Harris Data Acquisition Authors: David Jarman John Kornblum

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Harris Data Acquisition Authors: David Jarman John Kornblum

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AN9505
Harris Data Acquisition
Authors: David Jarman John Kornblum
USING HI7190 EVALUATION
Evaluation Description
HI7190 evaluation (evaluation board evaluation software) used evaluate performance HI7190 24-bit sigma delta analog-to-digital converter (ADC). evaluation board includes reference circuit, crystal, oscillator, digital circuitry used interface personal computer running evaluation software. board also provides means user supply external reference external clock. Layout Power Supplies HI7190 evaluation board consists layers laid optimize performance ADC. figures this document include various layers board their layout, list board components, schematics. Users should feel free copy this layout their applications. power supplies provided board edge connector located board. recommended that twisted pair wires used connect power supplies connector that analog digital grounds tied together back power supplies. separate supplies necessary keep digital noise from coupling into analog portions circuit. internal layers board ground plane layer. This layer roughly divided half with half layer being digital ground other half being analog ground. other internal layer power plane. divided into three sections; AVDD, AVSS, DVDD. Nominal values supplies AVDD +5V, AVSS -5V, DVDD +5V. some cases (for instance there substantial offset between AGND DGND) necessary grounds together board. Resistors provide means connecting ground planes together through impedance. prototype area provided left side board. This area small section analog ground plane center useful input signal conditioning before HI7190. Reference Circuit reference inputs HI7190, VRHI VRLO, provide differential reference input capability. reference inputs provide high impedance dynamic load similar analog inputs. proper circuit operation these pins must driven impedance circuitry. Reference noise outside band interest will removed chip digital filter excessive reference noise inside band interest will degrade performance HI7190. actual reference voltage given VREF VRHI VRLO. VRLO hard wired analog ground evaluation board which means that VREF VRHI. nominal reference voltage HI7190 2.5V. Larger values VREF
HI7190 Description
HI7190 24-bit sigma delta intended applications such industrial weight scales, process controls, process measurement systems. block diagram shows that device consists programmable gain instrumentation amplifier (PGIA), second order sigma delta modulator, digital filter, clock generator, digital control interface circuitry. input signal applied VINHI VINLO pins comes into PGIA where gained factor resulting signal then passed into oversampling second order sigma delta modulator conversion noise shaping. output modulator serial stream "1"s "0"s whose code density direct indication value input modulator. This stream then input digital filter where band limited decimated down lower frequency. digital filter also used (along with PGIA) implement gains 128. clock generator digital control circuits direct internal conversion process while serial interface unit provides access device from outside world. detailed description operation converter, please refer HI7190 data sheet.
Hardware Description
HI7190 evaluation board provides user with very simple interfacing evaluating Harris HI7190 sigma delta ADC. board features reference voltage generator, crystal oscillator, digital line drivers receivers interfacing running evaluation software. board consists layers with separate analog digital ground planes obtaining optimum noise performance.
Copyright
Harris Corporation 1995
Application Note 9505 HI7190 Functional Block Diagram
VRHI AVDD TRANSDUCER BURN-OUT CURRENT (100nA) VRLO
REFERENCE INPUTS
MODULATOR
PGIA VINHI VINLO
1-BIT
DIGITAL FILTER
CONTROL SERIAL INTERFACE UNIT
SERIAL INTERFACE UNIT CLOCK GENERATOR CONTROL REGISTER
OSC1
OSC2
DRDY RESET SYNC
MODE
SCLK
SDIO
HI7190 Evaluation Board Block Diagram
CRYSTAL OSCILLATOR EXTERNAL CLOCK CRYSTAL
AIN+ AIN-
VINHI VINLO
OSC1 OSC2
BOARD REFERENCE VRHI EXTERNAL VREF VRLO DIGITAL
LINE DRIVERS RECEIVERS
AGND HI7190
DGND
Application Note 9505
used without degradation performance. Smaller values VREF also used performance will degraded since system noise becomes larger relative size. jumper controls whether VRHI HI7190 connected external reference, which connects VREF pad, board reference which preset 2.5V. right position VRHI connected board noise reference when left position VRHI connected external reference. external reference used recommended that twisted pair wire used soldered directly evaluation board. potentiometer used vary board reference voltage. Please note that specifications HI7190 tested with VRHI 2.5V. VRHI must always greater than VRLO proper operation device. Analog Inputs analog input HI7190 fully differential input with programmable gain capabilities. input accepts both unipolar bipolar input signals gains range from 128. user must careful attention input driver and/or input filter circuitry input sampling rate modulator clock rate) varies with selected PGIA gain, input impedance dependent upon modulator clock rate. Please refer data sheet more information. analog inputs come onto board pads labeled AIN+ AIN-. Once again recommended that twisted pair wire used drive positive negative analog inputs. Common Mode Input jumper provided allow tied either analog ground (upper position), VRHI (lower position). input voltage should always midpoint between AVDD AVSS. AVDD AVSS -5V, should analog ground. Please note HI7190 specified AVDD AVSS operation only. Clock Input master clock into HI7190 supplied either crystal connected between OSC1 OSC2 pins CMOS compatible clock signal connected OSC1 pin. input sampling frequency, modulator clock frequency, filter -3dB frequency, output update rate, calibration times directly