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Contents

Contents

Introduction

1-1

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1.1

The ADS1254

1-2

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1.2

EVM System Overview

1-2

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1.3

Analog Inputs

1-3

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1.4

Prototyping Area

1-3

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1.5

Power Requirements

1-3

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1.6

Host Computer Requirements

1-4

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Getting Started

2-1

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2.1

Unpacking the EVM

2-2

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2.2

Default Configuration

2-2

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2.3

Quick Start

2-3

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Operation

3-1

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3.1

Jumpers

3-2

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3.1.1

JMP1: Reference Source Select

3-2

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3.1.2

JMP2, JMP3: Power Source Select

3-2

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3.1.3

JMP4: Reference Disconnect

3-2

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3.1.4

JMP5: MCU Disable

3-3

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3.2

Reset Switch

3-4

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3.3

Connectors

3-4

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3.3.1

J7: RS-232 Connector

3-4

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3.3.2

J6: 3.3-V JTAG Port

3-5

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3.3.3

J1, J4, J5, BT1: Power Connectors

3-6

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3.3.4

J2: Analog Inputs

3-7

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3.3.5

J3: External Reference Input

3-7

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3.3.6

J8: External Digital Control

3-8

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3.3.7

J9, J10: DSK Motherboard Connectors

3-8

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3.3.8

TP1 −6: Test Point

3-9

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3.4

Circuit Description

3-10

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3.4.1

ADS1254

3-10

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3.4.2

Microcontroller

3-10

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3.4.3

Clock Generation

3-10

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3.4.4

Firmware and Host Communication

3-11

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3.4.5

Power Supply

3-11

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3.5

Host PC Software

3-12

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3.5.1

Main Window

3-12

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3.5.2

Display Modes

3-14

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3.5.3

Setup Dialog

3-15

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Содержание ADS1254

Страница 1: ... May 2002 Data Acquisition Products User s Guide SLAU083 ...

Страница 2: ...nt 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 process in which TI products or services are used Information published by TI regarding third party products or services does not constitute a license from TI to use such products or services or a warranty or end...

Страница 3: ... handling or use of the goods Please be aware that the products received may not be regulatory compliant or agency certified FCC UL CE etc Due to the open construction of the product it is the user s responsibility to take any and all appropriate precautions with regard to electrostatic discharge EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR A...

Страница 4: ...oad 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 than 40 C The EVM is designed to operate properly with certain components above 40 C as long as the input and output ranges are maintained These components include but are not limited to linear regulat...

Страница 5: ...y chapter which describes the EVM and what it can do If you are anxious to set things up and start testing we suggest you read at least the first two chapters These two chapters introduce you to the 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 des...

Страница 6: ...rsuant to subpart J of part 15 of FCC rules which are designed to provide reasonable protection against radio frequency interference Operation of this equipment in other en vironments may cause interference with radio communications in which case the user at his own expense will be required to take whatever measures may be required to correct this interference Trademarks Windows is a trademark of ...

Страница 7: ...ce 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...

Страница 8: ...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 Inpu...

Страница 9: ...rovides an overview of the ADS1254EVM evaluation module and 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 ...

Страница 10: ...Overview A block diagram of the ADS1254 evaluation module is shown in Figure 1 1 Figure 1 1 ADS1254EVM Block Diagram RS 232 Serial Port MSP430F149 Microcontroller 128 k 8 SRAM Clock Generator ADS1254 Reference Buffer Serial Data SPI Inputs Reference Inputs System Clock During normal operation data is read from the ADS1254 into the user s computer via the ADS1254EVMs RS 232 port Once read the data ...

Страница 11: ...LATED POWER UNREGULATED POWER JTAG ADS1254 BATTERY CONNECTOR MCU DISABLE VREF DISCONNECT VREF SOURCE SELECT DIGITAL VDD SOURCE ANALOG VDD SOURCE SRAM MCU DSK PERIPHERAL CONNECTOR DSK MEMORY CONNECTOR EXT DIGITAL 1 3 Analog Inputs Analog input is supplied through the eight way screw terminal block J2 Each input is connected to the ADS1254 through a 1 kΩ resistor The inputs are not protected against...

