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Error serial conexion with apm mavlink


(chapulino1000 .) #1

When I throw this process in the ROV,

'roslaunch bluerov apm.launch'

I get this error
I get an overview of the connections between them and a photo.

I have something wrong connected?
The position to be used in the APM is Telem?





(Rusty) #2

Hi Chapulino,

The code is current set up to talk to the APM through USB-serial instead of raw TTL serial. If you connect a micro USB cable from the RasPi to the Arduino it should work fine! You can type ls /dev/ttyACM* at the RasPi command line to make sure that it is showing up fine!

Thanks for pointing this out. We’ll make sure this is more clear in our documentation.

-Rusty


(chapulino1000 .) #3

Great Rusty.

Now is ok.


(Jim N.) #4

Here’s another scenario: RPi2 with the Navio+ APM cape. RPi2 is debian wheezy with PREMPT_RT, kernel 3.6 something and you have APMrover2 ( all of the APM suite in fact) on board. You need to get to the APM via mavros using the current release of bluerov, but the Navio+ and RPi talk over the GPIO, not a standard /dev/… device, so there are a few things that can be done ( I think). You need the RT kernel for the RPi to run APM and chat reliably to the Navio+, data when needed, runtime garuntees and all that. So just throwing ubuntu on the pi doesn’t fit the bill. You need to get the prempt rt patch. A non-trivial task. Ok, so maybe not the best way. Another option is to use CCtronics Ros/Qt5/raspian RT image. This one is nice. CCtronics gives you a few classes to chat over the gpio to the Navio+ with little code. However, not much in the way of APM com to a ground station (top side PC in our case). However, mavros isn’t available. I couldn’t even get other ros packages installed on the system. Very frustrating. But, abandoning mavros, a new controller could be written with little effort. I’m sure with more research I’ll solve the ROS package issue, but do I want to? Another option is a fresher Ros wheezy install, which is also non-trivial and is taking me days to get right, which hopefully allows me to meet all dependencies for the current release of the bluerov package. My fingers are crossed. I’d hate to have to use pigpio and rewrite the entire stack, using mavlink etc…but maybe worth it in the end. There is also a possible fcu_url settign for APM udp://14550@ that seems like it might allow mavros to talk to the APM, but I have yet to get mavros to successfully install. Also, ROS is turning towards DDS as the underlying architecture ( which I am happy about to a point ) so an opendds impl may be suitable, but again, non-trivial to develop. other RT pub/sub architectures may fit the bill better, but we shall see. I just want a hybrid kit to explore the Chesapeake for cryin’ out loud, lol. Not that you can see much with all the crap flowing into the bay. More to come on the navio endeavor~


(Josh) #5

Hey Jim,

That sounds like an exciting project! Please create a new thread for off-topic conversations in the future.

Thanks,

Josh