PRACTICAL DESIGN TECHNIQUES FOR SENSOR SIGNAL CONDITIONING

Transcription

1 9 PRACTICAL DESIGN TECHNIQUES FOR SENSOR SIGNAL CONDITIONING 1 Introduction 2 Bridge Circuits 3 Amplifiers for Signal Conditioning 4 Strain, Force, Pressure, and Flow Measurements 5 High Impedance Sensors 6 Position and Motion Sensors 7 Temperature Sensors 8 ADCs for Signal Conditioning Smart Sensors 10 Hardware Design Techniques a 9.0

2 CONTROLLING A REMOTE ACTUATOR USING A 4-20mA LOOP LOOP SUPPLY CONTROL ROOM 12V TO 32V 4-20mA OUTPUT R SENSE AD420 REGULATOR ACTUATOR 4-20mA DAC µc HOST COMPUTER LOOP RETURN a 9.1

3 4-20mA LOOP POWERED SMART SENSOR AD7714/AD7715 DMOS FET LOOP POWER CONTROL ROOM 3.3V / 5V AD421 LOOP SUPPLY REGULATOR SENSOR ADC µc 4-20mA DAC R SENSE 4-20mA RETURN ADC µc HOST COMPUTER I COMMON R SENSE I AD421 < 0.75mA I AD7714/AD7715 < 0.50mA I µc+sensor I COMMON < 2.75mA < 4.00mA DMOS FET: Supertex DN2535 Siliconix ND2020L or ND2410L a 9.2

4 HART INTELLIGENT REMOTE TRANSMITTER USING AD421 LOOP-POWERED 4-20mA DAC LOOP POWER SENSOR ADC µc 4-20mA DAC AD421 LOOP RETURN C C HART MODEM BELL 202 WAVEFORM SHAPER BANDPASS FILTER HT20C12 / 20C15 (Symbios Logic) HART DIGITAL SIGNAL: 1200Hz, 2200Hz FREQUENCY SHIFT KEYING (FSK) a 9.3

5 INDUSTRIAL NETWORKING BRANCH FIELD NETWORK NODE NODE DEVICE NETWORK NODE NODE SMART SENSOR SMART SENSOR SMART SENSOR SMART SENSOR a 9.4

6 SOME OF THE STANDARDS Ethernet CAN-Bus Foundation Fieldbus Device-Net Lonwork WorldFIP Profibus P-NET Interbus-S HART Universal Serial Bus (USB) ASI a 9.5

7 THE IEEE SENSOR INTERFACE STANDARD NCAP FIELD NETWORK - OR - DEVICE NETWORK TII NCAP = Network Capable Application Processor TEDS STIM Sensor or Actuator TII = Transducer Independent Interface TEDS = Transducer Electronic Datasheet STIM = Smart Transducer Interface Module a 9.6

8 TRUE "PLUG AND PLAY" Ethernet Field Network Lonwork Field Network Ethernet NCAP Ethernet NCAP Lonwork NCAP Lonwork NCAP Flow Rate STIM Temperature STIM Pressure STIM PC with Web Browser a 9.7

9 THE SMART SENSOR Pressure Sensor, RTD, Thermocouple, Strain Gage, etc. Precision Amplifier High Resolution ADC Microcontroller Sensor a 9.8

10 THE EVEN SMARTER SENSOR Pressure Sensor, RTD, Thermocouple, Strain Gage, etc. MicroConverter TM! Sensor a 9.9

11 THE MicroConverter 1 High Performance Analog I/O On-Chip FLASH Memory + On-Chip Microcontroller = MicroConverter a 9.10

12 ANALOG I/O 1 ADuC816 ADuC812 ADuC810 Dual Σ ADC >16 bit >100dB SNR (p-p) Differential Inputs Prog. Gain Amp Self-Calibration 8 chan SAR ADC 12 bit, 5µs < ½ LSB INL DMA mode Self-Calibration 8 chan SAR ADC 10 bit < ½ LSB INL 12bit V-Out DAC < ½ LSB DNL Dual 12bit V-Out DAC < ½ LSB DNL 12bit V-Out DAC < ½ LSB DNL Voltage Reference Voltage Reference Voltage Reference Temperature Sensor Temperature Sensor Temperature Sensor a 9.11

13 ON-CHIP FLASH MEMORY 2 ADuC816 ; ADuC812 ; ADuC810 8K bytes Nonvolatile FLASH Program Memory Stores Program and Fixed Lookup Tables In-Circuit Serial Programmable or External Parallel Programmable Read-Only to Microprocessor Core 640 bytes Nonvolatile FLASH Data Memory User Scratch Pad for Storing Data During Program Execution Simple Read / Write Access Through SFR Space Programming Voltage (V PP ) Generated On-Chip a 9.12

14 ON-CHIP MICROCONTROLLER 3 ADuC816 ; ADuC812 ; ADuC810 Industry Standard 8052 Core 12 Clock Machine Cycle w/ up to 16MHz Clock 32 Digital I/O Pins Three 16bit Counter/Timers Universal Asynchronous Receiver/Transmitter (UART) Serial Port...Plus Some Useful Extras SPI or I2C Compatible Serial Interface WatchDog Timer Power Supply Monitor Timer Interval Counter (ADuC816/810) a 9.13

