Mikeytoo
Posts: 2
Joined: Mon Mar 02, 2015 3:01 pm

WiFi connecting two RBP's w/o router

Mon Mar 02, 2015 3:38 pm

During the summer months we race modified riding lawn mowers on a 200ft drag strip that is set up on a city street. We have the timers, light traps, Christmas tree etc to make our events look like a real NHRA event. Our problem is that everything at the finish line is connected with cables that run 200+ feet down the middle of the track. They take a long time to run and are susceptible to damage if a mower crosses the middle of the track. The fastest mower running last year went 200 ft in 3.9 sec @ 71.5 mph, lots of fun until you fall off.
I need to run the finish line timing light, speed timing light, win light low voltage relay signal analog signals into a RBP and wirelessly transmit 200 feet to another RBP to convert back to analog. Tha manufacturer of the timing system will not help us, I've had to scope all the signals to determine what is going on.
Is this possible, if so can somebody point me the right direction? Power for the RBP will be provided by a car battery supplying an inverter, we have plenty of AC and old PC power supplies for DC.

Thank you in advance for your help
Mike

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: WiFi connecting two RBP's w/o router

Mon Mar 02, 2015 3:57 pm

So your basic problem is that you want to wirelessly connect to Pis to each other over a distance of about 200 feet out in the open, and you want to do it without a access point somewhere in the middle.

Yes, that is completely possible. You'll want to read up on configuring an "ad-hoc" wifi connection in Linux.

To cover that distance you'll probably need to boost the wifi signal on each pi... something like this might be enough to cover the distance
Dear forum: Play nice ;-)

Mikeytoo
Posts: 2
Joined: Mon Mar 02, 2015 3:01 pm

Re: WiFi connecting two RBP's w/o router

Mon Mar 02, 2015 4:14 pm

I'll start looking into Ad-hoc connections today. I've used Pringles potato chip cans in the past to increase range, are the smaller corn cans better or just easier to point?
Thank you for the help!

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: WiFi connecting two RBP's w/o router

Mon Mar 02, 2015 4:38 pm

I had just picked a random one off the internet as way of an example :)
Dear forum: Play nice ;-)

User avatar
DougieLawson
Posts: 39569
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: WiFi connecting two RBP's w/o router

Mon Mar 02, 2015 4:43 pm

abishur wrote: Yes, that is completely possible. You'll want to read up on configuring an "ad-hoc" wifi connection in Linux.
Except that there isn't a WiFi dongle that I've found that supports ad-hoc. You'd need to set one up as an access point with hostapd and the other as a regular infrastructure client.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All fake doctors are on my foes list.

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: WiFi connecting two RBP's w/o router

Mon Mar 02, 2015 4:56 pm

DougieLawson wrote:
abishur wrote: Yes, that is completely possible. You'll want to read up on configuring an "ad-hoc" wifi connection in Linux.
Except that there isn't a WiFi dongle that I've found that supports ad-hoc. You'd need to set one up as an access point with hostapd and the other as a regular infrastructure client.
I stand corrected, thanks Dougie!
Dear forum: Play nice ;-)

User avatar
DougieLawson
Posts: 39569
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: WiFi connecting two RBP's w/o router

Mon Mar 02, 2015 5:01 pm

abishur wrote:
DougieLawson wrote:
abishur wrote: Yes, that is completely possible. You'll want to read up on configuring an "ad-hoc" wifi connection in Linux.
Except that there isn't a WiFi dongle that I've found that supports ad-hoc. You'd need to set one up as an access point with hostapd and the other as a regular infrastructure client.
I stand corrected, thanks Dougie!
Doing that with hostapd is a common thing and very well documented. Use a RT5370 based dongle because they are easier to get running.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All fake doctors are on my foes list.

Return to “General discussion”