The C55x processor is designed for low power consumption, optimum performance,
and high code density. Its dual multiply±accumulate (MAC) architecture provides twice
the cycle efficiency computing vector products ± the fundamental operation of digital
signal processing, and its scaleable instruction length significantly improves the code
density. In addition, the C55x is source code compatible with the C54x. This greatly
reduces the migration cost from the popular C54x based systems to the C55x systems.
Some essential features of the C55x device are listed below:
Upward source-code compatible with all TMS320C54x devices.
64-byte instruction buffer queue that works as a program cache and efficiently
implements block repeat operations.
Two 17-bit by 17-bit MAC units can execute dual multiply-and-accumulate oper-
ations in a single cycle.
A40-bit arithmetic and logic unit (ALU) performs high precision arithmetic and
logic operations with an additional 16-bit ALU performing simple arithmetic
operations parallel to the main ALU.
Four 40-bit accumulators for storing computational results in order to reduce
Eight extended auxiliary registers for data addressing plus four temporary data
registers to ease data processing requirements.
Circular addressing mode supports up to five circular buffers.
Single-instruction repeat and block repeat operations of program for supporting
Detailed information about the TMS320C55x can be found in the manufacturer's
manuals listed in references [1±6].
2.2 TMS320C55x Architecture
The C55x CPU consists of four processing units: an instruction buffer unit (IU), a
program flow unit (PU), an address-data flow unit (AU), and a data computation unit
(DU). These units are connected to 12 different address and data buses as shown in
2.2.1 TMS320C55x Architecture Overview
Instruction buffer unit (IU): This unit fetches instructions from the memory into the
CPU. The C55x is designed for optimum execution time and code density. The instruc-
tion set of the C55x varies in length. Simple instructions are encoded using eight bits
INTRODUCTION TO TMS320C55X DIGITAL SIGNAL PROCESSOR