Soft-Core Processors for Embedded Systems

A soft-core processor is a hardware description language (HDL) model of a specific processor (CPU) that can be customized for a given application and synthesized for an ASIC or FPGA target. In many applications, soft-core processors provide several advantages over custom designed processors such as reduced cost, flexibility, platform independence and greater immunity to obsolescence. Embedded systems are hardware and software components working together to perform a specific function. Usually they contain embedded processors that are often in the form of soft-core processors that execute software code. This paper presents a survey of soft-core processors that are used in embedded systems. Several soft-core processors available from commercial vendors and open-source communities are reviewed and compared based on major architectural features. In addition, several real world examples of embedded systems that employ soft-core processors are summarized. As the complexity of embedded systems continues to increase, it is expected that the usage of customizable soft-core processors will become more widespread.