WiPort / XPort

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Jared5755
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WiPort / XPort

Post by Jared5755 » Thu Sep 28, 2006 4:44 pm

Has anyone ever used the XPort or WiPort from Lantronix? There was mention of the WiPort in the last issue of Servo. I have a WiPort development board and I was thinking about trying to stream video over the internet with it. Do you think it's possible?

I assume I would need some sort of interface circuitry to connect the camera to the WiPort.

Any ideas?

Jared

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philba
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Post by philba » Thu Sep 28, 2006 9:18 pm

check the interface speed of the wiport. I've used the xport. the interface is async serial and, iirc, it's upper bound is something like 230K baud. I believe the wiport is similar.

A qcif camera will have 76.8K pixels per frame multiplied by the frame rate. At 7.5 fps, we are talking 576K pixels per second. multiply that times the pixel depth and you can see that you are going to have to do some pretty significant compression to get that down to 230K bits per second. That's going to take more than a lowly little microcontroller on 2 counts - performance and memory. I don't know if an ARM could do it, maybe one of the lower end x86 embedded boards. at this point you are better off running linux, using a cheap wifi card.

stevech
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Post by stevech » Thu Sep 28, 2006 11:00 pm

network cameras with WiFi built in are down below $100 (for a cheap-o CMOS cam)

I have a WiPort. You can write your own code and have it run inside the WiPort's OS. But the WiPort's integral I2C bus isn't wired to the WiPort's pins.

see also www.wibotics.com

Jared5755
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Post by Jared5755 » Fri Sep 29, 2006 6:16 am

What do you think of this camera? It says it has a serial interface and is 460800 baud. I could stream that over the WiPort pretty easily couldn't I?

http://store.wibots.com/sevicaco64.html

Newz2000
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Post by Newz2000 » Fri Sep 29, 2006 7:02 am

Jared5755 wrote:What do you think of this camera? It says it has a serial interface and is 460800 baud. I could stream that over the WiPort pretty easily couldn't I?
That's a cool camera, but you'll need to make sure you can transfer at least 460800 baud, and really, unless they're saying "a 460800 baud connection is exactly what you need" (they're probably instead saying the stream is about 460,800 b/s) you'll want to add a little for the serial protocol. I usually add 2b for every B in my math, and I'd actually be more precise if I were spending the money on a wiport.

You won't be able to compress that datastream. Its not text, it's jpeg frames, which are already compressed. The only way you'll get that smaller is by decoding the stream, recompressing the jpegs so that they lose quality, then re-encoding the stream. This process would probably overwhelm even a low-end pentium based computer.

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philba
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Post by philba » Fri Sep 29, 2006 9:36 am

yes, you have to factor in the stop and start bits though when you see baud quoted, it usually includes those bits.

the wiport does claim to have a 460800 baudrate so maybe you can just hook them together. I have no idea if stop/start/parity will match.

Jared5755
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Post by Jared5755 » Fri Sep 29, 2006 10:54 am

Thanks a lot guys for the help. I'm not sure what I'll do yet, but now I have a better idea.

Jared

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