ROS2 Ultrasonic Range Package

[camp .]

Hey folks!
Big times at the ROS Discussion Group this evening! Starting with a functioning Raspberry Pi/Python ultrasonic script: https://tutorials-raspberrypi.com/raspberry-pi-ultrasonic-sensor-hc-sr04/
 

And a functioning publisher and subscriber package as described in the ROS2 tutorial: https://docs.ros.org/en/foxy/Tutorials/Writing-A-Simple-Py-Publisher-And-Subscriber.html

 

And with Big Time Help from Ralph Gnauck and Michael Wimble. We have converged the packages and made a "ROS2 Ultrasonic Range Package."
 
Below find attached the modified ultrasonic Python package and the modified simple publisher. First, create the "simple publisher" per instructions and then replace "publisher_member_function.py" with the modified version and place the modified "ultrasonic_distance.py" in the same directory. Compile and run "ros2 run py_pubsub talker" to start the publisher and "ros2 topic echo /distance" to see the distance being published as a range topic. The next step is to create a range subscriber. Again Big Thanks to Ralph and Mike. Big Thanks!
 
- Camp

[camp .]

    Almost a year ago at the ROS Discussion Group, we folded a "Raspberry Pi/Python ultrasonic script" into the ROS2 Tutorial "Python Simple Publisher" and made a ROS2 ultrasonic publisher. I'm trying to duplicate this but am getting the below error message when launching "ros2 run py_pubsub talker."

 

-------------------------------------------------- snip --------------------------------------------------

Traceback (most recent call last):
  File "/home/camp/dev_ws/install/py_pubsub/lib/py_pubsub/talker", line 33, in <module>
    sys.exit(load_entry_point('py-pubsub==0.0.0', 'console_scripts', 'talker')())
  File "/home/camp/dev_ws/install/py_pubsub/lib/py_pubsub/talker", line 25, in importlib_load_entry_point
    return next(matches).load()
  File "/usr/lib/python3.10/importlib/metadata/__init__.py", line 171, in load
    module = import_module(match.group('module'))
  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/home/camp/dev_ws/install/py_pubsub/lib/python3.10/site-packages/py_pubsub/publisher_member_function.py", line 18, in <module>
    import py_pubsub.ultrasonic_distance as p
  File "/home/camp/dev_ws/install/py_pubsub/lib/python3.10/site-packages/py_pubsub/ultrasonic_distance.py", line 13, in <module>
    GPIO.setup(GPIO_TRIGGER, GPIO.OUT)
RuntimeError: No access to /dev/mem.  Try running as root!
[ros2run]: Process exited with failure 1

-------------------------------------------------- snip --------------------------------------------------

 

    I've got two systems. One is Ubuntu 20.04 and foxy which works and the other is Ubuntu 22.04 and humble where I'm getting the above error. I am checking all the files including "publisher_member_function.py" and "ultrasonic_distance.py" which are identical plus package.xml, setup.py and setup.cfg.

    I also get an error with colcon build that I do not get with the original installation.

 

-------------------------------------------------- snip --------------------------------------------------

Starting >>> py_pubsub

--- stderr: py_pubsub                   
/usr/lib/python3/dist-packages/setuptools/command/install.py:34: SetuptoolsDeprecationWarning: setup.py install is deprecated. Use build and pip and other standards-based tools.
  warnings.warn(
---
Finished <<< py_pubsub [3.87s]

Summary: 1 package finished [4.67s]

  1 package had stderr output: py_pubsub

-------------------------------------------------- snip --------------------------------------------------

 

Suggestions?

 

Thanks,

Camp

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[camp .]

    I figured out what it was. I needed to install "rpi.gpio-common" and add myself to the dialout group.

 

Thanks!

Camp

To view this discussion on the web visit https://groups.google.com/d/msgid/hbrobotics/1764092052.3411824.1660788587163%40mail.yahoo.com.