Страница 12: ...ADS1254EVM software is designed to run on a PC running any Windows 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 ...

Страница 13: ...tting Started This chapter guides you through unpacking your EVM and setting it up so you can 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 ...

Страница 14: ...n 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 sourc...

Страница 15: ...rial cable first it is also acceptable to apply power to the board first When the board is properly powered on the two power good indicator lamps near the power connectors glow brightly The 5 V LED may glow brighter than the 3 3 V LED this is normal Place the CD ROM into your PCs CD ROM drive Locate the setup program on the disk and run it The setup program installs the ADS1254EVM software on your...

Страница 16: ...ble a message box appears informing you that the program cannot run This is usually because other programs are using all of the available serial ports If this is the case closing these programs and rerunning the program should fix the problem Once the correct serial port has been selected click OK The setup dialog disappears and you see the main window Click the acquire button After a period of ac...

Страница 17: ... describes each function of the ADS1254EVM and how to use the accompanying 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 ...

Страница 18: ...d MCU does not control ADS1254 3 1 1 JMP1 Reference Source Select The ADS1254EVM can use an externally supplied reference or an onboard 4 096 V zener reference D1 and R1 use JMP1 to connect the desired reference 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 digita...

Страница 19: ... from the DSK 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 the onboard MCU you must connect this jumper to prevent conflicts with the MCU Since this jumper disables the onboard power supply you must also power the board externally If JMP5 is shorted and power is available to the MCU it is active but i...

Страница 20: ...ding to their logical states If a non handshaking RS 232 cable is used that is one which connects only RD TD and signal ground The board can still operate normally but it cannot be reset by the host PC and bootstrap firmware upgrading cannot be performed through the serial port it can still be done through the JTAG port J6 but this requires a special programming adapter and software Table 3 2 J7 R...

Страница 21: ...at board Function 1 TDI TDO Test data in out Output JTAG TDO port see JTAG standard 2 VCCTOOL Power from JTAG adapter 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 blowing the security fuse 4 VCCLOCAL Power sense from board Output High rail from board used for signal sense when board is using its ...

Страница 22: ...nce it is necessary to use an external supply for the analog circuitry when using the ADS1254EVM with a DSK Four power connectors are provided screw terminal blocks J4 and J5 for external power battery terminal BT1 for a 9 V transistor radio battery and J1 for a wall wart J1 is a switched jack connecting a plug to J1 automatically disconnects the battery terminal This prevents the battery and J1 f...

Страница 23: ...input 4 CH3 5 Channel 3 positive input 5 CH2 4 Channel 2 negative input 6 CH2 3 Channel 2 positive input 7 CH1 2 Channel 1 negative input 8 CH1 1 Channel 1 positive input 3 3 5 J3 External Reference Input The ADS1254EVM has an onboard 4 096 V bandgap reference If a lower noise reference source or a reference with a different voltage is desired it can be connected to screw terminal block J3 The ref...

Страница 24: ...mbered pins DGND DGND Power Signal ground 3 3 7 J9 J10 DSK Motherboard Connectors These two connectors are used as both electrical connection and mechanical support for plugging the ADS1254EVM into a DSP DSK Communication between a DSP on a DSK and the ADS1254 on the EVM is accomplished through these connectors J9 the memory interface connector carries the DSP external bus J10 the peripheral and c...

Страница 25: ...S1254 data sheet for information on the signals connected directly to the ADS1254 Table 3 11 TP1 6 Test Points Test Point Designator ADS1254 Pin Number ADS1254 Pin Name 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 ...

