Interconnection of digital signal processor with program memory and external devices using a shared bus interface

Abstract

A circuit arrangement and method reduce the number of interconnects required for a digital signal processor by utilizing a shared bus to interconnect the digital signal processor to both a program memory and at least one external device. An instruction cache is utilized to cache selected instructions from a DSP program such that, whenever a cached copy of a DSP program instruction is available in the instruction cache, the cached copy can be fetched from the instruction cache instead of the program memory, thereby freeing the shared bus for performing an access to the external device. Caching of instructions and subsequent freeing of the shared bus for external device access may be conditioned on detection of a loop, whereby instructions from the loop are cached in the instruction cache and fetched during subsequent passes through the loop.