I’m developing a device what can get data like CAN, GPS from autonomous drive vehicle.
When I get GPS data through /dev/ttyTHS1, The problem is happnend. ‘ttyTHS1’ is recreated constantly.
But I can get CAN data through /dev/ttyACM
Here my development environmnet.
Board: nVidia Jetson NANO OS: Ubuntu 18.04 (for Jetson NANO board from nVidia) JetPack: 4.3version Middleware: ROS melodic ROS package: ros-melodic-nmea-msgs, ros-melodic-msgs
Let’s start the first of my story.
This device can start all of programs & ros nodes automatically whenever turned on.
Because I implemented using ‘systemd & service’.
So i can see like below picture with ‘rosnode list’ as soon as I turned on this device.
There is nmea_serial_driver_node, that means the device ran ros & the node successfully.
But the node is terminated soon (in 1 minute).
Then I re-run the node with roslaunch like below.
roslaunch nmea_navsat_driver nmea_serial_driver.launch
But It’s finished by force with ‘[FATAL] permission denied error’ on the left window of the picture.
I thought this is problem related in the permission of user groups.
So I checked the group of /dev/ttyTHS1 file as you can see the terminal window of bottom right corner.
Then I added tty, dialout, and root group to my user with below command.
sudo adduser *sgr-100-nano root dialout tty
*current user name
And I could verify it like the top right in the picture.
Also, I changed the access permission of ‘/dev/ttyTHS1’.
sudo chmod 777 ttyTHS1
Then I re-run the nmea node with roslaunch.
Step 2 was half success.
I could run the nmea node without ‘[FATAL] permission denied error’ as below.
However, if I send messages, the node is finished by force again.
But, if I check the message directly with ‘cat’ command not ROS.
I can see the message sent is normally operating as below.
- I made this message on PC(windows) desktop and sent to Jetson NANO.
From above, I guess Jetson NANO can read the message thorough ttyTHS1 successfully.
On the other hand, ROS node can’t read and It is terminated by force.
So I tried to find out of the root cause. At last, I could see the ‘/dev/ttyTHS1’ is recreated constantly.
Also, from the reason, access permission of the file is changed to original. You can see this.
I don’t know why ‘/dev/ttyTHS1’ is recreated whenever It gets message.
Others are okay such as ttyACM0~2(CAN), ttyUSB0
Help me please!