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Why do we need the time sync functions? arduino node handle

asked 2019-02-28 07:52:19 -0600

gab27 gravatar image

updated 2019-02-28 12:58:57 -0600

Hi

Why do we need the time sync functions in the node_handle.h file? link text Whats the problem if the clock from the arduino and the host are not in sync? The arduino starts from 0 and from 1970 or something.

And if I use node_handle.now(), is this the time from the host or the Arduino?

Thanks

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answered 2019-02-28 10:09:38 -0600

ahendrix gravatar image

Time sync between the host and the Arduino is needed so that data captured on the Arduino can be accurately timestamped.

node_handle.now() returns the time synchronized from the host.

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ok thanks But why not only take the time from the host? I do not get why they have to be synchronized? If I timestamp an event on the Arduino with the host time (48 years or something) is this a problem? If there is a second(later) event then I timestamp it with 48 years plus a few milliseconds? Thx

gab27 gravatar imagegab27 ( 2019-02-28 11:16:04 -0600 )edit

The ROS messages are created and serialized on the arduino; the rosserial_python node that runs on the host doesn't have any knowledge of the internal message structure.

ahendrix gravatar imageahendrix ( 2019-02-28 11:30:15 -0600 )edit

This allows you to write only the software that runs on the arduino, and to use a generic ROS node to connect the arduino to the rest of ROS.

ahendrix gravatar imageahendrix ( 2019-02-28 11:30:22 -0600 )edit

Anyway, I'm happy to explain (as best I can) the reasons and uses for rosserial, but I'm not here to argue about it.

ahendrix gravatar imageahendrix ( 2019-02-28 11:32:34 -0600 )edit

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Asked: 2019-02-28 07:52:19 -0600

Seen: 169 times

Last updated: Feb 28