TCP Socket bare-metal, can it be done?

AndrewST · ‎2025-04-05

Hi,

I am running a simple TCP server using the lwIP stack and no RTOS. I got help from the "Echo_Server" example offered in most ST eval board packages, everything works fine.

I need to accept a single socket connection from the outside and maybe also establish one as a client.

I understand that because sockets are sort of blocking, they are often implemented in a multi-thread environment. I am trying to not use any OS. Any type of the F series microC will do.

Has anyone ever implemeted lwIP sockets without any OS? Can it be done?

Thank you.

AndrewST · ‎2025-04-05

We know the API as it is requires those mechanisms and therefore some sort of OS. That has been stated a thousand times already in this thread. The question is: has someone done it without an OS (cherry on top would be to know how).

Danish1 · ‎2025-04-05

With blocking code, everything that needs to be done to unblock must happen “by magic” - in other threads or by interrupt service routines. And things like semaphores, thrrad-safe queues are all helpful.

An OS will provide calls for those.

Or you could write them from scratch.

I use the “Crossworks Tasking library” that comes with the (paid-for) Rowley Crossworks IDE to give me multiple threads, semaphores etc. I don’t regard it as an Operating System. Does that count as an OS or not by your criteria?

A lot of my decisions are historic - the project started pre-stm32cube. And I like the Rowley Crossworks IDE.

I use the netconn api of LWIP. Do you specifically want their Socket API?

I suppose I should add that my system can accept incoming TCP connections.

So whether or not I have succeeded depends on your specific interpretation of terms like socket an OS

AndrewST · ‎2025-04-07

Interesting.. Thanks for sharing.

@Danish1 wrote:
I use the “Crossworks Tasking library” that comes with the (paid-for) Rowley Crossworks IDE to give me multiple threads, semaphores etc. I don’t regard it as an Operating System. Does that count as an OS or not by your criteria?

The owners themselves call it an RTOS, so I guess it does count as an OS. From Rowley's website: "CTL is a real-time operating system designed for deployment in embedded systems that require a solid foundation to support their application infrastructure.".

@Danish1 wrote:
So whether or not I have succeeded depends on your specific interpretation of terms like socket an OS

Forgive me but there isn't any "interpretation of terms" on my end. A TCP socket is a TCP socket. lwIP's Netconn is a broader TCP API and their Socket API relies on it, sure, but it is not socket.

Your work was definitely in the same realm as the question I asked, but it was not baremetal and it was not socket.