related master clock frequency, fOSC. example, 1MHz clock used instead 10MHz clock, what normally 10Hz conversion rate becomes conversion rate. Lowering clock frequency will also lower power supply currents. Please note that HI7190 specifications written 10MHz clock only. HI7190 evaluation board allows HI7190 master clock supplied externally, generated board crystal oscillator, generated board crystal used conjunction with chip oscillator circuitry. jumper must removed from board when using external clocking source external clocking source must disconnected from board when using either board clocking methods. When right most position 10MHz crystal oscillator selected when left most position combination 10MHz crystal chip oscillator clocking method selected. external clock used from minimum frequency 1MHz maximum frequency 10MHz. best noise performance crystal should removed from board when using crystal oscillator vice versa. Both crystal crystal oscillator should removed when using external clock. Digital Inputs/Outputs digital input output pins HI7190 interfaced through line drivers receivers connector right edge board. These pins activated deactivated evaluation software which controls functionality HI7190. Please refer HI7190 data sheet detailed description functionality these pins. evaluation board "open socket" which used conjunction with test modes HI7190 Harris internal testing evaluation.
Software Description
software provided with HI7190 evaluation allows user operate device many various modes part supports. software menu driven ease use. simplified flow diagram shown Figure gives good feel structure software. Every menu allows access other menus.
MAIN MENU
READ MENU RESET
CHANGE MODE MENU EXIT PROGRAM
WRITE MENU
FIGURE SIMPLIFIED SOFTWARE FLOW CHART
Main Menu appears after invoking HI7190 evaluation software. This menu gateway other menus that allow user communicate with HI7190. Main Menu: Reset Change Mode Menu
Write Menu Read Menu Exit
Application Note 9505
Entering from Main Menu sends active reset signal HI7190 which initializes HI7190. Entering from Main Menu brings Change Mode Menu Change Mode Menu allows user custom configure HI7190 without having know positions Control Register. Entering from Change Mode Menu initiates communication cycle with HI7190 that invokes System Negative Full Scale Calibration Mode with notch frequency 10Hz. Other operating parameters offset binary coding, bipolar mode gain one. Please note, user should apply negative full scale voltage HI7190 inputs before issuing this command. Executing this command returns user Main Menu. Entering from Change Mode Menu allows user customize operational parameters HI7190. user will asked series questions relating HI7190 operation. After completing these questions, software compiles proper data writes Control Register invoke desired operating mode. Executing this command returns user Main Menu. Entering from Change Mode Menu invokes Read Menu.
Entering from Main Menu brings Write Menu Write Menu allows user write access writable registers without having knowledge specific Instruction Register address details. Entering from Main Menu brings Read Menu Read Menu allows user read registers without having knowledge specific Instruction Register address details. Entering from Main Menu exits program.
Change Mode Menu: Self Calibration 10Hz Self Calibration 2kHz System Offset Calibration 10Hz System Positive Full Scale Calibration 10Hz System Negative Full Scale Calibration 10Hz Custom Menu Read Menu
Entering from Change Mode Menu invokes Write Menu. Entering from Change Mode Menu invokes Main Menu. Entering from Change Mode Menu exits program.
Write Menu: Command Register Offset Register Positive Full Scale Register Negative Full Scale Register Read Menu Exit Program Entering from Write Menu invokes write communication cycle with Control Register. user will prompted data write. software requires data entered hex, most significant least significant format. Control Register bytes. three bytes must entered prompt. Entering from Write Menu invokes write communication cycle with Offset Calibration Register. user will prompted data write. software requires data entered hex, most significant least significant format. Offset Calibration Register bytes. three bytes must entered prompt. Entering from Write Menu invokes write communication cycle with Positive Full Scale Calibration Register. user will prompted data write. software requires data entered hex, most significant least significant format. Positive Full Scale Calibration Register bytes. three bytes must entered prompt. Entering from Write Menu invokes write communication cycle with Negative Full Scale Calibration Register. user will prompted data write. software requires data entered hex, most
Write Menu Main Menu Exit Program Entering from Change Mode Menu initiates communication cycle with HI7190 that invokes Self Calibration Mode with notch frequency 10Hz. Other operating parameters offset binary coding, bipolar mode gain one. Executing this command returns user Main Menu. Entering from Change Mode Menu initiates communication cycle with HI7190 that invokes Self Calibration Mode with notch frequency 2kHz. Other operating parameters offset binary coding, bipolar mode gain one. Executing this command returns user Main Menu. Entering from Change Mode Menu initiates communication cycle with HI7190 that invokes System Offset Calibration Mode with notch frequency 10Hz. Other operating parameters offset binary coding, bipolar mode gain one. Please note, user should apply HI7190 inputs before issuing this command. Executing this command returns user Main Menu. Entering from Change Mode Menu initiates communication cycle with HI7190 that invokes System Positive Full Scale Calibration Mode with notch frequency 10Hz. Other operating parameters offset binary coding, bipolar mode gain one. Please note, user should apply positive full scale voltage HI7190 inputs before issuing this command. Executing this command returns user Main Menu.
