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Wireless USB

Cypress certified PSoC consultant
Cypress certified WUSB consultant
Freescale Design Alliance Partner

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SoPC Company is certified by Cypress for Wireless USB technology.

What is Wireless USB (WUSB)?

First off, itís a little bit of a misnomeró itís not just for USB, it doesnít even know about USB. Wireless USB is actually a 2.4 GHz DSS radio transceiver with a SPI interface that you can use to configure and control it and exchange data with a microcontroller. It can be used to exchange USB data, true, but it can also be used for any type of data transfer.  For example, it can be used as a wireless RS-232 interface. It has a bit-rate of up to 62.5 kbps, not fast enough for streaming video, but suitable for a very wide variety of control and data interfaces.  Itís even fast enough for half-duplex telephony.

These transceivers can handle point-to-point, multipoint-to-point (star) topologies. They are very interference immune. In fact, Cypress has demonstrated over 2,000 transceivers operating flawlessly in a confined space.

How does WUSB compare to Bluetooth, and ZigBee?

WUSB is simply a low-cost integrated circuit.  It requires three chip caps, and a chip inductor, plus a small antenna which can be etched into your PCB, along with some power supply bypassing. In fact, Cypress has an application note with all of the details on how to do that.  If you donít want to make your own radio transceiver, you can buy very inexpensive modules from Unigen.  Unlike competing technologies; Wireless USB is royalty-free, as it doesnít require a software stack, or a certain microcontroller to control the transceiver. Itís also much more user-friendly. Think of it as a piece of wire (or a segment of a data bus), that is arbitrated by a little bit of code running on your (whatever type) MCU.

Whatís the catch?  Right now WUSB doesnít handle mesh networks, weíre working on it. It is also lower-throughput than either ZigBee (about half), or Bluetooth. However, soon parts with throughput of around 250kbps will be available.

In short, WUSB is (much) lower-cost, and easier to use than other wireless technologies. Itís present somewhat lower throughput is not an issue in the majority of potential applications. Soon that wonít even be a factor.

Whatís the range?

There are chips specified for 10 meters, and others specified for 50 meters. You can add an external antenna and get very long distance reliable communication. We have heard of these being used successfully at distances in excess of one mile.

Is it secure?

WUSB is designed for security. The DSSS (Direct Sequence Spread Spectrum) transmission scheme requires both the transmitter and receiver to use the same Pseudo-Noise (PN) code. This adds a degree of security. They must be on the same channel, out of a possible 64.  And 128-bit encryption can be implemented in firmware (634 bytes of firmware in a PSoC, for example) to provide great security with a minimal impact on latency (about 1.2mSec greater latency in a PSoC than without encryption).


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