Страница 26: ...h 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 system clock s maximum specified rate is 8 MHz maximum sampling frequency is 20833 Hz up to this maximum virtually any sampling frequency may be selected by generating a clock of the appro...

Страница 27: ...ed power input J1 or through the DSK connectors J9 and J10 If a wall power adaptor is plugged into J1 the battery is disconnected Power supplied from the battery or through J1 is regulated by voltage regulators U1 U12 and U2 which provide 5 V digital and analog supplies and a 3 3 V digital supply Power supplied from the external connectors is not filtered regulated power of the correct voltages mu...

Страница 28: ...The window is shown as it first comes 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 is performed in the following sequence 1 The software configures the ADS1254EVM telling it what sampling rate to use how many averages to perform per sample this is configured in the Setup window and how...

Страница 29: ...is clicked The STOP button appears when 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 in the sample data rate edit box and press enter The program immediately requests that the board change to this sampling rate Not all sampling rates are realizable by the board that is the clock generator circuitry has a...

Страница 30: ...riginal scale Left clicking on the graph brings up a pop up menu containing numerous display options Double clicking with the right mouse button brings up an options dialog containing other display options You can export the graph in various 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 and displayed ...

Страница 31: ...ing 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 data may be shown in one of four modes As integers Each sample is displayed as a signed base 10 integer The sample values are shown exactly as received from the ADS1254 As hexadecimal integers Each sample is displayed as an unsigned hexadecimal number The hexadecimal val...

Страница 32: ...ire buttons to select which channel to read when performing an acquisition 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 value is used in certain display calculations You must input the correct reference voltage here because the board cannot detect the reference voltage so the software has no way to obtain ...

Страница 33: ...ctually 32 successive samples averaged together so for that acquisition 8 192 samples 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 effective sampling rate by 32 This is not reflected in the main window the sampling rate you select there is always the basic sampling rate and not the effecti...

Страница 34: ...3 18 ...

Страница 35: ...4 1 Physical Description Physical Description This chapter contains the schematic drawings and PCB layouts for the ADS1254EVM board Topic Page 4 1 Board Layouts 4 2 4 2 Schematics 4 4 Chapter 4 ...

Страница 36: ...Board Layouts 4 2 4 1 Board Layouts Figure 4 1 Board Layout Top Layer ...

Страница 37: ...Board Layouts 4 3 Physical Description Figure 4 2 Board Layout Bottom Layer ...

Страница 38: ...Schematics 4 4 4 2 Schematics The ADS1254 schematics are shown on the following pages ...

Страница 39: ...AG PORT RAM_A0 MCU_ENBL TCK 3 3Vdd RESET RESET RD CTS DSR DCD RI TD RTS DTR R17 10K 3 3Vdd RAM_A 1 16 1 6 2 7 3 8 4 9 5 DCD RD TD DTR SG DSR RTS CTS RI J 7 747844 4 AVdd AVdd C10 10 uF 3 3Vdd C12 1 uF AVDD 7 CH1 1 CH1 2 CH2 3 CH2 4 CH3 5 CH3 6 CH4 20 CH4 19 CHS1 15 CHS0 16 AGND 17 Vref 18 NC 10 NC 11 DVDD 9 DGND 12 CLK 8 SCLK 14 DOUT 13 U5 ADS1254E R5 1K R6 1K R7 1K R12 1K R8 1K R9 1K R10 1K R11 1...

Страница 40: ... 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 J10 HOST_CL K X a HOST_DX a HOST_FSX a PERIPHERAL CONTROL CONNECTOR MEMORY INTERFACE CONNECTOR DSP_GND HOST_CLK Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 J8 DSP_ 5V HOST_DRa HOST_CLK Sa SERIALCLK HOST_DRa HOST_CL K X a DSP_ 3 3V MCU_ENBL HOST_FSRa HOST_CLK Ra ti 6730 SOUTH TUCSON BL V D TUCSON AZ 85706 USA TITLE SHEET OF FILE SIZE DAT...

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