Main Menu
Application Note 9505
significant least significant format. Negative Full Scale Calibration Register bytes. three bytes must entered prompt. Entering from Write Menu invokes Main Menu. Entering from Write Menu invokes Read Menu. Entering from Write Menu exits program. touched abort reads. generally expected that this register will read continuous mode. Entering from Read Menu invokes read communication cycle with Negative Full Scale Calibration Register. user will asked continuous read required. continuous read requested, executing this command will invoke single read Negative Full Scale Calibration Register, display data return execution Main Menu. continuous read requested, read executions will continue until touched abort reads. generally expected that this register will read continuous mode.
Read Menu: Data Output Register, `Read Once' Data Output Register, `Read Continuous' Command Register Offset Calibration Register Positive Full Scale Register Negative Full Scale Register
Examples: Write (hex) Offset Calibration Register then read back. accomplish this task, choose Write Menu option from Main Menu, choose Offset Register option from Write Menu. Enter 000008 prompt. program returns Main Menu. select Read Menu option from Main Menu, choose Offset Register option from Read Menu. user will prompted decide upon single read continuous read. Enter single read. data read will displayed screen program will return Main Menu. Configure device bipolar mode, offset binary coding, 10Hz filter notch frequency, gain conversion mode operation. Select Change Mode Menu option from Main Menu then Custom Menu option from Change Mode Menu. When prompted data coding enter offset binary. next prompt enter notch frequency, enter 10Hz. Next, operational mode table displayed, choose conversion mode. next prompt bipolar/unipolar operation, enter bipolar mode. next screen displays gain selection table, enter gain equal program determines data required configure HI7190 user specified invokes proper communication cycle. Execution returns Main Menu.
Main Menu Write Menu Exit Program Entering from Read Menu invokes read communication cycle with Data Output Register. Data Output Register will read time, data will displayed, program will return Main Menu. Entering from Read Menu invokes continuous read communication cycles with Data Output Register. Refer Software Clarifications section this document details displayed data. Continuous data reads will displayed until pressed. When pressed, program returns Main Menu. Entering from Read Menu invokes read communication cycle with Control Register. user will asked continuous read required. continuous read requested, executing this command will invoke single read Control Register, display data return execution Main Menu. continuous read requested, read executions will continue until touched abort reads. generally expected that this register will read continuous mode. Entering from Read Menu invokes read communication cycle with Offset Calibration Register. user will asked continuous read required. continuous read requested, executing this command will invoke single read Offset Calibration Register, display data return execution Main Menu. continuous read requested, read executions will continue until touched abort reads. generally expected that this register will read continuous mode. Entering from Read Menu invokes read communication cycle with Positive Full Scale Calibration Register. user will asked continuous read required. continuous read requested, executing this command will invoke single read Positive Full Scale Calibration Register, display data return execution Main Menu. continuous read requested, read executions will continue until
Software Execution
PORT_ID.DAT file contains port identification parallel printer port interfacing HI7190 Evaluation board This file needs edited discussed HI7190RDME.TXT file) before running software. command used find printer port identification. Loading Software: Copy four files (7190BTA5.CPP, 7190BTA5.EXE, PORT_ID.DAT, 7190RDME.TXT) from diskette onto your hard drive into directory your choice. file 7190BTA5.CPP evaluation software source code. file 7190BTA5.EXE executable program 7190RDME.TXT README file containing valuable information. Please read 7190RDME.TXT file before continuing.
Application Note 9505
Executing Program: Change directory (cd) into directory containing 7190BTA5.EXE file. prompt type 7190BTA5 [return]. software reminds user apply power board before continuing. this point software menu driven self explanatory. However, important that user read previous section, Software Description, before starting evaluation. Bypassing Calibration HI7190 calibration algorithm effectively bypassed writing zeros into Offset Calibration Register 800000 (hex) into Positive Negative Full Scale Calibration Registers operating bipolar mode. operation unipolar mode write zeros into Offset Calibration Register 800000 (hex) into Positive Full Scale Calibration Register. Display Data Register Continuous Mode Entering from Read Menu invokes continuous read Data Register. following data displayed: binary output stream read from HI7190, binary output stream converted hex, binary output stream converted volts, mean voltage last conversion results, maximum voltage result, minimum voltage result, difference between maximum voltage minimum voltage, standard deviation, dynamic range ENOB, which updated groups conversions.
