30-10-2012, 12:34 PM
Implementation of DSP Based CNC Machine supporting Card for interfacing high & low speed peripherals
Implementation of DSP.doc (Size: 11.45 MB / Downloads: 63)
ABSTRACT:
Digital signal processing uses special dedicated processors
to convert and interpret digital signals at very high speeds.
Digital Signal processing technology is enabling cost effective
and energy efficient control system design. The performance of
a DSP Architecture allows an intelligent approach to reduce the
complete system costs of digital motion control applications
using cheaper electrical motors, fewer sensors, and smaller
sizes of EMI filters. To provide also a cost optimal solution
Texas Instruments (TI") developed a single chip solution
combining the features of a Micro controller and the
performance advantages of a DSP core. This new - so-called
"DSP-Controller" delivers the real-time MIPS and the tightly
integrated peripherals to implement optimal control algorithms
with no cost penalty.
The incredible power of DSP for specific tasks is illustrated by
the fact that a DSP chip can execute a multiply-accumulate
(MAC) instruction, a fundamental operation, in a single clock
cycle. This same operation on a current Pentium processor chip
takes 11 clock cycles. Obviously a 120-MHz Pentium will still
take nearly four times as long as a 40-MHz DSP processor.
INTRODUCTION:
There are many varieties of DSP_s, and those choices
give control builders choices in their priorities for
control functions. The variety of DSP_s available means
that you as a user can obtain different control
performance, functions and capabilities to meet your
specific needs. DSP's speed allows better accuracy and
speed, yet is gentler on the machines it controls. What
can a high-speed control do for you? In simple terms, it gives
you the ability to finish one task faster and move along to the
next sooner. The combination of fast block transfer time with a
still faster servo cycle time ensures high data throughput, with
optimal accuracy.
In a broader sense, high speed creates many other benefits.
Improved accuracy, fit, finish and cutter life are the most
commonly reported peripheral benefits. Customers share the
benefits of high speed through the entire manufacturing
process, not just to produce more work in less time, but also
improving the accuracy and finish and reducing polishing and
fitting time. They do this by using the high speed to reduce the
step over and the tolerances. Tools simply last longer because
their chip load is much more consistent. The TMS320X28x
DSP includes the same advantages as the micro controller but
also offers higher speed, higher resolution, and capabilities to
implement the math-intensive algorithms to lower the system
cost. The high speed is attributable mainly to the dual bus of
the Harvard architecture as well as single-cycle multiplication
and addition instructions. One bus is used for data and the
other is used for program instructions. This saves time because
each is utilized simultaneously. Traditionally, cost has been a
potential disadvantage of the DSP solution, but this aspect has
diminished with the continuing decline of DSP costs. DSP
controllers enable enhanced, real-time algorithms as well as
sensor less control. The combination reduces the number of
components and optimizes the design of silicon to achieve a
system cost reduction.
High speed peripheral interfacing:
In AC servo drives, DSP_s are used for vector control of AC
motors. AC drives have complex control structures because of
the cross coupling of the three-phase currents. Vector rotation
techniques transform three-phase axes into rotating two-phase
dq axes. This two-phase rotation technique greatly simplifies
the analysis, making it equivalent to analyzing field-wound
DC motors. In UPSs and power converters, DSP_s are used for
PWM generation as well as power factor correction and
harmonic elimination. Advanced mathematical techniques can
be used to control the firing angles of the inverters, creating
low-harmonic PWM with unity power factors.
Emulator:
The software developed is first checked with emulator kit
eZdspTM F2812. The eZdspTM F2812 is a stand-alone
card--allowing evaluators to examine the TMS320F2812
digital signal processor (DSP) to determine if it meets their
application requirements. Furthermore, the module is an
excellent platform to develop and run software for the
TMS320F2812 processor. The eZdspTM F2812 is shipped
with a TMS320F2812 DSP. The eZdspTM F2812 allows
full speed verification of F2812 code. Two expansion
connectors are provided for any necessary evaluation
circuitry not provided on the as shipped configuration. To
simplify code development and shorten debugging time, a
C2000 Tools Code
Composer driver is provided. In addition, an onboard JTAG
connector provides interface to emulators, operating with
other debuggers to provide assembly language and _C_ high
level language debug.
EMP IC:
EPM IC is programmed using VHDL. It is used
to obtain chip select logic for different chips, for example
memory chips, graphics display controller etc. Port lines for
keyboard interfacing are also obtained.
Summary
This application report presents new controller architecture:
the DSP controller and its single chip solutions for the
control Applications. The TI TMS320x28x DSP controller
combines the performance of DSP architecture with the
optimized peripherals of a micro controller. With this DSP
controller, an intelligent control and sensor less approach
become possible. In addition, the System cost will be
reduced and the reliability of the entire system will be
improved & with the feature of programmable clock it is
possible to interface high as well as low speed peripherals
with the same DSP with maximum efficiency.