Introduction to CPLDs

Introduction to CPLDs
Complex Programmable
Logic Devices
CSET 4650
Field Programmable Logic Devices
Dan Solarek

Hierarchy of Logic Implementations
today’s focus
Standard
Logic
SPLDs
(e.g., PALs)
Logic
Programmable
Logic Devices
(FPLDs)
CPLDs
Acronyms
SPLD = Simple Prog. Logic Device
PAL = Prog. Array of Logic
CPLD = Complex PLD
FPGA = Field Prog. Gate Array
ASIC = Application Specific IC
Gate
Arrays
FPGAs
ASIC
Cell-Based
ICs
Full Custom
ICs
Common Resources
Configurable Logic Blocks (CLB)
Memory Look-Up Look Up Table (LUT)
AND-OR AND OR planes
Simple gates
Input / Output Blocks (IOB)
Bidirectional, latches, latches, inverters, pullup/pulldowns
pullup/pulldowns
Interconnect or Routing
Local, internal feedback, and global
2

PAL Architecture
Recall the PAL device
we studied earlier
PAL16L8
16 inputs
32 input AND gates
up to 8 output
functions
Outputs are selectable
between OR/NOR
3

GAL 16V8
An improved PAL
Each output is
programmable as
combinational or
registered
Also has
programmable
output polarity
4

GAL 16V8 Output Logic Macrocell
5

GAL Output Macrocells
4 to 1 MUX
00 = registered active low
01 = registered active high
10 = comb. active low
11 = comb. active high
2 to 1 MUX
Output feedback
External input
6

GAL Output Macrocells
Registered mode
7

GAL Output Macrocells
combinational mode
8

GAL 22V10
More inputs
More product terms
More flexibility
9

Why CPLDs? CPLDs
For larger applications, we could simply increase the number
of inputs and outputs in a conventional SPLD …
e.g., 16V8 → 20V8 → 22V10
why not keep this trend going → 32V16 → 128V64 ?
Problems:
n times the number of inputs and outputs requires n 2 as much chip
area → too costly
logic gets slower as number of inputs to AND array increases
Solution:
multiple PLDs with a relatively small (fast) programmable
interconnect
less general than a single large PLD, but we can use software to
partition our design into smaller PLD blocks
10

CPLDs
To create a CPLD device:
put a lot of Simple PLDs on the same chip
add “wires wires” between them whose connections can be
programmed (interconnect)
use fuse/EEPROM technology for the connections
Comparing CPLDs to FPGAs: FPGAs
CPLD devices are faster, cheaper and have fewer gates
than FPGAs
Meant for interfacing rather than heavy computation
Include built-in built in flash memory
FPGAs need external memory
11

PLCC Package With Socket
Printed circuit board
Plastic Leaded Chip Carrier
12

Examples of CPLDs
Examples of CPLDs and high pin count package types
13

Programming Complex PLDs
Some CPLDs are programmed using a PAL
programmer
this method becomes inconvenient for devices with
hundreds of pins
A second method of programming
solder the device to its printed circuit board
program it with a serial data stream from a personal
computer
the CPLD decodes the data stream and configures itself to
perform a specified logic function
14

Programming Complex PLDs
Each manufacturer has a proprietary name for its
CPLD programming system.
Lattice calls it "in-system "in system programming"
Proprietary systems are beginning to give way to a
standard from the Joint Test Action Group (JTAG)
15

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
(b)
Printed
circuit board
(a)
(a) CPLD in a Quad Flat Pack (QFP) package
(b) JTAG programming
To computer
16

XSA-100 XSA 100 Board
logic density of
100,000 gates
with Spartan-II Spartan II
FPGA
16-Mbyte 16 Mbyte
synchronous
DRAM
XC9572
interface CPLD
17

XSA-100 XSA 100 Board
External connections to
the XSA board.
Parallel port for
programming
External power supply
VGA port to display
signals
PS/2 port for pointing
operations
18

XSA-100 XSA 100 Board
XC9572XL interface CPLD
19

CPLD Structure and Alternate Names
A Simple PLD (or SPLD) is
usually a PLA or a PAL
A Complex PLD (CPLD) is
an arrangement of multiple
SPLD-like blocks on a single
chip.
Alternative names include:
enhanced PLD (EPLD)
superPAL
megaPAL
20

Structure of a CPLD: A Closer Look
I/O block
I/O block
PAL-like
block
Interconnection wires
PAL-like
block
PAL-like
block
PAL-like
block
I/O block
I/O block
21

Section of a CPLD
22

CPLD Size Comparison
A CPLD is just a collection of individual PLDs on a single
chip
accompanied by a programmable interconnection structure that allows
the PLDs to be hooked up to each other on-chip
in the same way that a clever designer might do with discrete PLDs
off-chip
For an SPLD, the chip area for n times as much logic is close
to n 2 … (think about an n x n square)
For a CPLD, the chip area for n times as much logic is only n
times the area of a single PLD plus the area of the
programmable interconnect structure.
23

CPLDs
Rising densities/performance and declining prices
become a good choice for many applications
100K gates today
250K+ gates in near future
Low-density Low density CPLD (32 macrocells/44 pins)
5ns logic delays
High-density High density CPLD (128 macrocells/100 pins)
7.5ns logic delays
24

