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Vodafone Chair Mobile Communications Systems, Prof. Dr.-Ing. G. Fettweis
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Digital Signal Transmission Lab
SS 08
Oliver Arnold
Steffen Kunze
TU Dresden, 4/29/2008 Slide 2
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Introduction
Hardware
Why to use digital signal processing?
General introduction to DSPs
The TMS320C6711 DSP
Architecture Overview
Peripherals
DSK6711 evaluation board - Software
Code Composer Studio
DSP/BIOS
Multi-channel Buffered Serial Port (McBSP)
TU Dresden, 4/29/2008 Slide 3
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Hardware
TU Dresden, 4/29/2008 Slide 4
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Digital Signal Processing (DSP)
Consumer Audio
Stereo A/D, D/A
PLL
Mixers
Multimedia
Stereo audio
Imaging
Graphics palette
Voltage regulation
Wireless / Cellular
Voice-band audio
RF codecs
Voltage regulation
HDD
PRML read channel
MR pre-amp
Servo control
SCSI tranceivers
Automotive
Digital radio A/D/A
Active suspension
Voltage regulation
DTAD
Speech synthesizer
Mixed-signal
processor
DSP:
Technology
Enabler
TU Dresden, 4/29/2008 Slide 5
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System Considerations
Performance
Performance
Interfacing
Interfacing
Power
Power
Size
Size
Ease
Ease
-
-
of Use
of Use
•
•
Programming
Programming
•
•
Interfacing
Interfacing
•
•
Debugging
Debugging
Integration
Integration
•
•
Memory
Memory
•
•
Peripherals
Peripherals
Cost
Cost
•
•
Device cost
Device cost
•
•
System cost
System cost
•
•
Development cost
Development cost
•
•
Time to market
Time to market
TU Dresden, 4/29/2008 Slide 6
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Why Go Digital?
Digital signal processing techniques are now
so powerful that sometimes it is extremely
difficult, if not impossible, for analogue signal
processing to achieve similar performance.
Examples:
FIR filter with linear phase
Adaptive filters
TU Dresden, 4/29/2008 Slide 7
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Why Go Digital?
Analogue signal processing is achieved by
using analogue components such as:
Resistors
Capacitors
Inductors
The inherent tolerances associated with
these components, temperature, voltage
changes and mechanical vibrations can
dramatically affect the effectiveness of the
analogue circuitry
TU Dresden, 4/29/2008 Slide 8
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Why Go Digital?
With DSP? - It is easy to:
Change applications
Correct applications
Update applications
Additionally DSPs reduce:
Noise susceptibility
Chip count
Development time
Cost
Power consumption
TU Dresden, 4/29/2008 Slide 9
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General Introduction to DSPs
TU Dresden, 4/29/2008 Slide 10
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What Problem Are We Trying To Solve?
Digital sampling of
an analog signal:
A
t
Most DSP algorithms can be
expressed as:
count
i = 1
Y = Σ a
i
* x
i
for (i = 1; i < count; i++){
sum += m[i] * n[i]; }
DAC
xY
ADC
DSP
TU Dresden, 4/29/2008 Slide 11
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What are the typical DSP algorithms?
The Sum of Products (SOP) is the key element in
most DSP algorithms:
0
() ( )
M
k
k
yn axn k
=
=
−
∑
∑∑
==
−+−=
N
k
k
M
k
k
knybknxany
10
)()()(
∑
=
−=
N
k
knhkxny
0
)()()(
∑
−
=
−=
1
0
])/2(exp[)()(
N
n
nkNjnxkX
π
() ()
∑
−
=
⎥
⎦
⎤
⎢
⎣
⎡
+=
1
0
12
2
cos).().(
N
x
xu
N
xfucuF
π
Discrete Cosine Transform
Discrete Fourier Transform
Convolution
Infinite Impulse Response Filter
Finite Impulse Response Filter
EquationAlgorithm
TU Dresden, 4/29/2008 Slide 12
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Use a DSP processor when the following
are required:
Cost saving
Smaller size
Low power consumption
Processing of many “high” frequency signals in
real-time
Use a GPP processor when the following
are required:
Large memory
Advanced operating systems
Why do we need DSP processors?
TU Dresden, 4/29/2008 Slide 13
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Hardware vs. Microcode multiplication
DSP processors are optimized to perform
multiplication and addition operations.
Multiplication and addition are done in
hardware and in one cycle.
Example: 4-bit multiply (unsigned).
1011
1011
x 1110
x 1110
1011
1011
x 1110
x 1110
Hardware
Hardware
Microcode
Microcode
10011010
10011010
0000
0000
1011.
1011.
1011..
1011..
1011...
1011...
10011010
10011010
Cycle 1
Cycle 1
Cycle 2
Cycle 2
Cycle 3
Cycle 3
Cycle 4
Cycle 4
Cycle 5
Cycle 5
TU Dresden, 4/29/2008 Slide 14
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General Purpose DSP vs. DSP in ASIC
Application Specific Integrated Circuits
(ASICs) are semiconductors designed for
dedicated functions.
The advantages and disadvantages of using
ASICs are listed below:
Advantages
Advantages
•
•
High throughput
High throughput
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•
Lower silicon area
Lower silicon area
•
•
Lower power consumption
Lower power consumption
•
•
Improved reliability
Improved reliability
•
•
Reduction in system noise
Reduction in system noise
•
•
Low overall system cost
Low overall system cost
Disadvantages
Disadvantages
•
•
High investment cost
High investment cost
•
•
Less flexibility
Less flexibility
•
•
Long time from design to
Long time from design to
market
market
TU Dresden, 4/29/2008 Slide 15
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Floating vs. Fixed point processors
Applications which require:
High precision
Wide dynamic range
High signal-to-noise ratio
Ease of use
ÎNeed a floating point processor
Drawback of floating point processors:
Higher power consumption
Usually higher cost
Usually slower than fixed-point counterparts and
larger in size
TU Dresden, 4/29/2008 Slide 16
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TMS320C6711 Architectural Overview
TU Dresden, 4/29/2008 Slide 17
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General DSP System Block Diagram
P
E
R
I
P
H
E
R
A
L
S
Central
Processing
Unit
Internal Memory
Internal Buses
External
Memory
TU Dresden, 4/29/2008 Slide 18
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‘6711 CPU Overview
Specification
Clock Rate: 100/150 MHz Î 600/900 MFLOPS
0.18-μm/5-Level Metal Process – CMOS Technology
CPU has got two Datapaths, altogether:
Four ALUs (Floating- and Fixed-Point)
Two ALUs (Fixed-Point)
Two Multipliers (Floating- and Fixed-Point)
Load-Store Architecture
2*16 32-Bit General-Purpose Registers
TU Dresden, 4/29/2008 Slide 19
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‘6711 CPU Overview
VelociTI Î advanced very-long instruction words (VLIW)
Program Memory Width is 256 Bit
Up to 8 32-Bit instructions can be executed in parallel/Cycle
16, 32 and 40 bit fixed point operands
32 and 64 bit floating point operands
Instruction parallelism is detected at compile-time
no data dependency checking is done in Hardware.
Instruction Packing Reduces Code Size
All operations work on registers
Memory Architecture
4K-Byte L1P Program Cache (Direct Mapped)
4K-Byte L1D Data Cache (2-Way Set-Associative)
64K-Byte L2 Unified Mapped RAM/L2 Cache (Flexible Data/Program
Allocation)
TU Dresden, 4/29/2008 Slide 20
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Functional Block and CPU Diagram
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