Getting the KIPR LINKS to communicate with each other

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Danielle_4541
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Hi, my name is Danielle. I was at GCER 2013 and was wondering on how you could make the KIPR LINK communicate with each other either wireless or with cords that you know of. If not will I have to "hack" into the LINK to have it communicate with another LINK? Also, if there is a way to have the LINKs communicate with each other would t be through WiFi, Infrared, or another type of communication? If anyone knows any information on how to get the LINKS to communicate, it would be appreciated.

-Danielle Garcia
SODA Robotics '14
daniellegarcia4541@gmail.com

Jeremy Rand
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Hi Danielle,

Supposedly the Links have an IR transceiver, but I don't believe it is exposed in the current version of libkovan, so you can't access it right now. I believe KIPR plans to fix this by next season.

The Links have built-in WiFi, and you can use this to exchange information. If you want to try this out, look up the "ssh" Linux command, and use it via the system() C function on one Link to execute the "touch" command on the other Link. This will create a file on the 2nd Link's filesystem (I recommend creating the file in the /tmp/ folder). You can then use the access() C function on the 2nd Link to check whether the file has been created yet. My team did this in KIPR Open in 2012; it worked reasonably well.

If you want more advanced communication, you can look up how to do TCP sockets on Linux; it's harder than ssh+touch but allows transferring large amounts of data more efficiently.

Be aware that WiFi is banned in Botball tournament play due to the potential for semi-autonomous cheating, so this is only useful in non-Botball situations (KIPR Open and KIPR Aerial do allow WiFi). The IR transceiver is (I think) legal in Botball.

Cables may be possible, but I haven't tried. If you have any luck with it, please let us know.

Hope this helps.

EDIT: If you want to exchange more data than just a blank file but don't want to use sockets, look up the "scp" Linux command.

-Jeremy Rand
Senior Programmer, Team SNARC (2012-2013), Norman Advanced (2010-2011), Norman HS (2008-2009), Norman North (2005-2007), Whittier MS (2003-2004)
2012-2013 VP of Tech, 2011 President, Botball YAC (2009-2013)
Mentor, Alcott and Whittier MS

Beta
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Jeremy is correct about IR not being implemented this season. We are hoping to get that done next season.

If you're looking to get two Links to communicate over Wi-Fi, the correct approach is to use TCP sockets. Sockets are an operating system primitive that allows your program to connect to other programs on the same machine, other local machines, and other machines around the world. TCP is one layer on top of sockets that handles most of the nuances for you. (This is what HTTP, the internet's protocol, is built on by the way).

In any case, using sockets in C is not for the faint of heart. It's an extremely useful thing to understand, though, so sitting down and learning it would be beneficial for your understanding of networking and of programming in general. I would recommend Beej's Guide to Network Programming. Once you have your networking code functioning on a computer, moving it over to the Link should be trivial.

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yandrewalter
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Hi, is your concern about KIPR LINK already fix? I have this issue too, but no way to get it resolve after the update. Share some story please.

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ted90
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newstart027
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