CPLD 1.1

©Paul R. Godin

Last Mod: Dec 2013

prgodin @ gmail.com

CPLD 1.2

CPLDs

Complex Programmable Logic Devices (CPLDs) are digital devices that can be programmed with digital logic functions.

The functions are designed using a software application and uploaded to the chip.

CPLD 1.3

CPLDs The programmed logic functions may be

relatively simple or complex.

Many aspects of the VHDL programming language resembles other programming languages.

The graphic editors resemble Electronics WorkBench / MultiSIM.

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Programmable Logic First introduced in the 70’s, programmable devices fall

into several families of devices: PLA (Programmable Logic Array) PAL (Programmable Array Logic) GAL (Generic Array Logic) SPLD (Simple Programmable Logic Device) CPLD (Complex Programmable Logic Device) popular FPGA (Field-Programmable Gate Arrays) very popular

Embedded systems are another group of programmable devices but include more complex elements such as a microprocessor. Examples include microcontrollers and complete systems such as portable telephones, music players, vehicle computers, etc. Semester 3 and 4 will address embedded systems.

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Terminology

Many earlier devices were OTP (One-Time Programmable). The PAL (Programmable Array Logic) is this type of device.

Today, most of the CPLDs (Complex Programmable Logic Devices) and FPGAs (Field-Programmable Gate Arrays) are re-programmable.

CPLD 1.6

CPLD 1.7

Reduced circuit board space utilization, and significant cost savings

A low-end 44-pin CPLD is equivalent to 600 gates

Some CPLDs have gate equivalents in the millions and over 324 pins

Advantage #1:

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Advantage #2:

Easiest to modify a circuit’s functionsModify the software to modify the hardware

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Advantage #3:

Direct entry of conceptual design into a functional circuit

Streamlined design to prototype process

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Advantage #4: Transportable design

As a designer you may easily exchange your designs and design modifications (email, CD, web site, etc…). People separated by distance may work together on the same design.

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Advantage #5 and #6:

Universal inventory, as one IC can be programmed for various applications

Easy to duplicate

Design

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Re-programmabilityCPLD can be reprogrammed hundreds of times.

Advantage #7:

Design 1

Design 2

Design 3

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Software and Language

Manufacturers of CPLDs supply design software (basic software is often offered as a free download for students)

VHDL is a standards-based language that most manufacturers conform to (although there are 2 standards).

Advantage #8:

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Advantage #9 and #10:

Simple InterfaceDevices can be interfaced directly to a computer

with a serial, parallel or USB connection.

In-circuit modificationsWith the proper interface connections, the CPLD

logic can be edited (reprogrammed) in-circuit.

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Advantage #11:

Package options Number of I/Os: CPLDs can have large amounts of

programmable input/output contacts. Capacity: CPLDs can be selected based on programming

capacity.

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CPLD 1.17

Basic Architecture

Y=ABC+ABC+ABC

•CPLDs are comprised of SPLDs.

•SPLDs are an SOP-style of programmable devices

•SOP (Sum Of Products) takes the form

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Basic Architecture

Programmable Sum-Of-ProductsHas basic make/break connection logic

Each intersect is either connected or disconnected to make up the SOP connections.

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Basic Architecture

Example of an SOP connection:

What is the Boolean Expression for this circuit? (go back 2 slides)

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Programmability

The devices vary by their complexity and their programmability/re-programmability.

The node connections are make internally during the programming process.

Basic Architecture

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Basic Architecture (SPLD)

In

In

In

In

AND Array OR Array

Out

Out

Out

Out

Depending on the device, the above blocks may be fixed, programmable or re-programmable.

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The CPLD The Complex Programmable Logic Device

(CPLD) consists of arrays of Simple Programmable Logic Devices.

These SPLD are interconnected with a Programmable Interface Array (PIA).

Additional elements in a CPLD include flip-flops and directional control.

CPLD 1.23

Basic Architecture (CPLD)

PIA

(Pro

gram

mab

le Interco

nn

ect Array)

LAB(Logic Array Block)

LAB(Logic Array Block)

LAB(Logic Array Block)

LAB(Logic Array Block)

I/O

I/O

I/O

I/O

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Manufacturers CPLDs are manufactured by several companies including:

Altera Atmel Cypress Texas Instruments Xilinx

All utilize similar internal configurations but require proprietary software to compile and update the devices.

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Altera

Altera (www.altera.com) is one of the leaders in the CPLD marketplace.

Altera offers a great range of CPLDs, FPGAs and other programmable devices.

Products range from the MAX series (basic CPLD) to newer products that contain embedded microprocessors.

CPLD 1.26

End of CPLD Intro

©Paul R. Godinprgodin @ gmail.com 7H