15 ADuC816 FUNCTIONAL BLOCK DIAGRAM P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 AIN1 AIN2 AIN MUX (primary channel) P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 buf pga Σ ADC ADC control and calibration ADuC816 AIN3 AIN4 AIN MUX buf (auxilliary channel) Σ ADC ADC control and calibration DAC control DAC1 buf DAC V REF IN+ V REF IN I EXC 1 I EXC 2 TEMP sensor 3.5mV/ C 2.5V bandgap reference V REF detect 8K x 8 program FLASH EEPROM 640 x 8 user FLASH synchronous serial interface (SPI or I2C) 8052 microcontroller core 256 x 8 user RAM watchdog timer power supply monitor asynchronous serial port (UART) 16 bit counter timers timer interval counter OSC & PLL T0 T1 T2 T2EX INT0 INT P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0 P3.1 P3.2 P3.3 P3.4 P3.5 P3.6 P AV DD AGND a 9.14 DV DD DGND SCLK SDATA/ MOSI MISO SS ALE PSEN EA RESET RxD TxD XTAL1 XTAL2

16 ADuC816 - PRIMARY SPECIFICATIONS ADC : INL - ± 30ppm SNR (p-p) - >102dB (17 Noise Free Bits) Input Range - ± 20mV to ± 2.56V Conv. Rate - 5.4Hz to 105Hz DAC : DNL - ± ½LSB Output Range - 0 to V REF -or- 0 to V DD Settling Time - <4µs Power : Specified for 3V or 5V Operation 5V 3V Normal 7mA 3mA Idle 4.5mA 1.5mA Powerdown <20µA <20µA a 9.15

17 ADuC812 FUNCTIONAL BLOCK DIAGRAM P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0 P3.1 P3.2 P3.3 P3.4 P3.5 P3.6 P3.7 hardware CONVST ADC0 ADC1 ADC2 ADC3 ADC4 ADC5 ADC6 ADC AIN MUX TEMP sensor 2.5V bandgap reference T/H 3.5mV/ C bit ADC ADuC812 ADC control and calibration 8K x 8 program FLASH EEPROM 640 x 8 user FLASH microcontroller core DAC control x 8 user RAM watchdog timer DAC1 power supply monitor DAC0 buf 9 DAC0 buf 16 bit counter timers DAC1 T0 T1 T2 T2EX INT0 V REF C REF 8 7 buf synchronous serial interface (SPI or I2C) asynchronous serial port (UART) OSC 19 INT1 AV DD AGND SCLK SDATA/ MOSI MISO a 9.16 DV DD DGND SS ALE PSEN EA RESET RxD TxD XTAL1 XTAL2

18 ADuC812 - PRIMARY SPECIFICATIONS ADC : INL - ± ½LSB SNR (p-p) - >70dB Input Range - 0 to V REF Conv. Time - <5µs (200kSPS) DAC : DNL - ± ½LSB Output Range - 0 to V REF -or- 0 to V DD Settling Time - <4µs Power : Specified for 3V or 5V Operation 5V 3V Normal 18mA 12mA Idle 10mA 6mA Powerdown <50µA <50µA a 9.17

19 MicroConverter DESIGN SUPPORT MicroConverter TM Web Site 1 QuickStart TM Development Kit 2 Third Party Development Tools 3 a 9.18

20 MicroConverter WEB SITE 1 Data Sheets Application Notes 8051 Reference Material Free Windows MicroConverter TM Simulator Free Keil C Compiler (2K limited version) a 9.19

21 MicroConverter - QuickStart DEVELOPMENT KIT Documentation User s Guide Datasheet Tools Tutorial Quick Reference Guide Evaluation Board RS-232 Serial Comms 32K External SRAM Buffered Analog I/O Regulated Power Supply Serial Port Cable QuickStart TM 2 Software Metalink Assembler C Compiler (Limited 2K) Windows Simulator Serial Downloader Windows Debugger Example Code a 9.20

22 MicroConverter - THIRD PARTY DEVELOPMENT TOOLS The First Two of Many Third Party Tools to Fully Support MicroConverter TM Products: Power Tools 3 Keil Compiler A full function windows based C compiler environment featuring a simulator for source and assembly level debugging. MetaLink Emulator A high end in circuit emulation system offering a complete windows based environment for in-system debug sessions. All tools will fully integrate with each MicroConverter product a 9.21

23 MicroConverter PRODUCT ROADMAP TIME ADuC812-8 Channel 12 bit ADC - Dual DAC ADuC816 - Dual 16 bit + Σ ADC - Single DAC ADuC810 - Low Cost - 10 bit ADC, Dual DAC Future Products May Include: Larger FLASH Memory Capacity (Data and Program) Hardware Communications Interface Enhancements (CAN Bus, USB Bus) Increased Microcontroller Horsepower a 9.22