Linux - FreeRTOS communication using callbacks

[anakorenko]

Hello, I'm trying to implement the next erpc client-server communication. My erpc server is running under Cortex-M4 microprocessor under FreeRTOS and CMSIS_UART as communication interface.
My client is running under Linux. Client-server communication is working fine, but I got some difficulties in setting server callback back to client.
In all discussions I've found all server to client callbacks are working when both client and server using the same architecture: e.g server and client are both under Linux and using pthreads, or server and client are using FreeRTOS threads.
Is it possible to implement server callbacks to client when they are running on different archs?

[github-actions]

Hi eRPC user. Thank you for your interest and welcome. We hope you will enjoy this framework well.

[Hadatko]

Hi @anakorenko , different architecture shouldn't be an issue. But currently it is supported in C only. The way how it works is that erpc is sending index to an array of functions which is created on both sides by erpc.

[anakorenko]

Thank you, @Hadatko, for quick replay. If architecture isn`t an issue how to configure threading in erpc_config.h? Can I setup client for pthread and server for freertos multithreading?

[Hadatko]

Hi @anakorenko , as you will have two applications, each application will have its own erpc_config.h file where you can specify different enviroment settings.

[anakorenko]

Thank you, your answer helped me. But i have another questions do i need to use arbitrator in this case?

[Hadatko]

You are welcome. Arbitrator need be used if you have client and server on each side. So you want do client requests from both sides and servers will respond on both sides.

[anakorenko]

Greate, thanks, now i`m trying to make my callbacks work using examples from test directory, but somehow receiving strange error when trying to compile server-side of the application:

/usr/local/gcc-arm-none-eabi-10.3-2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/bin/ld: _build/nrf52840_xxaa/erpc_demo_server.cpp.o: in function `linuxTonordic_service::myFun_shim(erpc::Codec*, erpc::MessageBufferFactory*, unsigned long)':
/home/artem/Documents/Packetcraft/ProjFreeRtos/pca10056/blank/armgcc/../../../erpc_demo_server.cpp:76: undefined reference to `erpc_malloc'
/usr/local/gcc-arm-none-eabi-10.3-2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/bin/ld: /home/artem/Documents/Packetcraft/ProjFreeRtos/pca10056/blank/armgcc/../../../erpc_demo_server.cpp:111: undefined reference to `erpc_free'
/usr/local/gcc-arm-none-eabi-10.3-2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/bin/ld: /home/artem/Documents/Packetcraft/ProjFreeRtos/pca10056/blank/armgcc/../../../erpc_demo_server.cpp:111: undefined reference to `erpc_free'
/usr/local/gcc-arm-none-eabi-10.3-2021.10/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/bin/ld: /home/artem/Documents/Packetcraft/ProjFreeRtos/pca10056/blank/armgcc/../../../erpc_demo_server.cpp:111: undefined reference to `erpc_free'

This errors occurs only if i use out in my function arguments
myFun(in callback1_t pCallback1_in, out callback1_t pCallback1_out) -> void

And second question. I need to execute some code on a client side using parameter from server side. For example i have this function on my client:
void testfun(bool onOff){ if(onOff) printf("true\n"); else printf("false\n"); }
i want to pass it to my server using callbacks

myFun(callback, &pCallback1_out);

on server side set argument as true and execute it back on client. Is this gonna work? Many thanks)

[Hadatko]

You need choose erpc_port_*.cpp file from https://github.com/EmbeddedRPC/erpc/tree/develop/erpc_c/port

[anakorenko]

Yep, now it works, and what about second question?

[Hadatko]

Sorry i missed your question. No, you need also pass onOff as out parameter for function (same call or new call)
e.g:
myFun(callback, &pCallback1_out, &onOff);
of
myFun2(out onOFF)

[anakorenko]

Hello again, can i use arbitrator on linux-rtos communication setup? I have seen couple of examples and in every FreeRTOS is used to run client and server tasks simultaneously. But in my case i can`t use FreeRTOS on the second end of setup. Also i saw issue #101, and option where callback is executed on a client is exactly what i want to create. Thanks

[Second222None]

Hi, I am also doing a similar thing. The difference is that the communication middleware is USB_CDC.
I focus on the server-side application now. And FreeRTOS runs on STM32.
According to the Porting Guide, I choose the erpc_port_freertos.* and change the erpc_config.h. Here is the episode from my CMakeList.txt:

file(GLOB_RECURSE SOURCES "startup/*.*" "Middlewares/*.*" "Drivers/*.*" "USB_DEVICE/*.*" "Core/*.*" 
"Communication/*.*"
"autogen/*.*" 
"erpc/erpc_c/config/*.*"
"erpc/erpc_c/setup/erpc_setup_usb_cdc.*"
"erpc/erpc_c/setup/erpc_server_setup.*"
"erpc/erpc_c/setup/erpc_client_setup.*"
"erpc/erpc_c/transport/erpc_usb_cdc_transport.*"
"erpc/erpc_c/transport/erpc_serial_transport.*"
"erpc/erpc_c/port/erpc_serial.*"
"erpc/erpc_c/port/erpc_port_freertos.cpp"
"erpc/erpc_c/port/erpc_setup_extensions_freertos.cpp"
"erpc/erpc_c/port/erpc_threading_freertos.cpp"
)

I received a compiling error:

In file included from /home/birdman/FOC/erpc/erpc_c/setup/erpc_setup_usb_cdc.cpp:12:
/home/birdman/FOC/erpc/erpc_c/transports/erpc_usb_cdc_transport.hpp:21:10: fatal error: fsl_component_serial_manager.h: No such file or directory
   21 | #include "fsl_component_serial_manager.h"
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [CMakeFiles/FOC.elf.dir/build.make:843: CMakeFiles/FOC.elf.dir/erpc/erpc_c/setup/erpc_setup_usb_cdc.cpp.obj] Error 1
make[2]: *** Waiting for unfinished jobs....
In file included from /home/birdman/FOC/erpc/erpc_c/port/erpc_serial.h:50,
                 from /home/birdman/FOC/erpc/erpc_c/port/erpc_serial.cpp:39:
/usr/include/newlib/termios.h:4:10: fatal error: sys/termios.h: No such file or directory
    4 | #include <sys/termios.h>
      |          ^~~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [CMakeFiles/FOC.elf.dir/build.make:778: CMakeFiles/FOC.elf.dir/erpc/erpc_c/port/erpc_serial.cpp.obj] Error 1
make[1]: *** [CMakeFiles/Makefile2:76: CMakeFiles/FOC.elf.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

What am I missing? Does modification of erpc_erpc_usb_cdc_transport.* required?
I am new to this. Can anyone help?
Thank you.