Fpga &;cpld(by alok singh)

Introduction to FPGA &
CPLD Devices
BY(ALOK SINGH kanpur)
alok.lpu@yahoo.com
04/20/18 1

Hierarchy of Logic Implementations
Acronyms
SPLD = Simple Prog. Logic Device
PAL = Prog. Array of Logic
CPLD = Complex PLD
FPGA = Field Prog. Gate Array
ASIC = Application Specific IC
Common Resources
Configurable Logic Blocks (CLB)
• Memory Look-Up Table (LUT)
• AND-OR planes
• Simple gates
Input / Output Blocks (IOB)
• Bidirectional, latches, inverters, pullup/pulldowns
Interconnect or Routing
• Local, internal feedback, and global
Logic
Standard
Logic
ASIC
Programmable
Logic Devices
(FPLDs)
Gate
Arrays
Cell-Based
ICs
Full Custom
ICs
CPLDsSPLDs
(e.g., PALs) FPGAs

• designs must be sent
for expensive and time
consuming fabrication
in semiconductor foundry
• bought off the shelf (ready to use)
and reconfigured by
designers themselves
Two competing implementation approaches
ASIC
Application Specific
Integrated Circuit
FPGA
Field Programmable
Gate Array
• designed all the way
from behavioral description
to physical layout
• no physical layout design;
design ends with
a bitstream used
to configure a device
04/20/18 3

BlockRAMs
BlockRAMs
Configurable
Logic
Blocks
I/O
Blocks
What is an FPGA?
Block
RAMs
04/20/18 4

Which Way to Go?
Off-the-shelf
Low development cost
Short time to market
Reconfigurability
High performance
ASICs FPGAs
Low power
Low cost in
high volumes
(ready-to-use)
04/20/18 5

Other FPGA Advantages
• Manufacturing cycle for ASIC is very costly, lengthy and engages lots
of manpower
• Mistakes not detected at design time have large impact on development time
and cost
• FPGAs are perfect for rapid prototyping of digital circuits
• Easy upgrades like in case of software
• Unique applications
• reconfigurable computing
04/20/18 6

Major FPGA Vendors
SRAM-based FPGAs
• Xilinx, Inc.
• Altera Corp.
• Atmel
• Lattice Semiconductor
Flash & antifuse FPGAs
• Actel Corp.
• Quick Logic Corp.
Share over 60% of the market
04/20/18 7

Xilinx FPGA Families
• Old families
• XC3000, XC4000, XC5200
• Old 0.5µm, 0.35µm and 0.25µm technology. Not recommended for modern designs.
• High-performance families
• Virtex (0.22µm)
• Virtex-E, Virtex-EM (0.18µm)
• Virtex-II, Virtex-II PRO (0.13µm)
• Virtex-4 (0.09µm)
• Low Cost Family
• Spartan/XL – derived from XC4000
• Spartan-II – derived from Virtex
• Spartan-IIE – derived from Virtex-E
• Spartan-3
04/20/18 8

 CPLD
 Complex Programmable Logic Devices (CPLD)
 SPLDs (PLA, PAL) are limited in size due to the small number of input
and output pins and the limited number of product terms
 Combined number of inputs + outputs < 32 or so
 CPLDs contain multiple circuit blocks on a single chip
 Each block is like a PAL: PAL-like block
 Connections are provided between PAL-like blocks via an interconnection network
that is programmable
 Each block is connected to an I/O block as well

 Structure of a CPLD
PAL-like block
(MACRO CELL)
I/Oblock
I/Oblock
I/Oblock
I/Oblock
Interconnection wires
PAL-like block
PAL-like blockPAL-like block
(MACRO CELL)(MACRO CELL)
(MACRO CELL)

Examples of CPLDs and high pin count package types
Examples of CPLDsExamples of CPLDs

 Internal Structure of a PAL-like Block
 Includes macrocells
 Usually about 16 each
 Fixed OR planes
 OR gates have fan-in
between 5-20
 XOR gates provide
negation ability
 XOR has a control
input
D Q
D Q
D Q
PAL-like block
PAL-like block

 More on PAL-like Blocks
 CPLD pins are provided to control XOR, MUX, and tri-state gates
 When tri-state gate is disabled, the corresponding output pin can be used
as an input pin
 The associated PAL-like block is then useless
 The AND plane and interconnection network are programmable
 Commercial CPLDs have between 2-100 PAL-like blocks

 Programming a CPLD
 CPLDs have many pins – large ones have > 200
 Removal of CPLD from a PCB is difficult without breaking the pins
 Use ISP (in system programming) to program the CPLD
 JTAG (Joint Test Action Group) port used to connect the CPLD to a computer

 Example CPLD
 Use a CPLD to implement the function
 f = x1x3x6' + x1x4x5x6' + x2x3x7 + x2x4x5x7
D Q
PAL-like block
(from interconnection wires)
x1 x2 x3 x4 x5 x6 x7 unused
0
0 1
f

