Digital Systems

1
Digital Systems

• CPLD FPGA

2
Problems Using SPLD

• Current trend is
• Increasing gate count
• Increase design complexity
• Requirement for smaller size due to lower cost,
  lower power and higher reliability
• Fast prototyping for quick design verification
• PROM, PLA and PAL not used much except in small
  designs!
• Solution
• CPLD for intermediate complexity
• FPGA for very complex designs (up to millions of
  gates)

3
FPGA AND CPLD

• FPGA - Field-Programmable Gate Array.
• CPLD - Complex Programmable Logic Device
• FPGA and CPLD is an advance PLD.
• Support thousands of gate where as PLD only
  support hundreds of gates.

4
Advantages of CPLDs

• Reduced circuit board space utilization, and
  significant cost savings
• A 44-pin CPLD is
• equivalent to 600 gates
• Some CPLDs have gate equivalents
• in the millions and over 1000 pins.
• Universal inventory, as one IC can be programmed
  for various applications

5
Advantages of CPLDs

• Reprogrammability
• CPLD can be reprogrammed hundreds of times.
• Number of I/Os
• CPLDs have large amounts of programmable
  input/output contacts.

6
Advantages of CPLDs

• Easiest to modify
• Modify the software to modify the hardware
• Easy to duplicate
• Direct entry of conceptual design into functional
  circuit
• Streamlined design to prototype process

7
Advantages of CPLDs

• Software and Language
• Manufacturers of CPLDs supply design software
  (basic software, like the Max PlusII , is a free
  download)
• VHDL is a standards-based language that most
  manufacturers conform to.
• Simple Interface
• Devices can be interfaced directly to a computer
  with a serial or USB connection .
• In-circuit modifications
• With the proper interface connections, the CPLD
  logic can be edited in-circuit.
• Transportable design
• As a designer you may easily exchange your
  designs and design modifications (email, CD, web
  site, etc etc).

8
CPLD

• Complexity of CPLD is between FPGA and PLD.
• CPLD featured in common PLD-
• Non-volatile configuration memory does not need
  an external configuration PROM.
• Routing constraints. Not for large and deeply
  layered logic.

9
CPLD

• CPLD featured in common FPGA-
• Large number of gates available.
• Can include complicated feedback path.
• CPLD application-
• Address coding
• High performance control logic
• Complex finite state machines

10
CPLD

• CPLD architecture-

LAB Logic Array Block / uses PALs PIA
Programmable Interconnect Array
11
CPLDs and FPGAs
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CPLDs vs. FPGAs

• CPLD architecture
• Small number of largish PLDs (e.g., 36V18 6V18)
  
• on a single chip
• Programmable interconnect between PLDs

13
FPGA

• FPGA applications-
• DSP
• Software-defined radio
• Aerospace
• Defense system
• ASIC Prototyping
• Medical Imaging
• Computer vision
• Speech Recognition
• Cryptography
• Bioinformatic
• And others.

14
FPGA

• FPGA architecture-