32bit RISC cores take on 8bit in size

Paul Boughton

Several new 32bit processor architectures are looking to take on 8bit processors in size and system cost and target a market of billions of units.

IP licensing company CAST has signed up a new 32bit RISC processor core that is as small as an 8it processor.

The APS has been developed by Corex in Grenoble, France, in just 7000 gates, comparable to an 8051 core and compared to the 32bit ARM Cortex M3 microcontroller with 33000 gates. The APS is a Harvard architecture with 5 to 7 stage execution pipeline and is aimed at integration into ASICs.

There are two versions - one with a full 32bit core and a slightly larger one that can use both 32bit and 16bit instructions to keep the system memory size and cost down.

The core has also been optimised with the C compiler, and tools are emerging from third parties in the CAST network such as MicroCross.

Even so, the M3 is comparable to an 8bit processor in system size, requiring a system memory less than half the size as a result of the code density by using the Thumb 2 instruction set.

ARM has also launched its mainstream processor core that will replace the ARM9 in cell phones, hard disk drives and in car electronics.

The Cortex R4 is a dual issue, 8 stage pipeline RISC processor that is optimised to use slower system memory but still provide 400MHz performance. It will run both 32bit ARM instructions and the Thumb 2 16bit instructions that keep memory size down. The core can also be configured with different tightly coupled memories and interfaces at the synthesis time for different users.

“We see pretty much all our users recompiling for Thumb 2 because they like the code density,” said Richard York, product manager at ARM. “The Thumb code is 20 per cent faster and the processor is very close to the area of the ARM9 with 40 per cent more performance and the ability to use the third generation AXI interconnect rather than AHB,” he said.

There are already three licensees with the first four products taping out by the end of the year, he says.

Freescale is also tackling the 8bit market, but with a new 8bit core that will be pin compatible with future 16 and 32bit processors.

The RS08 8bit core is a simplified version of Freescale's high-performance, low-power HCS08 architecture, and the resulting 6pin MC9RS08KA microcontroller family is designed for applications with extreme space and price constraints such as traditional electro-mechanical designs and portable applications ranging from motor control to use-and-toss health care products.

“Freescale is positioned to compete aggressively in the ultra-low-end 8-bit market,” said Fred Zieber, founder and president of market researchers Pathfinder Research. “This product signals to the market Freescale's dedication to offering a breadth of MCU products suited for any and all customer needs.”

The 43cent controllers provide up to 2K flash and 63Bytes of RAM as well as reprogrammable flash across voltage ranges and performs up to 10 MHz at 1.8V. The product features a voltage regulator that minimizes voltage variation to logic and keeps voltage supply (Vdd) lower, reducing overall power consumption.

“The tiny KA is proof that small devices can be packed with possibilities,” said Mike McCourt, vice president and general manager of Freescale's Microcontroller Division. “This move to the ultra-low-end combined with Freescale's tools and support demonstrates that we have listened closely to our customer base and are providing them the fastest, easiest and most accessible solutions in the market.”