Farnell | Electronic Component Distributors · 2009. 2. 27. · Information About Cautions and Warnings iii Preface About This Manual This users guide describes the function and operation

April 2002 Data Acquisition Products

User’s Guide

SLAU083

IMPORTANT NOTICE

Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications,enhancements, improvements, and other changes to its products and services at any time and to discontinueany product or service without notice. Customers should obtain the latest relevant information before placingorders and should verify that such information is current and complete. All products are sold subject to TI’s termsand conditions of sale supplied at the time of order acknowledgment.

TI warrants performance of its hardware products to the specifications applicable at the time of sale inaccordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TIdeems necessary to support this warranty. Except where mandated by government requirements, testing of allparameters of each product is not necessarily performed.

TI assumes no liability for applications assistance or customer product design. Customers are responsible fortheir products and applications using TI components. To minimize the risks associated with customer productsand applications, customers should provide adequate design and operating safeguards.

TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right,copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or processin which TI products or services are used. Information published by TI regarding third–party products or servicesdoes not constitute a license from TI to use such products or services or a warranty or endorsement thereof.Use of such information may require a license from a third party under the patents or other intellectual propertyof the third party, or a license from TI under the patents or other intellectual property of TI.

Reproduction of information in TI data books or data sheets is permissible only if reproduction is withoutalteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproductionof this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable forsuch altered documentation.

Resale of TI products or services with statements different from or beyond the parameters stated by TI for thatproduct or service voids all express and any implied warranties for the associated TI product or service andis an unfair and deceptive business practice. TI is not responsible or liable for any such statements.

Mailing Address:

Texas InstrumentsPost Office Box 655303Dallas, Texas 75265

Copyright 2002, Texas Instruments Incorporated

EVM IMPORTANT NOTICE

Texas Instruments (TI) provides the enclosed product(s) under the following conditions:

This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATIONPURPOSES ONLY and is not considered by TI to be fit for commercial use. As such, the goods being providedmay not be complete in terms of required design-, marketing-, and/or manufacturing-related protectiveconsiderations, including product safety measures typically found in the end product incorporating the goods.As a prototype, this product does not fall within the scope of the European Union directive on electromagneticcompatibility and therefore may not meet the technical requirements of the directive.

Should this evaluation kit not meet the specifications indicated in the EVM User’s Guide, the kit may be returnedwithin 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVEWARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED,IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANYPARTICULAR PURPOSE.

The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the userindemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the productsreceived may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). Due to the open constructionof the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostaticdischarge.

EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLETO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.

TI currently deals with a variety of customers for products, and therefore our arrangement with the user is notexclusive.

TI assumes no liability for applications assistance, customer product design, software performance, orinfringement of patents or services described herein.

Please read the EVM User’s Guide and, specifically, the EVM Warnings and Restrictions notice in the EVMUser’s Guide prior to handling the product. This notice contains important safety information about temperaturesand voltages. For further safety concerns, please contact the TI application engineer.

Persons handling the product must have electronics training and observe good laboratory practice standards.

No license is granted under any patent right or other intellectual property right of TI covering or relating to anymachine, process, or combination in which such TI products or services might be or are used.

Mailing Address:



EVM WARNINGS AND RESTRICTIONS

It is important to operate this EVM within the power supply voltage range of 5.5 V to 15 V (5 V for regulated power inputs) and the analog input range of 0 V to 5 V.

Exceeding the specified supply range may cause unexpected operation and/or irreversibledamage to the EVM. If there are questions concerning the supply range, please contact a TIfield representative prior to connecting the input power.

Applying loads outside of the specified output range may result in unintended operation and/orpossible permanent damage to the EVM. Please consult the EVM User’s Guide prior toconnecting any load to the EVM output. If there is uncertainty as to the load specification,please contact a TI field representative.

During normal operation, some circuit components may have case temperatures greater than40°C. The EVM is designed to operate properly with certain components above 40°C as longas the input and output ranges are maintained. These components include but are not limitedto linear regulators, switching transistors, pass transistors, and current sense resistors. Thesetypes of devices can be identified using the EVM schematic located in the EVM User’s Guide.When placing measurement probes near these devices during operation, please be awarethat these devices may be very warm to the touch.

Mailing Address:



Information About Cautions and Warnings

iii

Preface

About This Manual

This users guide describes the function and operation of the ADS1254EVManalog-to-digital converter evaluation module. This manual helps you quicklyset up the evaluation module and its accompanying software, so that you canrapidly test and evaluate the ADS1254. Complete circuit descriptions, as wellas schematic diagrams, PCB layouts, and bill of materials, are also included.

How to Use This Manual

This manual begins with an introductory chapter which describes the EVM andwhat it can do. If you are anxious to set things up and start testing, we suggestyou read at least the first two chapters. These two chapters introduce you tothe board and how to set it up to start working with it.

Information About Cautions and Warnings

This book may contain cautions and warnings.

This is an example of a caution statement.

A caution statement describes a situation that could potentiallydamage your software or equipment.

This is an example of a warning statement.

A warning statement describes a situation that could potentiallycause harm to you.

The information in a caution or a warning is provided for your protection.Please read each caution and warning carefully.

Trademarks

iv

Related Documentation From Texas Instruments

Data Sheets Literature Number

ADS1254 SBAS213MAX3238 SLLS349MSP430F149 SLAS272REG1117 SBVS001REG103 SBVS010OPA350 SBOS099SN74LVC1G07 SCES296SN74LVC1G08 SCES217SN74LVC1G125 SCES223

FCC Warning

This equipment is intended for use in a laboratory test environment only. It gen-erates, uses, and can radiate radio frequency energy and has not been testedfor compliance with the limits of computing devices pursuant to subpart J ofpart 15 of FCC rules, which are designed to provide reasonable protectionagainst radio frequency interference. Operation of this equipment in other en-vironments may cause interference with radio communications, in which casethe user at his own expense will be required to take whatever measures maybe required to correct this interference.

Trademarks

Windows is a trademark of Microsoft Corporation.

If You Need Assistance. . .

If you have questions about this or other Texas Instruments data converterevaluation modules, feel free to e–mail the data converter application team [email protected]. Include the product name in the subject heading.