 FPGA
 SPLDs and CPLDs are relatively small and useful for simple logic
devices
 Up to about 20000 gates
 Field Programmable Gate Arrays (FPGA) can handle larger circuits
 No AND/OR planes
 Provide logic blocks, I/O blocks, and interconnection wires and switches
 Logic blocks provide functionality
 Interconnection switches allow logic blocks to be connected to each other and to the
I/O pins

 Structure of an FPGA
I/O block
I/O block
I/Oblock
I/Oblock
logic block
interconnection
switch

 LUTs
 Logic blocks are implemented using a lookup table (LUT)
 Small number of inputs, one output
 Contains storage cells that can be loaded with the desired values
 A 2 input LUT uses 3 MUXes
to implement any desired function
of 2 variables
 Shannon's expansion at work!
f
0/1
0/1
0/1
0/1
x1
x2

 Example 2 Input LUT
x1 x2 f
0 0 1
0 1 0
1 0 0
1 1 1
f = x1'x2' + x1x2, or using Shannon's expansion:
f = x1'(x2') + x1(x2)
= x1'(x2'(1) + x2(0)) + x1(x2'(0) + x2(1))
f
1
0
0
1
x 1
x 2

 3 Input LUT
 7 2x1 MUXes and
8 storage cells are
required
 Commercial LUTs have
4-5 inputs, and 16-32
storage cells f
0/1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
x 2
x 3
x 1

 Example FPGA
 Use an FPGA with 2 input LUTS to implement the function f = x1x2 + x2'x3
 f1 = x1x2
 f2 = x2'x3
 f = f1 + f2
0
1
0
0
0
1
1
1
0
0
0
1
x1
x2
x2
x3
f 1
f 2
f 1 f 2
f
x1
x2
x3 f

 Another Example FPGA
 Use an FPGA with 2 input LUTS to implement the function f = x1x3x6' +
x1x4x5x6' + x2x3x7 + x2x4x5x7
 Fan-in of expression is too large for FPGA (this was simple to do in a CPLD)
 Factor f to get sub-expressions with max fan-in = 2
 f = x1x6'(x3 + x4x5) + x2x7(x3 + x4x5)
= (x1x6' + x2x7)(x3 + x4x5)
 Could use Shannon's expansion instead
 Goal is to build expressions out of 2-input LUTs

0
0
0
1
0
1
1
1
x4
x5
A
B
C
D
x1
x6
x4 f
0
1
1
1
0
0
0
1
x3
C
D
E
E
f
x2
x7
x5 x3
0
0
0
1
x2
x7
B
0
0
1
0
x1
x6
A
 FPGA Implementation
 f = (x1x6' + x2x7)(x3 + x4x5)

Xilinx9500 series CPLD Features:
• High-performance
• 5 ns pin-to-pin logic delays on all pins
• Freq fCNT to 125 MHz
• Large density range: 36 to 288 macrocells with 800 to 6,400 usable gates
• 5V in-system programmable
• 90 product terms drive any or all of 18 macrocells
• Global and product term clocks, output enables, set and reset signals
• Extensive IEEE Std 1149.1 boundary-scan (JTAG) support
• Programmable power reduction mode in each macrocell
• Slew rate control on individual outputs
• User programmable ground pin capability
• Extended pattern security features for design protection
• High-drive 24 mA outputs
04/20/18 24

25
XilinxXilinx
Product
XC7000 Series
XC7200 Series
– Each block has 9 macrocells
– Each macrocells includes two OR-gates
– Each OR-gates is input to a two-bit ALU
XC7300 Series : Enhanced version of 7200
XC9500 Series
In-system programmability

26
XC9536 XC9572 XC95108 XC95144 XC95216 XC95288
Macrocells 36 72 108 144 216 288
Usable Gates 800 1,600 2,400 3,200 4,800 6,400
Registers 36 72 108 144 216 288
t PD (ns) 5 7.5 7.5 7.5 10 10
t SU (ns) 3.5 4.5 4.5 4.5 6.0 6.0
t CO (ns) 4.0 4.5 4.5 4.5 6.0 6.0
f CNT (MHz) 100 125 125 125 111.1 111.1
f SYSTEM (MHz) 100 83.3 83.3 83.3 66.7 66.7
Note:
f CNT = Operating frequency for 16-bit counters
f SYSTEM = Internal operating frequency for general purpose system designs spanning multiple FBs.
Xilinx: XC9500 Device FamilyXilinx: XC9500 Device Family

27
(a) CPLDinaQuadFlat Pack (QFP) package
Printed
circuit board
To computer
(b) JTAGprogramming
CPLD Packaging and Programming
(a) a CPLD in a Quad Flat Pack
(QFP) IC package
(b) Set up for programming the
PCB-mounted CPLD using JTAG
(a)
(b)

28
XSA-100 BoardXSA-100 Board
logic density of 100,000logic density of 100,000
gates with Spartan-IIgates with Spartan-II
FPGAFPGA
16-Mbyte synchronous16-Mbyte synchronous
DRAMDRAM
XC9572 interface CPLDXC9572 interface CPLD

