Getting Started

[cruzaviles]

Hi there!

First off thank you all so much for the work here it is amazing!

I am a sophomore in college and I am trying to use this library to connect a laptop running ros2 foxy to an arduino due in order to control 5 servo motors (for a robotic arm).

I am just learning how to use ros2 and linux so a lot of this is new to me. So, I seem to have gotten lost following your first short tutorial.

I have arduino 1.8.19 installed and I followed the instructions downloading the zip from github. I then included the zip library through arduino. But, when I try to run any example code I get several "undefined reference to" errors concerning the library files.

I have tried a few things like deleting and re-installing the library, but I can't seem to find a way to resolve this and get the file to compile.

Please just let me know if I am missing something and thank you again!

[Acuadros95]

Hi @cruzaviles, Which board are you using?

[cruzaviles]

Hi @Acuadros95 thank you for your response! I am using an arduino due currently, but I do also have an ardiuno zero as a backup.

[Acuadros95]

You need to follow the steps detailed on the Patch SAM readme section.

You can also check with the arduino zero board, which should work without this patch.

[cruzaviles]

Hi there!

Since we last spoke I completed each of the steps in the Patch SAM section (I think). I know as a matter of fact that I did replace the platform.txt file, but I am still having the same error for "Undefined Reference to" and cannot use precompiled library.

Maybe I missed a step or need to do a few more things but I would love some more help.

Thank you again!

[cruzaviles]

Hi there guys!

Since last posting I have fixed a few things, and it is going better.

But, I am trying to get the publisher example working and I am having a problem. I get to the stage where I run the micro_ros_agent command and I get the output you would expect. It says that the session is established and the topic publisher and data writer are created. But, when I check the topic list I do not see the microROS publisher.

Thanks again!

[Acuadros95]

What is the output of your agent in debug mode (with -v6 flag)?

[cruzaviles]

Hi there!

Thank you for reaching out! I actually found a very helpful forum from earlier that helped me solve my issue.

I didn't end up launching from the docker like the earlier comments suggested because I am running on a due board.

But, near the end they bring up the Domain ID which was new info for me. After reading up some more I learned how to use the export command in the terminal window to change the value of the Domain ID variable. All that I did was change the value to the same number in the two terminal windows running the agent and checking the topic list. Once I did this I was able to see the topic in the list and watch it publish with the echo function.

Here is the link to the other forum that helped. https://github.com/micro-ROS/micro_ros_arduino/issues/7

[cruzaviles]

Now that I have the publisher working, I tried the subscriber example and I am pretty sure that I had it working.

So, now I would like to try and customize this code, or use it to create a new sketch, so that I can read the data from microROS to the arduino and use those value to move some servo motors.

I understand that it is probably a pretty big leap and might take some extra explaining, but I would love to learn more about how the arduino board gets data from microROS, where those values go, and then how I would be able to use those values after they are found.

If there are any helpful tutorials or links that I should follow to make this happen I would be happy to!

Thank you all again for your help!

[Acuadros95]

Glad to hear you got it working! I am closing the issue, feel free to ask more questions here or on our slack channel.

Here are some relevant links:

• micro-ROS documentation
• micro-ROS tutorials
• micro-ROS demos