Contents

v

1 Introduction 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 The ADS1254 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 EVM System Overview 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Analog Inputs 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Prototyping Area 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 Power Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 Host Computer Requirements 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 Getting Started 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Unpacking the EVM 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Default Configuration 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Quick Start 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 Operation 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Jumpers 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.1.1 JMP1: Reference Source Select 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.2 JMP2, JMP3: Power Source Select 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.3 JMP4: Reference Disconnect 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.4 JMP5: MCU Disable 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2 Reset Switch 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Connectors 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.3.1 J7: RS-232 Connector 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.2 J6: 3.3-V JTAG Port 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.3 J1, J4, J5, BT1: Power Connectors 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.4 J2: Analog Inputs 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.5 J3: External Reference Input 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.6 J8: External Digital Control 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.7 J9, J10: DSK Motherboard Connectors 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.8 TP1–6: Test Point 3-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.4 Circuit Description 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.1 ADS1254 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.2 Microcontroller 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.3 Clock Generation 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.4 Firmware and Host Communication 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.5 Power Supply 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.5 Host PC Software 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.1 Main Window 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.2 Display Modes 3-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.3 Setup Dialog 3-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents

vi

4 Physical Description 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Board Layouts 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Schematics 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figures

1–1 ADS1254EVM Block Diagram 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–2 ADS1254EVM Component Locations 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1 Start-Up Display 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–1 Main Window 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3–2 Setup Dialog 3-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4–1 Board Layout Top Layer 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–2 Board Layout Bottom Layer 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–3 Schematic (Sheet 1 of 2) 4-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–4 Schematic (Sheet 2 of 2) 4-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Tables

2–1 Factory Jumper Settings 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–1 Jumper/Function Reference 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–2 J7: RS-232 Port Pinout 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–3 J8: 3.3-V JTAG Port 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–4 J1: Unregulated Power Input Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–5 J4: External Digital Power Supply Input Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–6 J5: External Analog Power Supply Input Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–7 BT1: 9-V Battery Connector 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–8 J2: Analog Inputs 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–9 J3: External Reference Input 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–10 J8: 3.3-V JTAG Port 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–11 TP1–6: Test Points 3-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1

This chapter provides an overview of the ADS1254EVM evaluation moduleand software.

Topic Page

1.1 The ADS1254 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2 EVM System Overview 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.3 Analog Inputs 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.4 Prototyping Area 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.5 Power Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.6 Host Computer Requirements 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 1

The ADS1254

1-2

1.1 The ADS1254

The ADS1254 is a precision 24-bit delta-sigma analog-to-digital converter withfour differential input channels. The delta-sigma architecture employed in theADS1254 enables the device to achieve 19 bits of effective resolution (1.8 ppmRMS noise) at data rates of up to 20 kHz. The part also has a no-missing-codescharacteristic across the full 24 bit range.

The ADS1254 employs an unidirectional two-wire synchronous serialinterface (modified SPI) for communication with the host system. Isolation canbe applied to this interface at minimal cost.

1.2 EVM System Overview

A block diagram of the ADS1254 evaluation module is shown in Figure 1–1.

Figure 1–1. ADS1254EVM Block Diagram

RS-232Serial Port

MSP430F149Microcontroller

128 k × 8SRAM

ClockGenerator

ADS1254

ReferenceBuffer

Serial Data

SPI

Inputs

Reference Inputs

SystemClock

During normal operation, data is read from the ADS1254 into the user’scomputer via the ADS1254EVMs RS-232 port. Once read, the data can bedisplayed and analyzed in a variety of ways using the supplied ADS1254EVMsoftware.

The ADS1254 can supply data much faster than it can be transmitted to thehost PC over the RS-232 connection. Because of this, data read from theADS1254 is stored in an onboard RAM, where it is kept until retrieved by thehost system. This process is controlled by the user through the ADS1254EVMsoftware.

Analog Inputs

1-3Introduction

The ADS1254EVM incorporates a PLL-based clock generator which cansynthesize clocks of nearly arbitrary frequency up to the maximum of 8 MHz.The PLL exhibits increased jitter, so for certain clock frequencies, a directdivide-down circuit derived from a crystal oscillator is used instead. Thedivide-down is selected automatically.

The ADS1254EVM can be powered using an ac power adapter (not included),a 9-volt battery, or a user-supplied laboratory power supply.

A photograph of the ADS1254EVM with the locations of major componentshighlighted is shown in Figure 1–2.

Figure 1–2. ADS1254EVM Component Locations

CHANNEL INPUTS

EXTERNALREFERENCE

INPUT

RS-232 PORT

ANALOGREGULATED

POWER

DIGITALREGULATED

POWER

UNREGULATEDPOWER

JTAGADS1254

BATTERYCONNECTOR

MCU DISABLE VREF DISCONNECTVREF SOURCE SELECT

DIGITAL VDD SOURCE

ANALOG VDD SOURCE

SRAM

MCU

DSK PERIPHERAL CONNECTOR

DSK MEMORY CONNECTOR

EXT DIGITAL

1.3 Analog InputsAnalog input is supplied through the eight-way screw terminal block, J2. Eachinput is connected to the ADS1254 through a 1-kΩ resistor. The inputs are notprotected against overvoltage.

1.4 Prototyping AreaA prototyping area is provided on the ADS1254EVM. This may be used toincorporate additional circuitry, such as special reference or conditioningcircuits, into the system. Certain holes are connected to convenient circuitpoints, such as ground, reference, etc.

1.5 Power RequirementsThe ADS1254EVM must be supplied with 5.5 V–15 V for proper operation.Power can be supplied through barrel jack, J1 (tip positive), screw terminalblocks J4 and J5, or with a 9-volt battery connected to battery snap BT1.

Host Computer Requirements

1-4

1.6 Host Computer Requirements

The ADS1254EVM software is designed to run on a PC running anyWindows platform (Windows 95, 98, NT, 2000, etc.).

Minimum Requirements:

IBM-compatible 486 PC or higher

Windows 95/98/2000 or NT4.0

64 MB RAM minimum

20 MB available hard disk space

CD-ROM drive

Available serial port

2-1Getting Started

This chapter guides you through unpacking your EVM and setting it up so youcan begin working with it immediately.

Topic Page

2.1 Unpacking the EVM 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2 Default Configuration 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.3 Quick Start 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 2

Unpacking the EVM

2-2

2.1 Unpacking the EVM

After unpacking the ADS1254EVM kit, check to make sure you received all ofthe items listed here:

ADS1254EVM board

9-pin D-sub male-female serial cable

Software CD-ROM

If any of these items are missing, contact Texas Instruments to receivereplacements.

2.2 Default Configuration

Although much of the ADS1254EVMs operation is controlled by the host PC,some configuration must be done directly on the board, using five jumpers(shorting blocks). The ADS1254EVM is configured as follows at the factory:

Table 2–1.Factory Jumper Settings

Jumper Identifier Description Default Setting

JMP1 External reference select 2–3

JMP2 Digital power supply source 1–2

JMP3 Analog power supply source 1–2

JMP4 Reference disconnect 1–2

JMP5 MCU disable Disconnected

For more information about the jumpers, see Section 3.1.

Quick Start

2-3Getting Started

2.3 Quick Start

Once the ADS1254EVM has been unpacked from its shipping container, andyou have verified that the board is configured as shown in Table 2–1, it can bepowered on and tested.

