Small WLAN circuit

[janne102]

I need to fit a WLAN transmitter into a tube, with inner diameter of 27mm or just over one inch, to transmit a lot of sensor data to a stand-by computer. The performance does not necessarily need to be stellar, 10Mbit or higher, and I can build my own circuit board to connect a set of chips. However, it would be nice to use something that is as close to a complete product as possible like a complete multi-chip module and I would prefere not to have to deal with implementation of specific protocols. I haven't been able to find hardware that small, so far, but maybe someone can help me out here?

 

[VEBill]

The 'USB stick' form factor would probably fit into that tube - I believe that there are Wi-Fi or Bluetooth sticks (?). You would need to interface to the USB port, probably a single-chip controller. It might end up being about 6 inches long by the time you're done.

 

[VEBill]

I just did a very quick search and the USB Wi-Fi sticks are readily available. The one I looked at was 27mm by 9.5mm by some length, which (unfortunately) makes the diameter required (the diagonal) just slightly more than 27mm. You'll have to find a small one, or file down the corners of the stick's housing...

 

[Yashu]

http://www.lantronix.com/device-networking/embedded-device-servers/wiport.html

http://www.mouser.com/catalog/620/90.pdf

However, might be a tight squeeze..

 

[janne102]

Thanks a lot for the advice. I will check if I can squeeze the Lantronix box in or if the USB adapters will work for us. This gets me going.

 

[Yashu]

Not sure implementing a USB host to talk to the USB adapter will be that trivial.

Here's some CF solutions you might find interesting:

http://www.iosoft.co.uk/

http://www.edtp.com/

 

[Yashu]

Part 2

The new SanDisk WiFi SDIO card would probably be easier to do a driver for than the USB adapter.

http://www.sandisk.com/retail/c-wifi-sd.asp

but, I've been searching for embedded WiFi stuff for years and the driver is always the problem when you have no OS.

Consider using BlueTooth... lots of stuff starting to show up recently:

http://www.blueradios.com

http://www.a7eng.com

 

[Skysoldier]

check out Aerocomm.com
They have a complete wireless module that is 1 inch square.
Part # is AC4490-1x1. It is plug and play.

 

[janne102]

Thank you everyone. Your suggetions collect to a nice wireless library. Unfortunately, no cigar yet because either the protocol is way cumbersome to implement (USB stuff) or the speed is too low (Lantronix, Aerocomm, BlueTooth). I guess my application is too difficult for commercially available technology right now...

 

[VEBill]

Perhaps we should ask more about your sensor data.

Is it possible to just sent the raw sensor data (analog) using a good old fashioned, analog input, RF transmitter?

 

[janne102]

Good idea but I have already built a complicated sensor system with 24-bit AD outputs from 10 channels. The sampel rate is almost 3kHz, so there is a ton of information. I start out by storing it on a SD memory card. Then I transmit this to my laptop but my current BlueTooth connection is sooo slow and a true bottleneck that limits how much data I dare to collect.

 

[VEBill]

Back to USB sticks for a moment...

Link:

http://www.microchip.com/usb

Single chip controllers with embedded USB.

Still, far from trivial.

 

[Yashu]

My embedded 802.11b WiFi design can transmit a 1500 byte packets in 5 milliseconds worst case.

This is even using TCP with [PSH] and [ACK].

If you go UDP, you can easily double it.