CPLD Components
Primitive or basic cells
The term “primitive primitive” usually refers to simple logic cells
such as NAND, NOR, FLIP-FLOPs
FLIP FLOPs, , LATCHES,
BUFFERS, and INVERTERS
Macrocells
also called 'megacells 'megacells'
' or 'supercells 'supercells'
'
offer diversified functions
range from a shift register to a complex microprocessor
25

Types of Macrocells
There are two types of macrocells
Hard (Hardware)
Soft (VHDL library)
Soft macrocells are functions comprised of primitive
cells, which are placed and routed along with the
rest of the chip.
No cell layouts exist for the soft macrocells. macrocells
Designers can configure soft macrocells at the time
of instantiation.
26

Hard Macrocells
Hard macrocells implement functions using custom
design, usually to achieve better performance and
transistor densities.
The vendor tests and verifies both the hard
macrocell layout and its function.
Standard cells usually use hard macrocells but in
some special cases gate arrays may also use them.
A hard macrocell provides speed improvement over
a functionally equivalent soft macrocell. macrocell.
Thus the
hard macrocell occupies less area.
27

Who makes the CPLDs? CPLDs
Manufacturer CPLD Products URL
Altera MAX 5000, 7000 & 9000 www.altera.com
Altmel ATF & ATV www.atmel.com
Cypress FLASH370, Ultra37000 www.cypress.com
Lattice ispLSI 1000 to 8000 www.latticesemi.com
Philips XPLA www.philips.com
Vantis MACH 1 to 5 www.vantis.com
Xilinx XC9500 www.xilinx.com
Lect #14 Rissacher EE365
28

Altera
Product
MAX5000, MAX7000, MAX9000
MAX7000S: In-circuit programmability
Feature
Logic Array Block (LAB)
Programmable Interconnect Array (PIA)
Variable sized OR gate
29

Altera
Altera MAX 7000 Series
(Programmable Interconnect Matrix)
(Logic Array Block)
30

Altera
Altera MAX 7000 Logic Array Block (LAB)
31

Altera
MAX 7000 Macrocell
32

Altera Macrocell
Interconnect
To Other
Macrocells
Invert
Control
Mux
Global
Clock
D Q
Memory
Clock
Control
Mux
Output
Control
Altera Macrocell
Pad
33

Altera
Product
FLASHlogic
Collection of Configurable Function Blocks (CFB).
Feature
On-chip SRAM blocks
In-system programmability
34

Altera
Altera FLASHlogic CPLD
35

AMD
Product
Mach1, Mach2: 22V16 PALs
Mach3, Mach4: 34V16 PALs
Mach5: 34V16 PALs and enhanced speed
Feature
Product term allocation for variable sized OR gate
Output switch matrix for driving any of the I/O pins
connected to the PAL block
36

AMD
Structure of AMD Mach 4 CPLD
37

AMD
AMD Mach 4 PAL-like(34V16) Block
38

Lattice
Product
pLSI, ispLSI
isp = in-system programmability
3000,4000,5000 series
Feature
Generic Logic Block (GLB)
Global Routing Pool (GRP)
39

Lattice
Lattice pLSI Architecture
40

Cypress
Product
FLASH370
Feature
Generic Logic Block (GLB)
Programmable Interconnect Matrix (PIM)
relatively more I/Os
# of macrocells = # of bi-directional I/O pins
41

Cypress
Architecture of Cypress FLASH370 CPLDs
42

Xilinx
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
43

Xilinx: Xilinx:
XC9500 Device Family
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.
44

Xilinx
Architecture of Xilinx 9500 CPLDs
45

Xilinx: Xilinx:
XC9500 Device Family
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.
46

Xilinx: Xilinx:
XC9500 Device Family
47

Xilinx: Xilinx:
XC9500 Device Family
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.
48

Xilinx: Xilinx:
XC9500 Device Family
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.
49

Xilinx: Xilinx:
XC9500 Device Family
Each XC9500 macrocell may be individually configured for a
combinatorial or registered function. The macrocell and
associated FB logic is shown in Figure 3.
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).
50

Xilinx: Xilinx:
XC9500 Device Family
51

Xilinx: Xilinx:
XC9500 Device Family
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.
52

Xilinx: Xilinx:
XC9500 Device Family
The FastCONNECT switch matrix connects signals to the FB
inputs, as shown in Figure 9. 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.
53

Xilinx: Xilinx:
XC9500 Device Family
54

Xilinx: Xilinx:
XC9500 Device Family
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.
55

Xilinx: Xilinx:
XC9500 Device Family
56

Xilinx: Xilinx:
XC9500 Device Family
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.
57

Xilinx: Xilinx:
XC9500 Device Family
XC9500 devices can also be programmed by the
XilinxHW130 device programmer as well as thirdparty
programmers. This provides the added
flexibility of using pre-programmed devices during
manufacturing, with an in-system programmable
option for future enhancements.
58

Xilinx: Xilinx:
XC9500 Device Family
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 writeprotection
may be deactivated when the device needs to be
reprogrammed with a valid pattern.
59

Xilinx: Xilinx:
XC9500 Device Family
60

Xilinx: Xilinx:
XC9500 Device Family
Basic Timing Model
61