First, connect the board to the host PC using the supplied 9-pin serial cable.Then power the board on by plugging a wall power adapter into a suitable acpower source and plugging the barrel plug into the barrel jack on theADS1254EVM, or by connecting your laboratory power supply to the externalpower inputs and setting JMP2 and JMP3 to the 2–3 position. (You do not haveto connect the serial cable first; it is also acceptable to apply power to the boardfirst.) When the board is properly powered on, the two power good indicatorlamps near the power connectors glow brightly. (The 5-V LED may glowbrighter than the 3.3-V LED; this is normal.)

Place the CD-ROM into your PCs CD-ROM drive. Locate the setup programon the disk, and run it. The setup program installs the ADS1254EVM softwareon your PC. If you are running a Windows platform that is NT-based, such asWindows NT or Windows 2000, you need administrator privileges to install thesoftware. Follow the instructions that the installer gives you.

Once the program has been successfully installed, it can be executed. Whenthe program is run, it displays a title screen, and then you see something likethe display in Figure 2–1.

Figure 2–1. Start-Up Display

Quick Start

2-4

The setup window appears first, allowing you to make adjustments to theprograms configuration. For the test run, you should select the serial port towhich the ADS1254EVM is connected, using the serial port menu.

If no serial ports are available, a message box appears informing you that theprogram cannot run. This is usually because other programs are using all ofthe available serial ports. If this is the case, closing these programs andrerunning the program should fix the problem.

Once the correct serial port has been selected, click OK. The setup dialogdisappears and you see the main window. Click the acquire button. After aperiod of activity, you see data displayed in the data display window.

3-1Operation

This chapter describes each function of the ADS1254EVM, and how to use theaccompanying software to control the ADS1254.

Topic Page

3.1 Jumpers 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2 Reset Switch 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.3 Connectors 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.4 Circuit Description 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.5 Host PC Software 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 3

Jumpers

3-2

3.1 Jumpers

Table 3–1 shows the function of each jumper on the EVM:

Table 3–1.Jumper/Function Reference

ReferenceDesignator

Setting Function Default Section

JMP1 1 to 2 External reference 2–3 Section 3.1.1

2 to 3 Onboard reference

JMP2 1 to 2 Digital power supplied from barreljack, battery, or DSK

1–2 Section 3.1.2

2 to 3 Digital power supplied from screwterminal block J4

JMP3 1 to 2 Analog power supplied from barreljack, battery, or DSK

1–2 Section 3.1.2

2 to 3 Analog power supplied from screwterminal block J4

JMP4 Connected Reference pin is connected Connected Section 3.1.3

Disconnected Reference pin is not connected

JMP5 Connected MCU controls ADS1254 Disconnected Section 3.1.4

Disconnected MCU does not control ADS1254

3.1.1 JMP1: Reference Source Select

The ADS1254EVM can use an externally supplied reference or an onboard4.096-V zener reference (D1 and R1); use JMP1 to connect the desiredreference source. Shorting pins 1 and 2 connects the external reference;shorting pins 2–3 connects the onboard reference.

3.1.2 JMP2, JMP3: Power Source Select

The ADS1254 has separate analog and digital power supplies. JMP2 is usedto select the source for the digital power supply, and JMP3 is used to selectthe source for the analog supply. To use the barrel jack or battery (onboardregulator), short pins 1–2; if you wish to use an external power supply, shortpins 2–3.

3.1.3 JMP4: Reference Disconnect

JMP4 is used to connect an external reference directly to the ADS1254, with-out using the onboard filtering. Removing this jumper disconnects theADS1254 reference pin. External reference voltage must be applied to pin 2.

Jumpers

3-3Operation

3.1.4 JMP5: MCU Disable

Shorting the pins of this jumper has the same effect as plugging theADS1254EVM into a DSP DSK: the onboard regulators are shut down, and ifpower is still available, the MCU is disabled. Power may still be suppliedthrough the external power connectors J4 and J5, or through the DSK;however, power cannot be supplied to the onboard clock generator from theDSK, since the clock generator is only supplied from the onboard regulators.

If you want to use an external system to control the ADS1254, instead of theonboard MCU, you must connect this jumper to prevent conflicts with the MCU.Since this jumper disables the onboard power supply, you must also power theboard externally.

If JMP5 is shorted, and power is available to the MCU, it is active, but iteffectively disconnects itself from the ADS1254 by 3-stating any pins leadingto the 1254. This prevents conflicts with the DSK. The MCU can stillcommunicate with the host PC in this mode.

Reset Switch

3-4

3.2 Reset Switch

Switch SW1 is a miniature pushbutton which, when pressed, forces the MCUsRESET line low. When released, the MCU enters a reset cycle. Ifcommunication becomes disrupted between the host and the board, or theboard is unresponsive, pressing RESET returns the system to normaloperation.

3.3 Connectors

The various connectors on the ADS1254EVM are described in this section.

3.3.1 J7: RS-232 Connector

The host PC controls the board through this connector, which is a 9-pin femaleD-shell type, pinned out in the usual manner. Certain of the flow control linesare used for special purposes by the ADS1254EVM board; these aredescribed in the table.

In the RS-232 electrical specification, –5 V to –15 V on a line indicates a logichigh (mark), and 5 V to 15 V indicates logic low (space). Line states aredescribed here according to their logical states.

If a non-handshaking RS-232 cable is used, that is, one which connects onlyRD, TD, and signal ground. The board can still operate normally, but it cannotbe reset by the host PC, and bootstrap firmware upgrading cannot beperformed through the serial port (it can still be done through the JTAG portJ6, but this requires a special programming adapter and software).

Table 3–2.J7: RS-232 Port Pinout

PinNumber

SignalName

RS-232 Name Direction(at board)

Function

1 DCD Data carrier detect Output None

2 RD Receive data Output Serial data output to host PC

3 TD Transmit data Input Serial data input from host PC

4 DTR Data terminal ready Input Connected to the MCUs reset circuit. A lowon this line resets the MCU. Must be heldhigh for normal operation

5 SG Signal ground Power Ground reference

6 DSR Data set ready Output None

7 RTS Request to send Input Connected to TCK on MCU. Used for boot-strap firmware loading. Must be held highfor normal operation

8 CTS Clear to send Output None

9 RI Ring indicator Output None

Connectors

3-5Operation

3.3.2 J6: 3.3-V JTAG Port

This connector is used mainly during firmware development. It provides a fastway to download firmware into the MCU, and also allows access to the MCU’shardware debugging features. If you have MSP430 software developmenttools, you can use this port to write your own firmware for the ADS1254EVM.

