Unable to sync with device (arduino uno)

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I came across this problem too. In my case, it was because I did not use spinOnce() function to let ROS have a chance to take control so that rosserial_arduino can make contact with arduino.

At first, I supposed I just wrote a publisher so that I did not need to use spinOnce() function at all, but it was wrong. Now I know why the official tutorial for writing a publisher) says this:

> Calling ros::spinOnce() here is not necessary for this simple program, because we are not receiving any callbacks. However, if you were to add a subscription into this application, and did not have ros::spinOnce() here, your callbacks would never get called. So, add it for good measure.

If you are sure that you are using the same version for Arduino and rosserial and still getting the same error try the instruction below.

Add line nh.getHardware->setBaud(115200); before nh.init().

This worked for me with an indigo rosserial and an Arduino Uno which uses ROS libraries generated by ros-indigo-rosserial.

Hi! I also encountered the same problem and fixed it finally. It displays "Connecting to /dev/ttyACM0 at 57600 baud" while the baud rate in my Arduino code was set to be 115200. Hence, set the baud rate as it was in your arduino code (In my case it is 115200) by adding _baud:=X (where 'X' is the baud rate between your computer and the Arduino) to the same command as follows:

rosrun rosserial_python serial_node.py _port:=/dev/ttyACM0 _baud:=115200

The other reason could be that your port is different from that of the above command. For example, check if your port to which the Arduino is connected, is as entered in the above command i.e, ttyACM0 or ttyACM1 etc . Hope this helps!

I have encountered this problem a few times and the solutions were:

1. Check baudrate is set to 115200 (as others have pointed out)

2. Check that you are advertising the topic before you attempt to publish it

   ros::Publisher my_pub("my_topic", &my_msg);
nh.advertise(my_pub); // <--- I forgot this this and it caused the described problem
my_pub.publish();

Dear Sir, I follow the link: http://wiki.ros.org/rosserial_arduino... You can install rosserial for Arduino by running: sudo apt-get install ros-indigo-rosserial-arduino sudo apt-get install ros-indigo-rosserial and then: cd /src git clone https://github.com/ros-drivers/rosser... cd catkin_make catkin_make install and when test helloworld, see the same error message: [ERROR] [WallTime: 1461904599.861522] Unable to sync with device; possible link problem or link software version mismatch such as hydro rosserial_python with groovy Arduino I follow the answer in this thread to download indigo zip file. remove the old source, rebuild the new source, and rm ros_lib and run: cd /libraries rm -rf ros_lib rosrun rosserial_arduino make_libraries.py . But I still see the same errors: [ERROR] [WallTime: 1461904599.861522] Unable to sync with device; possible link problem or link software version mismatch such as hydro rosserial_python with groovy Arduino How do we claern the old libaray. I had redo start from reinstall ros-indigo-rosserial-arduino, the result is the same.

I use arduino Yun, when I complier and upload the image, I get warning: Low memory available, stability problems may occur.

I don't know the issue is I did not clean it, or the issue is the system did not stable? Could somebody help to answer? Thank you very much! John

I've gotten this issue several times despite the fact that I am using the correct version. I found that this usually due to a connection issue and ROS not being able to connect with the Arduino. Usually the solution is to disconnect and reconnect the Arduino or to restart my computer. This usually solves the problem.