Cannot initialize/control PWM when running ROS node (permission denied)

[djsuo (James Suo)]

I was able to run the servor.py or motor.py (written by modifying servo.py) under the folder Navio2/Python by “sudo python motor.py”, this works fine and my wheel can rotate and move.

The problem is that I need to incorporate these two functions to the ROS node and got an IOError because permission denied: ‘sys/class/pwm/pwmchip0/export’ when I ran “rosrun my_package_name node_name.py”

I then type “chmod 666 /syss/class/pwm” and used “rosrun my_package_name node_name.py” to run my node again, but got another OSError of rcio (see graph attached).

It seems I always got errors when trying to control pmw pins by running ros node using rosrun.

Any suggestions? (Note: I cannot use “sudo rosrun” to get the persmission as I did for the example in the very beginning…)

[kirill.kobylyanskiy]

Hi, @djsuo
You can’t use sudo as your environment variables aren’t set for user root, therefore it’s impossible to run rosrun. You can login as root and source setup.bash. Then everything should work.