This port is designed for use only with 3.3-V JTAG tools, such as thoseprovided by TI for use with the MSP430. If you attempt to use 5-V JTAGtools with this port, you permanently damage the MSP430, as it is not 5-Vtolerant.

Table 3–3.J8: 3.3-V JTAG Port

Pin Num-ber

PinSymbol

Signal Name Direction(at board)

Function

1 TDI/TDO Test data in/out Output JTAG TDO port (see JTAG standard)

2 VCCTOOL Power from JTAGadapter

Power JTAG adapter–provided power supply(not used on ADS1254EVM)

3 TDI/VPP Test data in/pro-gramming voltage

Input Used as a test data input, and for blowingthe security fuse

4 VCCLOCAL Power sensefrom board

Output High rail from board; used for signal sensewhen board is using its own power supplyduring programming

5 TMS Test mode select Input JTAG test mode select pin (see JTAGstandard)

6 NC Not connected – Not used

7 TCK Test clock Input JTAG serial clock input (see JTAGstandard)


9 GND Ground Power Signal ground


11 RST/NMI Reset/non-mask-able interrupt

Input MCU reset line




Connectors

3-6

3.3.3 J1, J4, J5, BT1: Power Connectors

The ADS1254EVM features a flexible power supply. Externally generatedpower, the onboard regulator circuitry and an ac adaptor, or a 9-V battery mayall be used to supply power. Furthermore, the separated analog and digitalpower supplies may be powered differently; for example, the analog powersupply may be powered externally, and the digital power supply may use thebuilt-in regulator, at the same time. (This is configured using jumpers JMP2and JMP3.) The exception to this is that the battery and ac adaptor cannot beused at the same time (see below).

An additional source of power may come from a DSP development board(DSK). When the ADS1254EVM is plugged in to a DSK motherboard, theonboard regulators are shut down, and power is sourced from the DSK. TheDSK’s power supply, however, may not be suitable for powering the analogcircuitry, as it is likely to be somewhat dirty, so for best performance it isnecessary to use an external supply for the analog circuitry when using theADS1254EVM with a DSK.

Four power connectors are provided: screw terminal blocks J4 and J5 forexternal power, battery terminal BT1 for a 9-V transistor radio battery, and J1for a wall-wart. J1 is a switched jack: connecting a plug to J1 automaticallydisconnects the battery terminal. This prevents the battery and J1 fromsupplying power simultaneously.

Battery power is regulated by the same circuitry that regulates J1 (wall-wart)power.

Be very careful when connecting external power supplies to J4 and J5.They are not protected against reversed polarity. If you connect thembackwards (that is, with reversed polarity), permanent damage to theADS1254EVM is likely.

Table 3–4.J1: Unregulated Power Input Connector

Terminal Name Function

Tip Positive power supply input

Sleeve Power ground

Table 3–5.J4: External Digital Power Supply Input Connector

Terminal Number Function

1 Digital positive power supply input

2 Digital ground

Table 3–6.J5: External Analog Power Supply Input Connector


1 Analog positive power supply input

2 Analog ground

Connectors

3-7Operation

Table 3–7.BT1: 9-V Battery Connector

Terminal Name Function

Split (female) ring Positive (mates with solid/male post onbattery)

Solid (male) ring Negative (mates with split/female post onbattery)

3.3.4 J2: Analog Inputs

Terminal block J2 is the main analog input to the ADS1254EVM. Two terminalsare provided for each of the ADS1254 four differential inputs. Each terminalis connected to the ADS1254 through a 1-kΩ resistor.

Table 3–8.J2: Analog Inputs

TerminalNumber

TerminalName

ADS1254Pin

Function

1 CH4– 19 Channel 4 negative input

2 CH4+ 20 Channel 4 positive input







3.3.5 J3: External Reference Input

The ADS1254EVM has an onboard 4.096-V bandgap reference. If alower-noise reference source or a reference with a different voltage is desired,it can be connected to screw–terminal block J3. The reference source,onboard or external, is selected using JMP3. Both the onboard and externalreference inputs are filtered and buffered by R2, C3, and U4, and bypassedby C10.

It is also possible to supply a reference voltage directly to the ADS1254 by dis-connecting JMP4 and connecting the reference to pin 2.

Table 3–9.J3: External Reference Input


1 External reference voltage input

2 Analog ground

Connectors

3-8

3.3.6 J8: External Digital Control

Header J8 provides access to certain signals connected between the DSK andthe ADS1254. It can also be used as an additional place to connect externalequipment for communicating with the ADS1254.

Table 3–10.J8: 3.3-V JTAG Port

PinNumber

PinSymbol

SignalName

Direction(at board)

Function

1 NC – – Not connected

3 HOST_CLKXA SERIAL_CLK Input SPI clock for ADS1254

5 HOST_CLKRA HOST_CLKRA Output SPI clock from board; not used

7 HOST_DXA HOST_DXA Output SPI data from board; not used

9 HOST_DRA HOST_DRA Input SPI data for ADS1254 from DSK

11 HOST_FSXA HOST_FSXA Output Frame sync from board; not used

13 HOST_FSRA HOST_FSRA Input Frame sync from DSK; not used

15 HOST_CLKOUT HOST_CLKOUT – Not used

17 HOST_CLKSA HOST_CLKSA – Not used

19 NC – – Not connected

Even-numberedpins

DGND DGND Power Signal ground

3.3.7 J9, J10: DSK Motherboard Connectors

These two connectors are used as both electrical connection and mechanicalsupport for plugging the ADS1254EVM into a DSP DSK. Communicationbetween a DSP on a DSK and the ADS1254 on the EVM is accomplishedthrough these connectors.

J9, the memory interface connector, carries the DSP external bus. J10, theperipheral and control connector, carries various GPIO and peripheral signalsfrom the DSP.

The ADS1254, being a purely SPI part, does not make use of the DSP externalparallel bus; therefore, only one signal connection from J9, a timer output, isused.

J10 carries the DSK serial channels. Texas Instruments DSPs currentlyavailable on DSKs incorporate a multichannel buffered serial port, or McBSP,which among other things supports full-duplex SPI and a frame-sync signal.The ADS1254 has neither of these, so only the McBSPs SPI clock and dataoutputs are connected. The other McBSP signals are brought to J8 forconvenience.

Connectors

3-9Operation

3.3.8 TP1–6: Test Point

The test points are used to monitor certain signals on the board, or to connectexternal signals to the ADS1254.

Consult the ADS1254 data sheet for information on the signals connecteddirectly to the ADS1254.

