04-08-2012, 11:15 AM
Telecommunications Applications With the TMS320C5x DSPs
[attachment=30158]
Overview
The use of programmable digital signal processors (DSPs) is growing rapidly in telecommunication
applications. Conventional wire-line telephony applications were among the earliest adopters of digital
signal processing technologies. High-speed telephone-line modem products use more general-purpose
DSPs than most other industries, and recent growth of personal and mobile communication services has
spurred new interest in high-performance DSPs. With the ongoing integration of mobile communication
services and portable computer applications, the role of programmable DSPs in emerging products is
expanding. Today, digital signal processors are moving from high-end, low-volume applications to
mainstream consumer applications.
Programmable Versus Hard-Wired Solutions
DSPs are following the path of microprocessors in terms of performance and on-chip integration. At the
same time, users of DSPs are concerned about power consumption. As the communications industry
improves portable applications, low power and high integration become key design care-abouts. Generally
speaking, a product design is constrained by one or more of the following key design goals, not necessarily
with equal importance:
• Power consumption
• Product form factor
• Upgradability
• Cost of product
• Cost of design
• System integration
These design goals play key roles in selecting a programmable versus function-specific or hard-wired DSP
solution.
Newer generation DSPs are addressing these concerns. They support various low-power and power-down
modes along with clock control options to help meet power goals. System integration and form-factor goals
are often interrelated. With high on-chip integration of peripherals and memory, modern DSPs are
well-suited for portable applications in which product form factor is extremely important. In Part VIII,
“The PCMCIA DSP Card: An All-in-One Communications System”, page 237, describes a DSP system
based on Personal Computer Memory Card Interface Association (PCMCIA) type II card specifications.
Many DSPs are now available in thin low-profile plastic packages, which are ideal for surface-mount
applications.
Fixed-Point Versus Floating-Point Solutions
Typically, floating-point DSPs are used in high-end, high-performance telecom applications such as video
conferencing, network packet switching, cellular base stations, etc. Floating-point DSPs offer large
dynamic range, a fast floating-point computation engine, and large-memory addressability. Due to wider
instruction word size, they support more addressing modes and higher execution unit parallelism as well.
Floating-point support and large operand dynamic range result in an ease of transition from simulation
environment to real-time implementation. A more orthogonal instruction set helps in providing efficient
high-level language code generation tools.
TMS320 Fixed-Point DSPs
The three generations of TMS320 fixed-point DSPs — TMS320C1x, TMS320C2x, and TMS320C5x —
have a 16-bit architecture with a 32-bit ALU and accumulator. They are based on Harvard architecture with
separate buses for program and data, allowing instructions and operands to be fetched in parallel. They also
feature a 16 16-bit hardware multiplier for single-cycle multiply operations, and a hardware stack for
fast interrupt response time. An overflow saturation mode prevents wraparound. Most of the instructions
are executed in a single cycle. Performance currently ranges from 3.5 to 40 MIPS (million instructions per
second). Even higher performance DSPs will become available in the near future.
[attachment=30158]
Overview
The use of programmable digital signal processors (DSPs) is growing rapidly in telecommunication
applications. Conventional wire-line telephony applications were among the earliest adopters of digital
signal processing technologies. High-speed telephone-line modem products use more general-purpose
DSPs than most other industries, and recent growth of personal and mobile communication services has
spurred new interest in high-performance DSPs. With the ongoing integration of mobile communication
services and portable computer applications, the role of programmable DSPs in emerging products is
expanding. Today, digital signal processors are moving from high-end, low-volume applications to
mainstream consumer applications.
Programmable Versus Hard-Wired Solutions
DSPs are following the path of microprocessors in terms of performance and on-chip integration. At the
same time, users of DSPs are concerned about power consumption. As the communications industry
improves portable applications, low power and high integration become key design care-abouts. Generally
speaking, a product design is constrained by one or more of the following key design goals, not necessarily
with equal importance:
• Power consumption
• Product form factor
• Upgradability
• Cost of product
• Cost of design
• System integration
These design goals play key roles in selecting a programmable versus function-specific or hard-wired DSP
solution.
Newer generation DSPs are addressing these concerns. They support various low-power and power-down
modes along with clock control options to help meet power goals. System integration and form-factor goals
are often interrelated. With high on-chip integration of peripherals and memory, modern DSPs are
well-suited for portable applications in which product form factor is extremely important. In Part VIII,
“The PCMCIA DSP Card: An All-in-One Communications System”, page 237, describes a DSP system
based on Personal Computer Memory Card Interface Association (PCMCIA) type II card specifications.
Many DSPs are now available in thin low-profile plastic packages, which are ideal for surface-mount
applications.
Fixed-Point Versus Floating-Point Solutions
Typically, floating-point DSPs are used in high-end, high-performance telecom applications such as video
conferencing, network packet switching, cellular base stations, etc. Floating-point DSPs offer large
dynamic range, a fast floating-point computation engine, and large-memory addressability. Due to wider
instruction word size, they support more addressing modes and higher execution unit parallelism as well.
Floating-point support and large operand dynamic range result in an ease of transition from simulation
environment to real-time implementation. A more orthogonal instruction set helps in providing efficient
high-level language code generation tools.
TMS320 Fixed-Point DSPs
The three generations of TMS320 fixed-point DSPs — TMS320C1x, TMS320C2x, and TMS320C5x —
have a 16-bit architecture with a 32-bit ALU and accumulator. They are based on Harvard architecture with
separate buses for program and data, allowing instructions and operands to be fetched in parallel. They also
feature a 16 16-bit hardware multiplier for single-cycle multiply operations, and a hardware stack for
fast interrupt response time. An overflow saturation mode prevents wraparound. Most of the instructions
are executed in a single cycle. Performance currently ranges from 3.5 to 40 MIPS (million instructions per
second). Even higher performance DSPs will become available in the near future.