29
XSA-100 BoardXSA-100 Board
External connections to the XSAExternal connections to the XSA
board.board.
Parallel port for programmingParallel port for programming
External power supplyExternal power supply
VGA port to display signalsVGA port to display signals
PS/2 port for pointing operationsPS/2 port for pointing operations

30
XilinxXilinx
Architecture of Xilinx 9500 CPLDsArchitecture of Xilinx 9500 CPLDs

31
Proprietary systems are
beginning to give way to a
standard from the Joint
Test Action Group
(JTAG)

32
Each XC9500 device is a subsystem consisting of multiple Function Blocks (FBs)
and I/O Blocks (IOBs) fully interconnected by the FastCONNECT switch matrix.
The IOB provides buffering for device inputs and outputs. Each FB provides
programmable logic capability with 36 inputs and 18 outputs.
The FastCONNECT switch matrix connects all FB outputs and input signals to the
FB inputs. For each FB, 12 to 18 outputs (depending on package pin-count) and
associated output enable signals drive directly to the IOBs.

33
Each Function Block is comprised of 18 independent macrocells, each
capable of a combinatorial or registered function. The FB also receives
global clock, output enable, and set/reset signals.
The FB generates 18 outputs that drive the FastCONNECT switch
matrix. These 18 outputs and their corresponding output enable signals
also drive the IOB.
Logic within the FB is implemented using a sum-of-products
representation. Thirty-six inputs provide 72 true and complement
signals into the programmable AND-array to form 90 product terms.
Any number of these product terms, up to the 90 available, can be
allocated to each macrocell by the product term allocator.

34
Each FB (except for the XC9536) supports local feedback paths that allow any number of
FB outputs to drive into its own programmable AND-array without going outside the FB.
These paths are used for creating very fast counters and state machines where all state
registers are within the same FB.

35
Each XC9500 macrocell may be individually configured for a combinatorial or
registered function. The macrocell and associated FB logic is shown in Figure.
Five direct product terms from the AND-array are available for use as primary data
inputs (to the OR and XOR gates) to implement combinatorial functions, or as control
inputs including clock, set/reset, and output enable. The product term allocator
associated with each macrocell selects how the five direct terms are used.
The macrocell register can be configured as a D-type or T-type flip-flop, or it may be
bypassed for combinatorial operation. Each register supports both asynchronous set
and reset operations. During power-up, all user registers are initialized to the user-
defined preload state (default to 0 if unspecified).

36
MacrocellMacrocell
f 1
back to AND plane
D Q
Clock
Select
Enable
Flip-flop
OR gate from PAL 0
1

37

38
All global control signals are available to each individual macrocell, including clock, set/reset, and output
enable signals.
As shown in Figure 4, the macrocell register clock originates from either of three global clocks or a product
term clock. Both true and complement polarities of a GCK pin can be used within the device. A GSR input is
also provided to allow user registers to be set to a user-defined state.

39
The FastCONNECT switch matrix connects signals to the FB inputs, as
shown in Figure. All IOB outputs (corresponding to user pin inputs)
and all FB outputs drive the FastCONNECT matrix. Any of these (up to
a FB fan-in limit of 36) may be selected, through user programming, to
drive each FB with a uniform delay.
The FastCONNECT switch matrix is capable of combining multiple
internal connections into a single wired-AND output before driving the
destination FB. This provides additional logic capability and increases
the effective logic fan-in of the destination FB without any additional
timing delay. This capability is available for internal connections
originating from FB outputs only. It is automatically invoked by the
development software where applicable.

40

41
The I/O Block (IOB) interfaces between the internal logic and the
device user I/O pins. Each IOB includes an input buffer, output driver,
output enable selection multiplexer, and user programmable ground
control. See Figure 10 for details.
The input buffer is compatible with standard 5 V CMOS, 5 V TTL and
3.3 V signal levels. The input buffer uses the internal 5 V voltage
supply (V CCINT ) to ensure that the input thresholds are constant and
do not vary with the V CCIO voltage.

42
XC9500 devices are programmed in-system via a standard 4-pin JTAG
protocol. In-system programming offers quick and efficient design
iterations and eliminates package handling.
The Xilinx development system provides the programming data
sequence using a Xilinx download cable, a third-party JTAG
development system, JTAG-compatible board tester, or a simple micro-
processor interface that emulates the JTAG instruction sequence.

43
XC9500 devices incorporate advanced data security features which fully protect the
programming data against unauthorized reading or inadvertent device erasure/reprogramming.
Table 3 shows the four different security settings available.
The read security bits can be set by the user to prevent the internal programming pattern from
being read or copied. When set, they also inhibit further program operations but allow device
erase. Erasing the entire device is the only way to reset the read security bit.
The write security bits provide added protection against accidental device erasure or
reprogramming when the JTAG pins are subject to noise, such as during system power-up.
Once set, the write-protection may be deactivated when the device needs to be reprogrammed
with a valid pattern.

44
Basic Timing Model

XC9500 Product term allocator and macrocell
04/20/18 45

(Not having a fine texture)
04/20/18 47

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