Table 3–11. TP1–6: Test Points

Test PointDesignator

ADS1254 PinNumber

ADS1254 PinName

Signal Description

TP1 – – Onboard reference voltage

TP2 15 CHS1 Channel Select 1

TP3 16 CHS0 Channel Select 0

TP4 8 ADCLK ADS1254 timing and conversion clock

TP5 13 DOUT SPI data from MCU

TP6 14 SCLK SPI clock

Circuit Description

3-10

3.4 Circuit Description

The ADS1254EVM combines a microcontroller, RAM, and an ADS1254 toprovide a platform for simplified evaluation of the ADS1254.

3.4.1 ADS1254

The ADS1254 (U5) is supported by reference circuitry D1, U4 and associatedcomponents; inputs come from J2 through current–limiting resistors R5–R12.The clock generation circuitry is described below.

For detailed information about the ADS1254, consult the ADS1254 productdata sheet.

3.4.2 Microcontroller

A Texas Instruments MSP430F149 microcontroller (U7), clocked at 8 MHz,provides intelligence for the system. It communicates with the ADS1254 usingone of its two built-in USARTs in synchronous mode, and with the host PCusing the other USART in asynchronous mode. Firmware is stored in andexecuted from the onboard flash memory.

Bulk storage of datapoints collected from the ADS1254 is provided by a128-kilobyte static RAM (U10). It is connected to the MSP430 using 28 GPIOlines.

For detailed information about the MSP430F149, consult the relevantdocumentation, which is available from Texas Instruments website.

3.4.3 Clock Generation

The ADS1254 requires a system clock, from which it derives its sampling rate;the sampling rate is the system clock frequency divided by 384. The systemclock’s maximum specified rate is 8 MHz (maximum sampling frequency is20833 Hz); up to this maximum, virtually any sampling frequency may beselected by generating a clock of the appropriate frequency.

To support a wide range of evaluation situations, the ADS1254EVM has avariable-frequency clock generation system consisting of the MCU, PLL clockgenerator U13, and gate U14. The ICD2053 is a programmable frequencygenerator containing a PLL oscillator and programmable dividers; it is capableof generating frequencies in the 500 kHz–8 MHz range. The reference clockfor the ICD2053 is a buffered version of the MCU main clock, which runs at8 MHz.

Although the ICD2053 adds great flexibility to the ADS1254EVM, its jitter israther high, degrading performance somewhat. The MCU clock source ismuch cleaner. Therefore, those frequencies which can be produced using theMCU are sourced from the MCU instead of the ICD2053. This includes 8 MHz,4 MHz, 2 MHz, and 1 MHz. The choice between the PLL clock and the MCUclock is made by the firmware.

Circuit Description

3-11Operation

3.4.4 Firmware and Host Communication

The ADS1254EVM firmware controls the acquisition of data from theADS1254 and the clock generation circuitry. It is capable of receiving data fromthe ADS1254 at the full data rate, while simultaneously performing averaging.

Communication with the host is performed using TI’s CSR-232 protocol, whichis designed for efficient system control over point-to-point serial links.CSR-232 is based on IEEE P1212r, the control and status registers draftstandard.

The firmware may be upgraded by the user through the serial port. TI mayperiodically make enhancements to the ADS1254EVM firmware; theseupgrades are available on TI’s web site, together with a program for performingthe upgrades.

3.4.5 Power Supply

Power is brought into the board through external power connectors J4 and J5,battery connector BT1, unregulated power input J1, or through the DSKconnectors J9 and J10. If a wall power adaptor is plugged into J1, the batteryis disconnected.

Power supplied from the battery or through J1 is regulated by voltageregulators U1, U12, and U2, which provide 5-V digital and analog supplies, anda 3.3-V digital supply. Power supplied from the external connectors is notfiltered; regulated power of the correct voltages must be supplied to theseconnectors. Power from the DSK is filtered and bypassed. Resistors R15 andR16 limit current in case a DSK is plugged in and the onboard regulators havenot yet shut down.

The board is laid out with separate analog and digital power supplies. Analogpower is 5 V and is supplied from regulator U2, external power connector J5,or the DSK. 3.3-V digital power is supplied from regulator U12 or the DSK.When the external power connector J4 is used, it supplies regulator U12.

Only one component on the board, clock generator U13, uses 5-V digitalpower. When the DSK is used, this component does not operate; however, thisis of no concern, as the DSK supplies its own clock.

Host PC Software

3-12

3.5 Host PC Software

After having installed the software for the ADS1254EVM as described inSection 2.3, you can use it to evaluate the ADS1254. The software is describedin the following subsections.

3.5.1 Main Window

The main window is shown in Figure 3–1. The window is shown as it firstcomes up when the program is started.

Figure 3–1. Main Window

3.5.1.1 Performing an Acquisition

Clicking the acquire button causes an acquisition to begin. Acquisition isperformed in the following sequence:

1) The software configures the ADS1254EVM, telling it what sampling rateto use, how many averages to perform per sample (this is configured inthe Setup window), and how many samples to take.

2) The software instructs the ADS1254EVM to begin sampling.

Host PC Software

3-13Operation

3) The ADS1254EVM begins collecting samples. The ADS1254EVMinforms the software of the progress of the acquisition approximately fourtimes a second; this information is displayed in the status bar at the bottomof the window.

4) The ADS1254EVM tells the software that the acquisition has completed.

5) The software begins reading sample data from the ADS1254EVM. Theread can take some time; the progress of the read operation is indicatedin the status bar.

6) When all of the requested sample data has been read, it is displayed.

3.5.1.2 Acquisition Modes

Two modes of acquisition are available: single shot, and continuous. Themodes are selected using the acquisition mode radio buttons.

In single shot acquisition mode, the program requests one conversion eachtime the acquire button is clicked. In continuous acquisition mode, the programautomatically initiates another conversion when a conversion completes; thisprocess continues until the STOP button is clicked. The STOP button appearswhen an acquisition is started in continuous mode.

3.5.1.3 Sampling Rate

To change the sampling rate, type the desired sampling frequency in hertz inthe sample data rate edit box, and press enter. The program immediatelyrequests that the board change to this sampling rate.

Not all sampling rates are realizable by the board; that is, the clock generatorcircuitry has a finite resolution. The board configures the clock generator sothat it generates the nearest frequency to that requested. It then reports backthe frequency actually being generated. The program replaces the typed-infrequency with the actual frequency being generated by the board, so that youcan always see what the actual sampling frequency is.

Note that the actual frequency of the clock generator is the sampling frequencytimes 384. This adjustment is made by the board.

3.5.1.4 Number of Samples to Acquire

When an acquisition begins, the program requests that the board acquire acertain number of samples. The number of samples to acquire is set using thenumber of samples box. You can type a value in or use the up and downbuttons to select the number of samples to acquire.

Host PC Software

3-14

3.5.2 Display Modes

The evaluation software offers four ways to display sample data:

Scope displays the data as a sample number versus amplitude graph,similar to an oscilloscope

FFT displays a fast Fourier transform of the data on a frequency versusmagnitude graph

Histogram displays the data on a value versus count graph (histogram)

Data list displays the raw sample data in a list

Modes are selected by clicking a tab on the tab bar above the data displayarea, or by selecting an option from the View menu.

