Minimum update below to execute Pub/Sub demo on the mros2-mbed enviro…

[smoriemb]

Related to the issue below, I prepared a minimum update for the embeddedRTPS to run the Pub/Sub demo with Foxy environment.
mROS-base/mros2#5

It seems that cacthing up the latest one also solve the problem. But, we can confirm your mROS 2 communicating with Foxy's node without a bit large update.

[takasehideki]

@smoriemb Thanks a lot! This PR will definitely help improve quality.
However, I can't confirm the communication with Foxy (sub from mros2 node) in my environment with mros2-asp3-f767zi. Do we need any special settings?

[takasehideki]

I've confirmed this PR worked well on mros2-mbed.
It means the cause may be from TOPPERS kernel or its bindings 😢

[smoriemb]

Thanks for your confirmation.

It means the cause may be from TOPPERS kernel or its bindings

Maybe, your configuration for the amount of resource for lwip is not enough.
Actually, I managed to run the mros2 one mbed by increasing the buffer pool size of lwip as below at the first trial.

mbed_app.json
  ...(SNIPPED)...
  "lwip.pbuf-pool-size": 20    # <= the default is 5.
  ...(SNIPPED)...

And, I'm still not sure when/how we have to increase the value above.
Why don't you investigate the number of buffer pool size like above or the maximum number of the socket.

But, at least, the modification of this pull-request is required to run with Foxy no matter if the buffer size/socket number are enough or not.

[takasehideki]

@smoriemb thanks for useful information!
In mros2-asp3-f767zi and STM32CubeMX, the configuration for lwIP is referred to lwipopt.h.
However, it has been set as you mentioned,,,
https://github.com/mROS-base/mros2-asp3-f767zi/blob/main/src/startup/include/lwipopts.h#L131-L134

[smoriemb]

@takasehideki
Sorry for my later response.

Other configuration parameters might affect the result.
For example, I found the parameter below has a little less value, which I casually found in the lwipopt.h you indicated, compared to the Mbed's default (8).

TCPIP_MBOX_SIZE 6

Anyway, we might better to check if each lwip function call returns error or not, as I got over the Mbed's buffer size problem before.

[takasehideki]

Hi @smoriemb
I've been considering how to handle this PR.
The operation in ASP3 version has not been confirmed yet, but it works fine in the Mbed version. Being able to communicate with Foxy is a big step forward.

So, I decided to merge this PR. And I will create the issue for the ASP3 version and tackle it individually.

I'm sorry for the late decision. I hope that you will continue to contribute to this repository in the future.

[takasehideki]

@smoriemb I got it! The cause in ASP3 version is the size of each pbuf in the pool. We can communicate with Foxy nodes now!
mROS-base/mros2-asp3-f767zi@a069b7d