --cross-file my-cortex-m0.txt builddir
meson compile -C builddir

I'm sure this one is easier than latter.

Ref) https://mesonbuild.com/Cross-compilation.html

Port libcsp CMake to FreeRTOS

Make sure you can build any sample, i.e blinky, against FreeRTOS for your archtecture.
- For RPi Pico:
  - https://www.google.com/search?q=build+freertos+for+raspberry+pi+pico
  - Many seem to be using Pico SDK.
Integrate libcsp into your build env. (But this should fail because libcsp's CMake doesn't support FreeRTOS right now)
Add FreeRTOS support to all of the libcsp's CMakeLists.txt files. (Search for "Linux" or "Zephyr"; that's where you need to add FreeRTOS support).

Hope this helps.

Answer 7 · 2023-11-12T15:44:55.000Z

I am trying to build the library using Meson as sugegsted. I have created a simple project to test it. This is the project structure:

vladik@vladik: /Documentos/pico/testing$ ls
a.out  builddir  cross_file.txt  libcsp  main.c  meson.build

As you can see, I have made first a meson.build file for my project with the following content:

project('my_project', 'c')
executable('my_program', 'main.c')

I have also created a cross_file.txt file to cross compile this main.c file into the RP2040 MCU and configured as follows:

[binaries]
c = '/usr/bin/arm-none-eabi-gcc'
cpp = '/usr/bin/arm-none-eabi-g++'
ar = '/usr/bin/arm-none-eabi-ar'
ld = '/usr/bin/arm-none-eabi-ld'
strip = '/usr/bin/arm-none-eabi-strip'

[built-in options]
c_args = ['--specs=nosys.specs', '-mcpu=cortex-m0plus']
c_link_args = ['--specs=nosys.specs', '-mcpu=cortex-m0plus']

[host_machine]
system = 'bare-metal'
cpu_family = 'arm'
cpu = 'cortex-m0plus'  # e.g., 'cortex-m4'
endian = 'little'

When running meson build --cross-file cross_file.txt it generates correctly the a.out file for my ARM architecture. This means, the cross compiler is working correctly.

Now, when trying to cross compile the libcsp library using this same cross compiling file. I get the following error:

vladik@vladik: /Documentos/pico/testing/libcsp$ meson build --cross-file ../cross_file.txt
The Meson build system
Version: 0.61.2
Source dir: /home/vladik/Documentos/pico/testing/libcsp
Build dir: /home/vladik/Documentos/pico/testing/libcsp/build
Build type: cross build
Project name: csp
Project version: 2.0
C compiler for the host machine: /usr/bin/arm-none-eabi-gcc (gcc 10.3.1 "arm-none-eabi-gcc (15:10.3-2021.07-4) 10.3.1 20210621 (release)")
C linker for the host machine: /usr/bin/arm-none-eabi-gcc ld.bfd 2.38-3ubuntu1
C compiler for the build machine: cc (gcc 11.4.0 "cc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0")
C linker for the build machine: cc ld.bfd 2.38
Build machine cpu family: x86_64
Build machine cpu: x86_64
Host machine cpu family: arm
Host machine cpu: cortex-m0plus
Target machine cpu family: arm
Target machine cpu: cortex-m0plus
Found Pkg-config: NO
Found CMake: NO
Run-time dependency yaml-0.1 found: NO (tried pkgconfig and cmake)
Neither a subproject directory nor a yaml.wrap file was found.
Subproject  yaml is buildable: NO (disabling)
Library c found: YES

src/arch/meson.build:8:1: ERROR: _Problem encountered: invalid system bare-metal_

A full log can be found at /home/vladik/Documentos/pico/testing/libcsp/build/meson-logs/meson-log.txt

How can I modify the meson.build file inside the libcsp to avoid this error. Is CSP supported for baremetal applications? Any ideas on how to generate the libcsp.a file for CSP library for my MCU architecture?

Answer 8 · 2023-11-13T08:50:01.000Z

You are not following how we build libcsp with FreeRTOS using Meson demonstrated in https://github.com/libcsp/libcsp-freertos.

Make sure to build, say, hello world for your RPi with FreeRTOS first. Then, integrate libcsp. Unlike Linux, we do NOT explicitly build libcsp.a then link to your application. Instead, libcsp will be built as a part of the build process.

Answer 9 · 2023-11-13T10:17:29.000Z

Thanks for the update! Really appreciate it.
I think the raspberry pi pico SDK only allows compilation using CMake. It does not have support to build with Meson (and I am no expert to configure it myself).
I got the grasp on how to configure freeRTOS + libcsp for other MCUs that support compilation with Meson (quite easy, just have to call the freeRTOS-kernel for your MCU architecture and integrate libcsp).
From your previous response, I can tell that libcsp is not configured to build with freeRTOS using CMake. Will you update it in the future? Maybe all the CMake users can benefit.

Answer 10 · 2023-11-13T13:10:49.000Z

Sure. I'm happy to take changes to enable FreeRTOS integrations.

Unfortunately I do not use FreeRTOS and I have too many thing to finish before jump in to FreeRTOS world, I need help from FreeRTOS users.

As you can see from libcsp-freertos/meosn.build you need to specify which FreeRTOS kernel files you need to build. You need something like this as libcsp-freertos/CMakeLists.txt:

cmake_minimum_required(VERSION 3.20)

include(pico_sdk_import.cmake)

project(libcsp-freertos)
pico_sdk_init()

add_executable(demo
  main.c
  hooks.c
)

add_library(freertos OBJECT
  freertos/list.c
  freertos/queue.c
  freertos/tasks.c
  freertos/timers.c
  freertos/portable/GCC/ARM_CM0/port.c
)
target_include_directories(freertos PUBLIC
  ${CMAKE_CURRENT_SOURCE_DIR}
  freertos/include
  freertos/portable/GCC/ARM_CM0
)

set(CMAKE_SYSTEM_NAME "FreeRTOS")
add_subdirectory(libcsp)


target_link_libraries(demo pico_stdlib freertos)
pico_add_extra_outputs(demo)

And you need the following patch to libcsp itself. Even with this patch, it doesn't build. but I'm sure you get the idea.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 84b7213..4aa83b2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -41,6 +41,8 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
   set(CSP_POSIX 1)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Zephyr")
   set(CSP_ZEPHYR 1)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "FreeRTOS")
+  set(CSP_FREERTOS 1)
 endif()
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND
diff --git a/src/arch/freertos/CMakeLists.txt b/src/arch/freertos/CMakeLists.txt
new file mode 100644
index 0000000..cd53e17
--- /dev/null
+++ b/src/arch/freertos/CMakeLists.txt
@@ -0,0 +1,6 @@
+target_sources(csp PRIVATE
+       csp_queue.c
+       csp_semaphore.c
+       csp_system.c
+       csp_time.c
+)

Answer 11 · 2024-01-10T01:43:14.000Z

I'm closing this for now. If you have more question / commnets, please reopen it.