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EXPO MUSINGS

by Tom Cantrell

Start • Bye-Bye VME, Hello PC • Build a Better Box • Wire Fires • I Want My PCTV • Sources 

WIRE FIRES

It’s been a long time coming, but USB is finally real (ironically, in no small part, thanks to Apple). Intel put it on the motherboard years ago so it was only a matter of time (and, finally, some driver support in Win98) before the inexorable march of installed base would prove compelling.

Finally, there’s a good selection of USB gadgets down at the local Computer Shop and equally important, the price is getting competitive. It’s even likely the stuff will work without too much fuss and bother—you know, after you get a driver disk or two.

Thanks to the long gestation, there’s no shortage of USB silicon. The engineer designing a high-volume product can look forward to free lunches from a raft of would-be chip, ASIC, and IP providers.

But true success for USB also depends on support for off-the-wall, special-purpose add-ons. These applications require performance and versatility beyond that of some teensy mouse chip, and designers are willing to pay for it. If that’s where you’re at, consider the NET2890 from NetChip (see Figure 2).

(Click here for figure)

Figure 2—The NET2890 from NetChip is a USB peripheral that hooks to any processor, just like a UART or Ethernet chip. With a high-speed, processor-independent bus, DMA, built-in FIFOs, and packet management that includes automatic retries, the ’2890 offers an easy way to retrofit USB to existing designs.

Performance and flexibility will remain USB watchwords if the buzz about a new USB 2.0 pans out. I must say, I’m not sure about the reasoning behind a USB that runs at 240 Mbps given its roots as a measly 1.2-Mbps mouse/keyboard link. Feature creep, indeed!

Maybe it has something to do with the growing momentum behind IEEE 1394 and the fact that non-Wintel forces, including Apple and consumer A/V giants like Sony and Philips, seem to be in the driver’s seat?

Which standard high-speed serial link should designers count on? If in doubt, consider Device Bay, a rack-and-stack packaging scheme promoted by Compaq and others that uses a connector incorporating both IEEE 1394 and USB (see Figure 3). 

(Click here for figure)

Figure 3—Device Bay takes a middle-of-the-road approach to the war over standard high-speed serial links. This rack-and-stack packaging scheme (promoted by Compaq), offers a connector that incorporates both IEEE 1394 and USB.

Although the main focus is on the desktop, there’s no theoretical reason why Device Bay can’t support all manner of embedded add-ons, which is exactly the approach taken by Granite Microsystems (see Photo 7).

Photo 7—Granite Microsystems offers a design-porting service to move existing ISA and PCI add-on card designs, such as the four-port serial card shown here, to Device Bay.

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