Hybrid 32-Bit MCUs Master Memory, Power, And Price

ROLL YOUR OWN
Off-the-shelf MCUs address most developers' needs, but custom implementations are often more cost-effective and provide better performance. Custom MCUs are available from a large number of sources, including those with standard 32-bit MCU parts. However, Tensilica and Arc are dedicated to custom 32-bit implementations.

Tensilica's Xtensa architecture implements a five-stage pipeline with user-selectable datapath widths up to 1024 bits. Tensilica Instruction Extensions (TIE) enhances Xtensa's instruction set and links instructiosn to custom logic.

Arc takes a similar approach, offering a range of standard configurations that can be combined on one chip. These include the standard ARCtangent architecture as well as ARCtangent for DSP and the ArcLite microRISC 8-bit RISC core. Mixing multiple processors on a chip allows each to be pruned down to the minimum requirements while optimizing functionality.

David Fritz, VP of technical marketing, says that Arc's IPShield security support improves throughput by a factor of 20 for Advanced Encryption Standard (AES) when implemented as ARCtangent instructions. Configuration for most features is a matter of selecting options from a dialog box (Fig. 5).

The key to both company's solutions is the software that encompasses the package. Compilers, debuggers, and integration development environments are customized based upon the hardware design.

The plethora of 8- and 16-bit MCUs is primarily due to the vast number of peripheral and memory combinations available. The diversity of 32-bit MCUs is augmented by the wide range of architectures, acceleration methods, and multiprocessing that's rarely found in their smaller cousins. It makes the developer's job of finding the right high-performance component for a project difficult but interesting.