by Lindsey Vereen
Although I’m sure everyone has heard quite enough about Moore’s law, like the manatee in
the bathtub, it can’t really be ignored. Engineers have more logic gates to work with than they ever dreamed possible, leading to the realization of the vaunted system on a chip. But engineers can only implement so many gates per unit of time, which makes it difficult to exploit all of that real estate. The functions that companies want to implement are complex, and the idea of buying it rather than hiring experts to design it has significant appeal.
The need to buy rather than build has given rise
to the hardware intellectual property business. In recent years, the term intellectual property, or IP, has been co-opted by the hardware folks and has come to refer almost entirely to hardware that can be implemented in silicon, such as processor and peripheral cores, PCI interfaces, and such. Several design groups that have come up with a useful bit of design magic like an IEEE-1394 core have been able to use it as a springboard to start their own companies.
IP isn’t the answer to all of your
design problems. The drawbacks to using IP are manifold. Standards haven’t been established to assure a smooth integration. Test methodologies may differ for the different cores. Debugging software on single-chip systems is of course a challenge. And the high non-recurring engineering cost associated with semicustom devices precludes all but the most well-heeled players from taking this route, and then only for high-volume products.
Another implication of Moore’s law is that processor speeds are
increasing dramatically. The same forces that allow increased amount of usable real estate on a piece of silicon also make possible fast yet inexpensive microcontrollers. Historically, a reason for implementing an algorithm in hardware rather than in software was execution speed. Faster processors allow you to perform more functions in software now than ever before.
Here are just two examples. Scenix Semiconductor, a company that offers a 100 MIPS eight--bit microcontroller, promotes the concept of
“virtual peripherals,” peripheral functions that are implemented in software. Lucent Technologies has recently announced a phone chip set that offers features in software that can only exist because the product is based on an inexpensive 100 MIPS DSP.
The appeal of implementing functions in software is growing. You can add new features to a product family by modifying the software and produce several versions without changing the hardware. As the price of flash memory drops, this alternative will become
increasingly attractive.
The trend of realizing features in software that once could be done only in hardware will continue. Next month’s issue of
Embedded Systems Programming
will feature an article that tells how to implement a purchased software modem in a consumer device, thus adding a needed feature at an acceptable price. It further demonstrates that IP isn’t just for hardware anymore.
Lindsey Vereen
lvereen@cmp.com