The modes are fully described in the following sections.

3.5.2.1 Scope

In scope mode, collected data are displayed as a function of sample number,with the vertical axis measured by code.

You can zoom in on the graph by selecting a rectangular area with the mouse,by clicking and dragging. To zoom out, left-click on the graph and select undozoom from the popup menu that appears; the graph will return to its originalscale.

Left-clicking on the graph brings up a pop–up menu containing numerousdisplay options. Double-clicking with the right mouse button brings up anoptions dialog containing other display options. You can export the graph invarious file formats by selecting export dialog from the popup menu.

3.5.2.2 FFT

In FFT mode, a fast discrete Fourier transform is applied to the dataset, anddisplayed as a graph of frequency in hertz versus magnitude in dB of full scale.A number of options for changing certain parameters of the FFT, such aswindow type and normalization type, are available by clicking the options tab.

You can zoom in on the graph by selecting a rectangular area with the mouse,by clicking and dragging. To zoom out, left-click on the graph and select undozoom from the popup menu that appears; the graph returns to its original scale.

Left-clicking on the graph brings up a popup menu containing numerousdisplay options. Double-clicking with the right mouse button brings up anoptions dialog containing other display options. You can export the graph invarious file formats by selecting export dialog from the popup menu.

Host PC Software

3-15Operation

3.5.2.3 Histogram

In histogram mode, the data are analyzed to see how many times each valueoccurs; this information is shown on a count-versus-value bar graph. Forexample, if the column marked zero shows a bar which is 2 units high, it meansthat two zeros are present in the data. Histograms are useful for analyzingreadings of dc voltages for accuracy.

You can zoom in on the graph by selecting a rectangular area with the mouse,by clicking and dragging. To zoom out, left-click on the graph and select undozoom from the popup menu that appears; the graph returns to its original scale.

Left-clicking on the graph brings up a popup menu containing numerousdisplay options. Double-clicking with the right mouse button brings up anoptions dialog containing other display options. You can export the graph invarious file formats by selecting export dialog from the popup menu.

3.5.2.4 Data List

In data list mode, the data are shown in a list, in order of reception. The datamay be shown in one of four modes:

As integers: Each sample is displayed as a signed base-10 integer. Thesample values are shown exactly as received from the ADS1254.

As hexadecimal integers: Each sample is displayed as an unsignedhexadecimal number. The hexadecimal values are precisely those codesread out from the ADS1254.

As percentage of full scale: The percentage of full scale of each sampleis calculated and displayed.

Scaled by LSB: The voltage measured at each point is calculated anddisplayed.

3.5.3 Setup Dialog

The setup dialog allows you to configure several aspects of the ADS1254EVMsoftware’s operation. It is shown when the program is started, and when theEVM setup option is selected from the edit menu.

Once you are finished making changes in the setup dialog, click the OK buttonto make them effective, or cancel to discard the changes. No changes youmake in the setup dialog take effect before you click the OK button.

Host PC Software

3-16

Figure 3–2. Setup Dialog

3.5.3.1 Serial Port Menu

The serial port menu allows you to choose which serial port to use forcommunication with the ADS1254EVM. The ADS1254EVM must beconnected to the port selected here, or the program will not work.

All of the available ports are shown in the menu. If you know that a port exists,but you do not see it in the menu, it usually means that the port is being usedby another program.

3.5.3.2 Channel to Acquire

The ADS1254EVM can read any of four differential channels. Use the channelto acquire buttons to select which channel to read when performing anacquisition.

By default, this is set to CH1 (channel 1).

3.5.3.3 Reference Voltage

Here you can tell the program what reference voltage you are using. This valueis used in certain display calculations. You must input the correct referencevoltage here, because the board cannot detect the reference voltage, so thesoftware has no way to obtain the information automatically.

Changing the reference voltage here does not affect the operation of theboard; it only changes the reference voltage value used by the program incertain calculations. If the reference voltage selected here is incorrect, somevalues shown by the program will be incorrect, but the program and boardoperate normally otherwise.

Host PC Software

3-17Operation

3.5.3.4 Averaging

The ADS1254EVM board can average together a selectable number ofsamples for each reading. If you want to perform averaging on the data, thiscan drastically reduce the download time, since averaging is performed on theboard, and only the averaged data is downloaded by the host. It also allowsmuch longer readings to be taken, since the board’s RAM is not filled up bysamples which are averaged together; instead, averaging is done before thedata is written into the board’s RAM.

The figure selected here is the number of successive samples that arecollected together and averaged to form one sample. For example, if youselect 32 here, then for each reading, 32 samples are taken and averagedtogether to form that reading. This means that if you request 256 samples tobe acquired, 256 samples are returned, but each sample returned is actually32 successive samples averaged together; so for that acquisition, 8,192samples are taken by the ADS1254.

Note that this changes the effective sampling rate of the returned data.Requesting 32 averages per sample, for example, divides the effectivesampling rate by 32. This is not reflected in the main window; the sampling rateyou select there is always the basic sampling rate, and not the effectivesampling rate after averaging.

The ADS1254EVM can only average samples in quantities which are powersof 2. This dramatically simplifies the averaging calculations that the board’smicrocontroller must perform. The allowable values are all shown in theAveraging menu; up to 32,768 samples per reading can be averaged together.Selecting none from the menu—the default—means that no averages aretaken, and data is returned as read from the ADS1254.

3.5.3.5 Serial Monitor

Checking this box causes the serial monitor window to appear when the setupdialog is closed. This window displays, as it occurs, all serial communicationsbetween the program and the ADS1254EVM, in hexadecimal bytes.

4-1Physical Description

This chapter contains the schematic drawings and PCB layouts for theADS1254EVM board.

Topic Page

4.1 Board Layouts 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.2 Schematics 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 4

Board Layouts

4-2

4.1 Board Layouts

Figure 4–1. Board Layout Top Layer

Board Layouts

4-3Physical Description

Figure 4–2. Board Layout Bottom Layer

Schematics

4-4

4.2 Schematics

The ADS1254 schematics are shown on the following pages.

Schematics

Figure 4-3. Schematic (Sheet 1 of 2)

Physical Description 4-5

12

34

56

ABCD

65

43

21

D C B A

RE

VIS

ION

HIS

TOR

YR

EV

EN

GIN

EE

RIN

G C

HA

NG

E N

UM

BE

RA

PPR

OVE

D

DVCC1

P6.

3/A

32

P6.

4/A

43

P6.

5/A

54

P6.

6/A

65

P6.

