Transcript CS 2204 Fall 2005 - NYU Polytechnic School of Engineering

CS 2204 Spring 2006
Experiment 2
Lab 4

Xilinx Project Development Steps
 Develop the schematic
Design the schematic
 Do integrity tests
 Test the schematic via functional simulations

 Do a Xilinx implementation

It maps the components to the CLBs of the chip
 Do timing simulations to test the schematic

It generates the bit file
 Download the bit file to the FPGA
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It programs the chip
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Developing a digital product
 A new chip
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Which gates & FFs and how many is determined by
 Speed, cost, power, etc. goals of the digital product
• FPGAs are used to test the new chip
 Besides the application (major operations) and available
components of the technology chosen
 A new PCB

Which chips and how many is determined by
 Speed, cost, power, etc. goals of the digital product
 Besides the application (major operations) and available
chips of the technology chosen
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Digital circuits consist of gates and FFs
 FFs consist of gates

Digital circuits consist of gates !
Gates are on chips !
 Gates are implemented by electronic
components on chips :

 Transistors, capacitors, resistors, diodes,…
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Digital circuits consist of gates and FFs
 FFs consist of gates
D FF implementation
via gates
D FF
From ON Semiconductor LS TTL Data Manual
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Digital circuits consist of gates
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Gates are on chips !
Electronic components on chips implement
gates:
 Transistors, capacitors, diodes, resistors,…
NAND gate
implementation
via electronic
components
74 LS00
Quad
2-input
NAND
Gate
chip
From ON Semiconductor LS TTL Data Manual
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Transistors are the main component and
used as switches to implement gates
 A switch is open or closed based on the
control input value :
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Open when control is 0 :
Closed when control is 1
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0
1
0
1
1
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1
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Implementing AND, OR, NOT gates
k
k
m
AND
k.m
m
Implemented by 1
two switches
k.m
AND gate
k
k
OR
m
k+m
Implemented by
two switches
1
k+m
m
OR gate
k
NOT
k
Implemented by
one switch
k
1
0
NOT gate (inverter)
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2-to-1 MUX Implementation
a
b
y(a, b, c) = a.b + a.c
1
a
a
c
NOT
b
AND
OR
c
a
AND
y(a, b, c) = a.b + a.c
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Transistors, capacitors, resistors, diodes,…
have speed, cost, power, size,.. Properties,
determining same features of gates
 These properties depend on the technology used :
CMOS, BiCMOS, TTL, ECL,…


We then need to study substances used for chips
Electronic circuits that form the gates
Die
Transistors and other electronic
components are on the die
Today, there can be 200 million
transistors on a die
AAchip
chip
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Semiconductor substances and circuits
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Why are chips cheap today ?
Chips use semiconductors today
 Silicon is the most common semiconductor to
implement electronic components

sea sand is the source
 Other substances :
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Silicon Germanium, Gallium Arsenide
 More expensive but faster technologies
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Niobium
 Superconducting : the fastest.
 Not a semiconductor
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Gate Features
 Determined by switch features
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Speed
 Gate delay, tp, propagation delay : the time it
takes for the gate output to change after an
input is changed
a
a
b
y
b
y
tp
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1
a
Gate delays result in glitches
Do not use the output
during this time
a
0
ab
NOT
AND
b
1
ac
1
y
1
OR
a
c
1
AND
1
0
1
a
ac
ab
Glitch
(timing hazard)
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y
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Gate Features
 Cost : determined by the substance, family,
the number of inputs, etc.
 Power consumption : amount of electrical
power consumed in Watts
Determined by the substance, family, the number
of inputs, etc.
 Indirectly determines the density of the chip

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Gate Features
 Size : determined by the substance, family,
the number of inputs, the transistor circuit
 Fan-in : the number of inputs the gate has
a
b
c
y
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The fan-in is three
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Gate Features
 Fan-out : the number of gate inputs that can
be connected to a gate output
Determined by substance, family, the transistor
circuit, etc.
 If the fan-out is exceeded the output can be
damaged or its value may not be electrically
“strong” to be interpreted as 1 or 0

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Gate Features
 In order to increase the fan-out buffers are
used

Regular buffers (not input nor output buffers) are
used to increase the fan-out
 A buffer is an electronic circuit that is used to
electrically “drive” large currents, hence many inputs
• It can also have circuits to filter noise and
strengthen the signal
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Gate Features
 Increasing the fan-out
a
b
y
c
Use a buffer !
But, the input to output
delay is increased
.....
.....
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Digital Engineering Terminology
U1
U2
U2 has no Load
U2 output is not used
a
U4
b
U4 input has no driver
U4 input is not
connected to an output.
Its input value is Hi-Z
(High-Impedance) as
there is infinite
impedance (resistance)
into the U4 input so no
current can flow in
y
a
c
U3
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Multiple drivers on output y
U3 and U4 outputs are short circuited
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Silicon Technology Today
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Semiconductor Technology Today
 Moore’s Law holds since the 1960s :
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Every two years the number of transistors on a
chip doubles
 Every two years density of memory chips doubles
 Due to Moore’s law and other reasons :