NOTE: CTRL input keyboard used "normalize" statistical output. example, maximum voltage 5.5V minimum -5.5V. maximum/minimum results displayed from then will include only those conversions read since "normalization".
Software Clarifications
Resetting Entering from Main Menu resets HI7190 initial state. initial state HI7190 follows: offset binary data coding, notch frequency 30Hz, Self Calibration mode, gain bipolar mode. burn-out current sleep mode bits inactive. Serial Interface configuration first positioning, descending byte order, bidirectional pin. Writing Control Register Caution should taken when writing Control Register Write Menu. least significant byte contains information regarding Serial Interface configuration that must maintained when running software provided. insure proper functionality evaluation software, Serial Interface must configured first mode, descending byte order bidirectional operation. This configuration maintained writing logic zeros into least significant bits Control Register. Invalid Inputs Entering invalid inputs some menu prompts will lock software. Generally CTL-C will return user prompt. Notch Frequency Input When executing from Custom Menu Change Mode Menu) notch frequency value must entered decimal. That 2kHz entered 2000.
Dynamic Range ENOB Equations follows:
Dynamic Range 10log10 REFNOISE Dynamic Range 1.76 ENOB -6.02 -6.6 REFNOISE (0.275 4.452
Notch Frequency
SMA3 CLOCK CRYSTAL FOSC DGND +5VD XTAL SMA1
ANALOG
SMA2
JMP3
CON1 CLOCK
ANALOG INSMA HI7190 CON1 CON1 CON1 MODE SCLK SDIO DRDY' SYNC' RESET' OSC1 4.7µF INHI INLO DRDY_ SYNC_ RESET_ DGND VRLO AVSS AGND SMA4 VREF JMP3 SCLK< MODE OSC2 DVDD 4.7µF +5VD 0.01µF
0.01µF
Application Note 9505
JMP3 0.1µF
0.01µF
VOUT
TRIM
1N4000
1N4000
4.7µF
0.01µF
+5VD
+5VD CONNECTOR EDGE44AB
1N4000
CON2 74HC125 SOCKET_16 74HC125
MODE
SCLK
Application Note 9505
DRDY'
SYNC'
74FCT244
+5VD
RESET'
74HC125
2.7k 74HC125 CON1 CON2 2.7k OPTION2 CON1 DRDY 2.7k +5VD
CONNECTOR DB25
SDIO
Application Note 9505 HI7090 Evaluation Board
COMPONENTS LAYOUT
COMPONENT SIDE
GROUND PLANES
Application Note 9505 HI7090 Evaluation Board (Continued)
POWER PLANE
SOLDER SIDE
Application Note 9505
HI7190 EVALUATION BOARD COMPONENT LIST ITEM QUANTITY REFERENCE JP1, JP4, 0.01µF 10µF Tantalum 0.1µF 1N4000 JMP3 Strip CON2 Wire Strap Connector Edge 44AB Connector DB25 2.7K 49.9 HI7190 (LT1019CN8-2.5) XTAL 10MHz 74HC244 (HARRIS) 74HC125 (HARRIS) Crystal 10MHz PART
Harris Semiconductor products sold description only. Harris Semiconductor reserves right make changes circuit design and/or specifications time without notice. Accordingly, reader cautioned verify that data sheets current before placing orders. Information furnished Harris believed accurate reliable. However, responsibility assumed Harris subsidiaries use; infringements patents other rights third parties which result from use. license granted implication otherwise under patent patent rights Harris subsidiaries.
Sales Office Headquarters
general information regarding Harris Semiconductor products, call 1-800-4-HARRIS UNITED STATES Harris Semiconductor 883, Mail Stop 53-210 Melbourne, 32902 TEL: 1-800-442-7747 (407) 729-4984 FAX: (407) 729-5321 EUROPE Harris Semiconductor Mercure Center 100, Fusee 1130 Brussels, Belgium TEL: (32) 2-724-2111 SOUTH ASIA Harris Semiconductor H.K. Ltd. 13/F Fourseas Building 208-212 Nathan Road Tsimshatsui, Kowloon Hong Kong TEL: (852) 723-6339 NORTH ASIA Harris K.K. Kojimachi-Nakata Bldg. 5-3-5 Kojimachi Chiyoda-ku, Tokyo Japan TEL: (81) 3-3265-7571 TEL: (81) 3-3265-7572 (Sales)

Harris Data Acquisition Authors: David Jarman John Kornblum

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