7/A

76

VREF+7

XIN8

XOUT/TCLK9

VEREF+10

VREF-/VEREF-11

P1.

0/TA

CLK

12

P1.

1/TA

013

P1.

2/TA

114

P1.

3/TA

215

P1.

4/S

MC

LK16

P1.

5/TA

017

P1.

6/TA

118

P1.

7/TA

219

P2.

0/A

CLK

20

P2.1

/TA

INC

LK21

P2.

2/C

AO

UT/

TA0

22

P2.

3/C

A0/

TA1

23

P2.

4/C

A1/

TA2

24

P2.

5/R

OS

C25

P2.

6/A

DC

12C

LK26

P2.

7/TA

027

P3.

0/S

TE0

28

P3.

1/S

IMO

029

P3.

2/S

OM

I030

P3.

3/U

CLK

031

P3.

4/U

TXD

032

P3.

5/U

RXD

033

P3.

6/U

TXD

134

P3.

7/U

RXD

135

P4.

0/TB

036

P4.

1/TB

137

P4.

2/TB

238

P4.

3/TB

339

P4.

4/TB

440

P4.

5/TB

541

P4.

6/TB

642

P4.

7/TB

CLK

43

P5.

0/S

TE1

44

P5.

1/S

IMO

145

P5.

2/S

OM

I146

P5.

3/U

CLK

147

P5.

4/M

CLK

48

P5.

5/S

MC

LK49

P5.

6/A

CLK

50

P5.

7/TB

OU

TH51

XT2OUT52

XT2IN53

TDO/TDI54

TDI55

TMS56

TCK57

RST/NMI58

P6.

0/A

059

P6.

1/A

160

P6.

2/A

261

AVSS62

DVSS63

AVCC64

U7

MS

P43

0F14

9IP

M

C2+1

GND2

C2-3

V-4

TOU

T15

TOU

T26

TOU

T37

RIN

18

RIN

29

TOU

T410

RIN

311

TOU

T512

FOR

CE

ON

13

FOR

CE

OFF

14IN

VALI

D15

RO

UT1

B16

TIN

517

RO

UT3

18

TIN

419

RO

UT2

20R

OU

T121

TIN

322

TIN

223

TIN

124

C1-25

VCC26

V+27

C1+28U8

MAX3238CPW3.

3Vdd

3.3V

dd

C18

1 uF

C20

1 uF

C15

1 uF

C16

.22

uFC17

1 uF

I/O0

21

I/O1

22

I/O2

23

I/O3

25

I/O4

26

I/O5

27

I/O6

28

I/O7

29

A0

20

A1

19

A2

18

A3

17

A4

16

A5

15

A6

14

A7

13

A8

3

A9

2

A10

31

A11

1

A12

12

A13

4

A14

11

A15

7

A16

10

VDD8

CE

26

CE

130

OE

32

WE

5

GND24

U10

CY6

2128

VLL-

70ZC

3.3V

dd

RA

M_D

0R

AM

_D1

RA

M_D

2R

AM

_D3

RA

M_D

4R

AM

_D5

RA

M_D

6R

AM

_D7

3.3V

dd

RA

M_A

0R

AM

_A1

RA

M_A

2R

AM

_A3

RA

M_A

4R

AM

_A5

RA

M_A

6R

AM

_A7

RA

M_A

8R

AM

_A9

RA

M_A

10R

AM

_A11

RA

M_A

12R

AM

_A13

RA

M_A

14R

AM

_A15

RA

M_A

16

RA

M_A

9R

AM

_A10

RA

M_A

11R

AM

_A12

RA

M_A

13R

AM

_A14

RA

M_A

15R

AM

_A16

C23

10 u

F

C21

10 u

F

RA

M_A

1R

AM

_A2

RA

M_A

3R

AM

_A4

RA

M_A

5R

AM

_A6

RA

M_A

7R

AM

_A8

X1

HC

M49

-8.0

00M

AB

JT

RA

M_C

E

RA

M_O

ER

AM

_WE

RA

M_C

ER

AM

_OE

RA

M_W

E

SP_

TXD

SP_

CTS

SP

_DS

RS

P_D

CD

SP_

RI

SP

_RXD

3.3V

dd

SP_

RTS

3.3V

dd

SP_DTR

SP_

RTS

SP_

TXD

SP_

TXD

SP_

CTS

SP

_DS

R

SP

_DC

D

SP_

RI

SP

_RXD

SP

_RXD

246

1357891011121314

J6 3.3V

JTA

G P

OR

T

RA

M_A

0M

CU

_EN

BL

TCK

3.3V

dd

RE

SE

T#

RE

SE

T#

RD

CTS

DS

RD

CD

RI

TDRTS

DTR

R17

10K

3.3V

dd

RA

M_A

[1..1

6]

1 6 2 7 3 8 4 9 5

DC

D

RD

TD DTR

SG

DS

R

RTS

CTS

RI

J7

7478

44-4

AVd

d

AVd

d

C10

10 u

F

3.3V

dd

C12

1 uF

AVD

D7

CH

1+1

CH

1-2

CH

2+3

CH

2-4

CH

3+5

CH

3-6

CH

4+20

CH

4-19

CH

S1

15

CH

S0

16

AG

ND

17

Vref

18

NC

10

NC

11

DVD

D9

DG

ND

12

CLK

8

SC

LK14

DO

UT

13

U5

AD

S12

54E

R5

1K R6

1K R7

1K R12

1KR8

1K R9

1K R10

1K R11

1K

C3

10 u

F

R2

10K

R1

5.1K

AVd

d

C9

1 uF

J1 PJ-

102B

BT1

9VC

1.1

uFC

4.3

3 uF

C7

10 u

FR

1322

0

C8

10 u

F

D3

SM

L-LX

1206

GC

-TR

D4

SM

L-LX

1206

GC

-TR

R14

390

AVd

d

3.3V

dd

C19

18pF

C14

18pF

SW

1

EVQ

-PJU

04K

6730

SO

UTH

TU

CS

ON

BLV

D.,

TUC

SO

N, A

Z 85

706

US

A

TITL

E

SH

EE

TO

FFI

LE

SIZ

ED

ATE

RE

V4

OC

T 20

01

EN

GIN

EE

R

B

DA

TA A

CQ

UIS

ITIO

N P

RO

DU

CTS

HIG

H P

ER

FOR

MA

NC

E A

NA

LOG

DIV

ISIO

N

R. A

ND

ER

SO

N

B

2

AD

S12

54E

VM

1

C2

.33

uF

12345678

J2 ED

120/

DS

8

DS

P_+

3.3V

DS

P_+

5V

DS

P_G

ND

2 36

7 4

U4

OPA

350E

A

1

2

J3

ED

120/

DS

2

GND3

VIN

5VO

UT

1

EN4

NR2

U1

RE

G10

3-5

C5

10 u

F

GND3

VIN

5VO

UT

1

EN4

NR2

U2

RE

G10

3-5

C6

10 u

F

24

5 3

U11

SN

74LV

C1G

07D

BV

24

5 3

U9

SN

74LV

C1G

07D

BV

1

2

J4 ED

120/

DS

2

1

2

J5 ED

120/

DS

2

R16

10 1

/4W

C11

10 u

F

L1

S18

12-1

04K

DA

TA O

UT

SE

RIA

L C

LK

3.3V

dd

24

53

U3

SN

74LV

C1G

07D

BV

R3

5.1K

3.3V

ddR

45.

