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kevin360
Joined: 01 Jul 2009
Posts: 3
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 01 Jul 2009 21:50 Help with designing wireless switch |
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Hey everyone,
I've searched around the internet for what I'm trying to do and I'm hoping someone here can help me. What I'm trying to design is a wireless switch. Close a switch at point A and that causes a switch at point B to close - this being used as a wireless flash trigger for a camera.
Right now I'm using the Linx LR Series RF modules, along with these RF modules I'm using their LS Series encoders/decoders. This works, but I've found that these encoders create too much delay. I know it's the encoders and not the radio link because I've tested them by connecting them with a wire and I get too much delay.
So I'm wondering if anyone knows of an even simpler encoder. These are pretty simple, no addressing just four data inputs and then the serial data output.
Or, from searching on this forum I'm wondering if I could use something like a tone decoder? A tone generator connected to the TX module and then a tone decoder on the RX module to detect just that tone. Would that work? Would that be simpler? If that would, does anyone have a suggestion on a really simple/easy tone decoder/generator that I could use.
Thanks in advance for any help you can provide.
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arthur0
Joined: 28 Nov 2003
Posts: 73
Helped: 9
Location: Stockholm, Sweden
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08 Jul 2009 9:52 Re: Help with designing wireless switch |
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Hi kevin360,
The slowest sync is around 1/60s (~16ms) even in poor cameras, so in theory, a module capable of transmitting at more than 60 baud could be made to work.
The datasheet actually indicates that the debouncing mechanism in the encoder introduces about 131ms of delay, so clearly you can't use it.
But why won't control the RF chip directly? With 2 of the smallest possible uCs, you could send (and then receive) a short burst of "special" data (just to increase immunity to interference).
I would use an optical device (a modulated IR beam, for instance) instead, if you have clear line of sight between A and B, and there’s no risk of having the IR ruin you pics.
Arthur
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kevin360
Joined: 01 Jul 2009
Posts: 3
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08 Jul 2009 10:32 Re: Help with designing wireless switch |
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I already have optical/IR control for the flashes. Optical is either built into my flashes or you can get an optical slave to attach to the flashes from China for about $5. Problem with either one is when I place a flash somewhere where it doesn't see the optical or IR signal, so I'm looking at implementing an RF trigger.
I know what you are saying about the uCs but I was hoping to not having to program one if possible. I've got the tone encoder/decoder working so that when the right tone is sent the RX system turns on. I've gotta test it some more to make sure there isn't a delay with it also.
Ideally I'm trying to make a simple Pocket Wizard. Attach one to your camera, one to your flash, and you have a wireless trigger. They seem a little over priced at $170 each (need a minimum of 2, some people will use up to 6 or 8 of them) when all it is is a RF wireless switch.
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