Fix of unknown Ringbuffer and not found USB-Serial Device

[scrapforge]

I added in prj.conf a CONFIG_RING_BUFFER=y line, due to an error while building, which stated an undefined reference occured, similar to this on zephyrproject-rtos/zephyr#30183.
Also i could not reliably reproduce the error. This line fixed any appearance of it.

Also if usb-serial configured as transport layer for microros, the code hang up. After a lot of debugging i found that in the file mymicromodule/modules/libmicroros/microros_transports/serial-usb/microros_transports.c the device is searched by its label CDC_ACM_0. Therefore an app.overlay file is needed, which i added.

I have used
zephyr 3.5.0-rc3
and
zephyr-sdk 0.16.3

[pablogs9]

I added in prj.conf a CONFIG_RING_BUFFER=y line, due to an error while building, which stated an undefined reference occured, similar to this on zephyrproject-rtos/zephyr#30183.

Could you provide details on how to trigger this build error?

Also, the CI seems to have errors

[scrapforge]

The CI for Zephyr 2.7.2 complains about:
Error: disco_l475_iot1.dts.pre.tmp:1921.1-13 Label or path zephyr_udc0 not found
FATAL ERROR: Syntax error parsing input tree.

I considered the error could be based on an api/syntax change between the versions 2.7.2 and 3.1 but as i searched the documentation for Zephyr 2.7.2 i found, that the added overlay code is the same as proposed in
https://docs.zephyrproject.org/2.7.2/reference/usb/uds_cdc_acm.html?highlight=zephyr_udc0.

So i compared the device-tree overlays disco_l475_iot1.dts for the board and got (just the important detail):

-  &usbotg_fs {
+  zephyr_udc0: &usbotg_fs {
      pinctrl-0 = <&usb_otg_fs_dm_pa11 &usb_otg_fs_dp_pa12
                 &usb_otg_fs_id_pa10>;
+     pinctrl-names = "default";
      status = "okay";
   };

So error is caused by a change in the devicetree-overlay.
Do you have a idea how to solve this?

[pablogs9]

Can you update the PR?

[scrapforge]

I'm sorry, but i dont understand you. Could you explain it?

[pablogs9]

Sure, I wonder if you can update the PR with the required changes in order to make the CI pass.

[scrapforge]

I added in prj.conf a CONFIG_RING_BUFFER=y line, due to an error while building, which stated an undefined reference occured, similar to this on zephyrproject-rtos/zephyr#30183.

Could you provide details on how to trigger this build error?

Steps to trigger this error:

• follow instructions of the latest zephyr release and install zephyr and zephyr sdk
• mkdir .../zephyrproject/applications
• cd .../zephyrproject/applications
• clone https://github.com/micro-ROS/micro_ros_zephyr_module
• west build -p always -b nucleo_h743zi micro_ros_zephyr_module

results in the error message:

.../zephyrproject/applications/micro_ros_zephyr_module/modules/libmicroros/microros_transports/serial/microros_transports.c:44: undefined reference to `ring_buf_put'
.../zephyrproject/applications/micro_ros_zephyr_module/modules/libmicroros/microros_transports/serial/microros_transports.c:102: undefined reference to `ring_buf_get'

[pablogs9]

#126 merged, could you rebase?

[scrapforge]

#126 merged, could you rebase?

I hope i did it right.

[scrapforge]

The problem that I ran (originally) into has been, that my code did compile, but when i flashed it, it didn't work. It took me while to understand, that the problem was caused by this line

device_get_binding("CDC_ACM_0");

This function call itself it not dependent on any correct hardware configuration. A string is a string.

But at runtime it tried to get the device, by a label/name not known to the zephyr OS, due to lacking configuration. So the surrounding RCCHECK of the function, which calls this code line indirect, did throw an error:

RCCHECK(rclc_support_init(&support, 0, NULL, &allocator));

So i dont think that any CI, which only compiles the code (as far as i unterstand the log), would actually detect my problem, because it only shows up at runtime.

So i can currently confirm my solution for my setup only
(Zephyr 3.5, Zephyr-Sdk 0.16, Board nucleo_h743zi)

[scrapforge]

I> Is it possible to embedded this dependency of the USB CDC transport at KConfig level. Something like the following in modules/libmicroros/KConfig

It is possible, also all warnings to the use of "select" in Kconfig apply.
The only other option i found, would to use set(<TRANSPORT_VARIABLE> 1 ) in CMake and use this to conditional add .conf files. But this couldn't be managed by Kconfig anymore, because this has to be done before Zephyr is included.

[pablogs9]

Last changes and we can merge

[pablogs9]

@mergify backport humble rolling

[mergify]

backport humble rolling

✅ Backports have been created

• #129 Fix of unknown Ringbuffer and not found USB-Serial Device (backport #125) has been created for branch humble but encountered conflicts
• #130 Fix of unknown Ringbuffer and not found USB-Serial Device (backport #125) has been created for branch rolling