| Out in Front |
The Universal Serial Bus (USB) hands-on project remains stalled for lack of software (see “USB: a neat package with a few loose ends” pg 38). (Microsoft, Redmond, WA, released an updated beta version (OSR3) of its Windows 95 operating system in mid-September, addressing many of the timing issues that USB compatibility tests revealed. Unfortunately, the company did not provide EDN with a copy.) The USB community at large is making progress, however. Sand Microelectronics, for example, has released synthesizable USB core designs in both Verilog and VHDL formats. The designs, which include a device controller and a host controller, will also be available as fully tested programmable-logic implementations, using Lucent Technologies’ (Murray Hill, NJ) ORCA FPGA.
Other USB products are in the works, some with release scheduled by fall Comdex. Texas Instruments (Austin, TX) plans a family of devices, beginning with hub controllers. Xilinx (San Jose, CA) is developing USB reference designs for its programmable-logic families. Compaq Computer Corp (Houston), which has built USB into its Presario product line, plans to release a $199 USB color videocamera for PC-based videoconferencing.
Many of the USB IC designs now arriving sidestep the software issues that the hands-on article raises. These implementations of the bus interface use hard-wired state-machine designs rather than a microcontroller. As a result, the only programming a USB device design needs is the device-function program, which can treat the USB interface much as it would a UART, and the Windows application program. Vendors expect that the remaining software pieces of the USB communications scheme will soon be in place as off-the-shelf items.
The key piece still outstanding is the USB stack for Windows 95. That software is still in beta testing, although Microsoft expects to release a version by year’s end. Once that piece is in place, USB will be ready to become an important element in future PC-based designs. Market-research company Dataquest (San Jose, CA) anticipates that 75% of the new PCs being manufactured worldwide will carry USB by mid-1997.—Richard A Quinnell
Sand Microelectronics, Santa Clara, CA. (408) 235-8600.
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