1K

R19

10K

3.3V

dd

R21

10K

R23

10K

GR

EE

N

GR

EE

N

100

uH

RS

232

PO

RT

8 M

HZ

RE

SE

T

EXT

VR

EF

1 24

5 3

U6

SN

74LV

C1G

08D

BVR

M. A

SH

TON

PRO

DU

CT

EVA

LUAT

ION

FIX

TUR

ES

CH

EM

ATI

C D

IAG

RA

M

SE

MIC

ON

DU

CTO

R G

RO

UP

R15

10 1

/4W

12

JMP

5M

CU

DIS

AB

LE

CH

1+C

H1-

CH

2+C

H2-

CH

3+C

H3-

CH

4+C

H4-

CHS0CHS1

CH

S0

CH

S1

AD

CLK

RE

FCLK

12

JMP

4R

EF

DIS

CO

NN

EC

T

VREF

123JM

P1

RE

F S

EL

D1

LM40

40A

IM3-

4.1

XTAL

OU

T1

SC

LK2

GN

D3

DA

TA4

CLK

OU

T5

VDD

6

MU

XRE

F/O

E7

XTAL

IN8

U13

ICD

2053

BS

C

5Vdd

AD

CLK

ADCLK

CG

CLK

CG

SD

I

3.3V

dd

C27

1 uF

PLLE

N

C26

56P

F X7

R

3.3V

dd

POS

ITIO

N C

26 A

S C

LOS

ELY

AS

PO

SS

IBLE

TO

U13

NO

TE

UN

LES

S O

THE

RW

ISE

NO

TED

:

ALL

RE

SIS

TOR

S 1

/8W

5%

TH

IN-F

ILM

SU

RFA

CE

MO

UN

T (1

206)

ALL

10U

F C

AP

AC

ITO

RS

PA

NA

SO

NIC

EC

J-3Y

F1A

106Z

OR

EQ

UIV

. (12

06)

ALL

OTH

ER

CA

PAC

ITO

RS

MLC

SU

RFA

CE

MO

UN

T

2 4

15

3 U14SN74LVC1G125DBVR

3.3V

dd

D2

DL4

001

123

JMP

3A

VDD

SE

L

123

JMP

2D

VDD

SE

L

3.3V

dd

C13

1 uF

AD

CLK

VIN

3VO

UT

2

GND1

VOU

T4

U12

RE

G11

17-3

.3

C22

10 u

FC

2410

uF

5Vdd

5Vdd

3.3V

dd

EXT

DIG

ITA

L 5V

IN

+-

+-

DO

CU

ME

NT

CO

NTR

OL

NO

.64

3260

0

EXT

AN

ALO

G 5

V IN

TP1

TP2

TP3

TP4

TP6

TP5

SC

LKD

OU

T

DO

UT

SC

LK

ITE

XAS

NSTRUMENTS

Schematics

Figure 4-4. Schematic (Sheet 2 of 2)

4-6

12

34

56

ABCD

65

43

21

D C B A

HO

ST_C

LKXa

HO

ST_

DXa

HO

ST_

FSXa

HO

ST_

DR

a

12

34

56

78

910

1112

1314

1516

1718

1920

2122

2324

2526

2728

2930

3132

3334

3536

3738

3940

4142

4344

4546

4748

4950

5152

5354

5556

5758

5960

6162

6364

6566

6768

6970

7172

7374

7576

7778

7980

J9

12

34

56

78

910

1112

1314

1516

1718

1920

2122

2324

2526

2728

2930

3132

3334

3536

3738

3940

4142

4344

4546

4748

4950

5152

5354

5556

5758

5960

6162

6364

6566

6768

6970

7172

7374

7576

7778

7980

J10

HO

ST_

CLK

XaH

OS

T_D

XaH

OS

T_FS

Xa

PE

RIP

HE

RA

L / C

ON

TRO

L C

ON

NE

CTO

RM

EM

OR

Y IN

TER

FAC

E C

ON

NE

CTO

R

DSP

_GN

D

HO

ST_

CLK

Sa

12

34

56

78

910

1112

1314

1516

1718

1920

J8

DSP

_+5V

HO

ST_

DR

a

HO

ST_

CLK

Sa

SER

IAL

CLK

HO

ST_

DR

a

HO

ST_

CLK

Xa

DSP

_+3.

3V

MC

U_E

NBL

HO

ST_

FSR

a

HO

ST_

CLK

Ra

6730

SO

UTH

TU

CS

ON

BLV

D.,

TUC

SO

N, A

Z 85

706

US

A

TITL

E

SH

EE

TO

FFI

LE

SIZ

ED

ATE

RE

V4

OC

T 20

01D

OC

UM

EN

T C

ON

TRO

L N

O.

EN

GIN

EE

R

B

DA

TA A

CQ

UIS

ITIO

N P

RO

DU

CTS

HIG

H P

ER

FOR

MA

NC

E A

NA

LOG

DIV

ISIO

NS

EM

ICO

ND

UC

TOR

GR

OU

P

RU

SS

ELL

AN

DE

RS

ON

B

2

AD

S12

54E

VM

2

HO

ST_

CLK

OU

T

DAT

A O

UT

HO

ST_

CLK

OU

T

HO

ST_

CLK

Ra

HO

ST_

FSR

a

ADC

LK

6432

600

MIC

HA

EL

AS

HTO

NPR

OD

UC

T E

VALU

ATIO

N F

IXTU

RE

SC

HE

MA

TIC

DIA

GR

AM

ITE

XAS

NSTRUMENTS

IMPORTANT NOTICE

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TI warrants performance of its hardware products to the specifications applicable at the time of sale inaccordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TIdeems necessary to support this warranty. Except where mandated by government requirements, testing of allparameters of each product is not necessarily performed.

TI assumes no liability for applications assistance or customer product design. Customers are responsible fortheir products and applications using TI components. To minimize the risks associated with customer productsand applications, customers should provide adequate design and operating safeguards.

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Farnell | Electronic Component Distributors · 2009. 2. 27. · Information About Cautions and Warnings iii Preface About This Manual This users guide describes the function and operation