Every two years the speed of microprocessors
doubles
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Silicon Technology Today
Multi-chip module (MCM, >1 die on chip) ? Giga Scale ?
Today
IBM 8-core Cell Processor with 234M transistors at
4GHz calculating 256B floating-point operations a
second
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Power Density Increasing Exponentially!
1000
Power doubles every 4 years
Rocket
Nozzle
Watts/cm 2
Nuclear Reactor
100
Pentium® 4
Pentium® III
Pentium® II
Hot plate
10
Pentium® Pro
Pentium®
i386
i486
1
1.5m
1m
0.7m
0.5m
0.35m
0.25m
0.18m
0.13m
0.1m
0.07m
Courtesy : “New Microarchitecture Challenges in the Coming Generations of CMOS Process Technologies” – Fred
Pollack, Intel Corp. Micro32 conference key note - 1999. Courtesy Avi Mendelson, Intel.
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Switch evolution
1) Electromechanical : relays
2) Electronic
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Vacuum tubes
Discrete transistors
Integrated circuit transistors
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SSI transistor
MSI transistor
LSI transistor
VLSI transistor
ULSI transistor
MCM transistor ? Giga Scale transistor ?
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Switch evolution
3) Optical switches ?
4) Molecular switches ?

Biological ?
5) ????
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Long Term Forecast
 SEMATECH : consortium of semiconductor
manufacturers from America, Asia and
Europe.
 SEMATECH predictions for year 2020 (from
its updated 2004 International Technology
Roadmap for Semiconductors, ITRS, study) :
 Clock speed : 73 GHz
 Number of transistors on a microprocessor
chip : 17 Billion
 256Gbit DRAM chips
 http://www.sematech.org
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Today’s Xilinx Work
 We will not develop a Xilinx project
 We will study (analyze) the term project and
modify portions of ppm schematics to learn
more about
The Xilinx software
 Study the Digilent board and the FPGA chip
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Today’s Xilinx Lab Work
1. Download the Experiment 2 project, exp2,
from the course web site to the CS2204
folder
2. Extract (unzip) exp2 in the same folder

The exp2 folder will be created for the project
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Today’s Xilinx Lab Work
3. Start the Xilinx Foundation software and
open the exp2 project in the exp2 folder
4. Study schematics 4 and 6
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
Enter the team information to all schematics
Study the 4-bit 2-to-1 MUX labeled U109
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Do a Hierarchy Push to see the implementation of the
4-bit 2-to-1 MUX by Xilinx
Confirm it consists of 4 (1-bit) 2-to-1 MUXes
Delete this MUX so it can be implemented on schematic
6 by using separate 4 2-to-1 MUXes
Study the (1-bit) 2-to-1 MUX on schematic 6

Label the wires so this MUX implements one of the
four MUXes of component 109
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Today’s Xilinx Lab Work
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Separate the output wire form its gate and do an
integrity test of this schematic sheet to see the
warning on the project manager window
Copy and paste this MUX and then label the
wires to implement the seocnd MUX of the 4-bit
2-to-1 MUX
Repeat the above step one more time
Draw the last 2-to-1 MUX yourself and label its
wires
Do an integrity test of this schematic sheet to
see if there are problems
Do a Xilinx IMPLEMENTATION and make sure
there are no errors
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Today’s Xilinx Lab Work


Take a look at the FPGA CLB usage by using the
FPGA Editor
Play the ppm game to complete the testing of our
design
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

Note that we did not do functional and timing
simulations step to test our circuit
We should have done them !
But, to simplify our learning today, we skipped them
today
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Today’s Xilinx Lab Work
5. Download the Ppm human vs. human project,
ppmhvsh, from the course web site to the
CS2204 folder
6. Extract (unzip) ppmhvsh in the same folder

The ppmhvsh folder will be created for the
project
7. Open the ppmhvsh project in the ppmhvsh
folder
8. Study the schematics
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Today’s Xilinx Lab Work
7. Do a Xilinx IMPLEMENTATION
8. Check the Implementation Log file to see
the number of warnings and the CLB
utilization
9. Download the bit file and play the game with
your partner
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Today’s Xilinx Lab Work will cover the
following Xilinx actions and concepts
 Placing team info on schematics
 Integrity tests
 Searching for components on the Xilinx
component library
 Copying and pasting schematics via ctrl-c and
ctrl-v
 The Select and Drag mode
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Today’s Xilinx Lab Work will cover the
following Xilinx actions and concepts
 Labeling wires and components
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Wire names follow application and block
partitioning naming requirements
 Except for wires that are connected IBUFs, OBUFs,
IPADs and OPADs
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Component names start with a U
 Except if it is a BUF, IBUF, OBUF, IPAD or OPAD
 Xilinx IMPLEMENTATONs

Observing the actual CLB and pad utilization
through the FPGA editor
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QUESTIONS ?
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