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2015-04-22 15:40:31 -0500 commented answer raspberry pi with ROS Indigo ( or any new Release of ROS)

Fine, this will simplify the life a lot :)

2015-04-19 17:48:38 -0500 commented answer raspberry pi with ROS Indigo ( or any new Release of ROS)

It should be a better option anyway, since ROS was a bit sluggish on the RasPi. Having several core can help. Not yet tested.

2015-04-19 15:22:05 -0500 commented answer raspberry pi with ROS Indigo ( or any new Release of ROS)

@MattHoward Sorry it couldn't help you more :/ Which error do you encounter exactly ? The same dependency as I got, or something else ?

2015-04-18 04:32:02 -0500 commented answer raspberry pi with ROS Indigo ( or any new Release of ROS)

@MattHoward I successfully managed to finalize the process, and get a working environment. It's documented (with all console traces) here : http://www.pobot.org/ROS-sur-Raspberr... Sorry for this, it's written in French. But Google Translate can help, and traces are in English ;)

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2015-01-13 01:18:24 -0500 commented answer Best choice for controlling GPIOs (published messages or service calls)

Thanks Dan for you quick reply. You confirm what I had concluded from studying existing material. The very last point was also something I had in mind. Regards.

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2015-01-12 15:19:52 -0500 asked a question Best choice for controlling GPIOs (published messages or service calls)

Hello,

Sorry if this is an already answered question, but despite a couple of hours spent googling the Web and searching in this forum, I couldn't find.

What is the rule of thumb for deciding if some control operation should be implemented using published messages or service calls ?

For controlling robot moves, I could see that the standard way is to use Twist messages published on the /cmd_vel topic. But what about controlling GPIOs for instance ? Should this be using published messages too or service calls ?

Since there is no feedback when using messages (you can't know if somebody heard them and process them), I would be tempted to use service calls instead.

Thanks in advance for any advice. Best regards. Eric

2015-01-12 14:55:37 -0500 commented answer How to write a motor controller driver?

Hello, I was just about doing the same thing. Do you plan to publish your work ? Using Twist messages sounds fine for a differential robot powered by the RoboClaw, but what about using it as a 2 independent motors controller ? Twist messages don't make that much sense here. What would you use ?

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2014-12-22 04:16:38 -0500 answered a question Announce ROS master by zeroconf

Hello,

If your target is Linux based, you can use avahi-daemon on it to advertise it on the network as <hostname>.local by default (this can be modified by configuring the daemon). On the client side, you can then identify the target by its host name.

If you need the IP, the command avahi-browse -artp | grep <hostname>.local will output records providing details about the Avahi services published by the target, including one containing the IP. It is pretty easy to select and parse it thanks to cut and alike.

An alternative to the grep approach is to publish a service on the target side using avahi-publish. On the client side you can then use avahi-browse -t <servicename> -p which will limit the output records to the relevant ones.

This solution is independent from ROS and can be exploited in startup scripts, both on target an client sides. I've used it with success in a lot of various situations involving headless Linux based black boxes, including Raspberry ones.

Hope this helps

Regards, Eric

2014-11-03 15:29:39 -0500 commented answer raspberry pi with ROS Indigo ( or any new Release of ROS)

@awilson I couldn't find any doc on the meaning of the :any suffix BTW. Maybe the procedure described in this article should mention to install these packages using pip and not letting rosdep trying to do the job. Or am I misunderstanding something ?

2014-11-03 02:30:38 -0500 commented answer raspberry pi with ROS Indigo ( or any new Release of ROS)

@awilson Thanks a lot for your quick reply. I could bypass the problem by removing the "python:any" dependencies in /var/lib/dpkg/status and the whole process went fine. I'm installing the basic ros_comm variant. Could it be some change in the ubuntu repo the "python:any" depends clause points to?

2014-11-02 15:51:53 -0500 commented answer raspberry pi with ROS Indigo ( or any new Release of ROS)

I followed it, and it works fine until step 2.2.2 (rosdep install). It fails installing python-catkin-pkg and thus dependants, saying : "python-catkin-pkg : Depends: python:any (>= 2.7.1-0ubuntu2) but it is not installable" Of course Python is here (2.6, 2.7.3 and 3). Thanks in advance for any clue.