Analog Devices: CN0189 Reference Design for Tilt Measurement Using a Dual Axis Accelerometer

atomar — Sun, 27 Oct 2013 06:01:50 GMT

Current Revision posted to Documents by atomar on 10/27/2013 6:01:50 AM

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Kit Overview

The Evaluation circuit (EVAL-CN0189-SDPZEVAL-CN0189-SDPZ) incorporates a dual axis ADXL203ADXL203 accelerometer and the AD7887AD7887 12-bit successive approximation (SAR) ADC to create a dual axis tilt measurement system.

The ADXL203ADXL203 is a polysilicon surface micro machined sensor and signal conditioning circuit. Acceleration in the X or Y axis will produce a corresponding output voltage on the XOUT or YOUT output pins of the device. The X axis and Y axis are perpendicular to one another. The AD8608AD8608 quad op amp buffers, attenuates, and level shifts the ADXL203CEADXL203CE outputs so they are at the proper levels to drive the inputs of the AD7887AD7887. The rail-to-rail input/output AD8608ARUZ.AD8608ARUZ. is chosen for its low offset voltage (65 μV maximum), low bias current (1 pA maximum), low noise (8 nV/√Hz), and small footprint.

The AD7887AD7887 is configurable for either dual or single channel operation via the on-chip control register. In this application it is configured for dual channel mode, allowing the user to monitor both outputs of the ADXL203ADXL203, thereby providing a more accurate and complete solution.

The system maintains an accuracy of 1° over 90° and over temperature. The circuit provides this precision, performance, and range in a low cost, low power, small footprint, calibration dependent solution.

The evaluation circuit uses the EVAL-CN0189-SDPZEVAL-CN0189-SDPZ circuit board and the EVAL-SDP-CB1ZEVAL-SDP-CB1Z System Demonstration Platform (SDP-B) evaluation board (Should be purchased separately). The two boards have 120-pin mating connectors, allowing for the quick setup and evaluation of the circuit’s performance. The EVAL-CN0189-SDPZ board contains the circuit to be evaluated and the SDP evaluation board is used with the CN-0189 evaluation software to capture the data from the EVAL-CN0189-SDPZ circuit board.

Key Applications: Patient Monitoring, Rollover/Stability Control, Sensors and Sensor Interface

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Development Tools

PC with a USB port and Windows® XP or Windows Vista® (32-bit), or Windows® 7 (32-bit)
EVAL-CN0189-SDPZEVAL-CN0189-SDPZ circuit evaluation board
EVAL-SDP-CB1ZEVAL-SDP-CB1Z SDP evaluation board
- Blackfin Processor ADSP-BF527
- USB 2.0 Interface to PC
- JTAG header footprint
- 32MB SDRAM
- 2 x Small Footprint 120 Pin Connectors
- Configurable Peripheral Interfaces - SPI - SPORT - I2C - GPIOs - Parallel - Timers
CN-0189 evaluation software
Power supply: +6 V, or +6 V “wall wart” (EVAL-CFTL-6V-PWRZEVAL-CFTL-6V-PWRZ)

Technical Documents

Learning Center

Type	Description
User Manual	ADI: User Manual for CN-0189 Tilt Measurement Using a Dual Axis Accelerometer
User Guide	ADI: User Guide for EVAL-SDP-CB1Z
User Guide	ADI: Getting Started with SDP
Datasheet	ADI: Datasheet for AD7887: 2.7 V to 5.25 V, Micropower, 2-Channel, 125 kSPS, 12-Bit ADC in 8-Lead MSOP Data Sheet (Rev D)
Datasheet	ADI: Datasheet for ADXL103/ADXL203: Precision 1.7 g Single-/Dual-Axis i MEMS Accelerometer (Rev D)
Datasheet	ADI: Datasheet for AD8605/AD8606/AD8608: Precision, Low Noise, CMOS, Rail-to-Rail, Input/Output Operational Amplifiers (Rev L)
Application Note	ADI: Application Note (AN-1057) for Using an Accelerometer for Inclination Sensing
Application Note	ADI: Application Note (AN-688) for Phase and Frequency Response of iMEMS Accelerometers and Gyros

Design Elements

Type	Description
Schematics	ADI: Schematics for EVAL-CN0189-SDPZ Evaluation Board
Layout	ADI: Layout for EVAL-CN0189-SDPZ
BOM	ADI: Bill of Material (BOM) for EVAL-CN0189-SDPZ Evaluation Board
Reference Design	ADI: Reference Design for CN-0189 FMC-SDP Interposer & Evaluation Board / Xilinx KC705

Video

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Kit Features

Features of EVAL-CN0189-SDPZEVAL-CN0189-SDPZ evaluation board:

Incorporates a dual axis ADXL203ADXL203 accelerometer and the AD7887AD7887 12-bit successive approximation (SAR) ADC to create a dual axis tilt measurement system.
The ADXL203CEADXL203CE is a polysilicon surface micro machined sensor and signal conditioning circuit.
- High performance, single-/dual-axis accelerometer on a single IC chip
- 1 mg resolution at 60 Hz
- Low power: 700 μA at VS = 5 V (typical)
- High zero g bias stability
- High sensitivity accuracy
- X and Y axes aligned to within 0.1° (typical)
- Bandwidth adjustment with a single capacitor
- Single-supply operation
- 3500 g shock survival
The AD8608AD8608 quad op amp buffers, attenuates, and level shifts the ADXL203CEADXL203CE outputs
- AD8605AD8605/AD8608 features Unity gain stable
- Low offset voltage: 65 μV maximum
- Low input bias currents: 1 pA maximum
- Low noise: 8 nV/√Hz
- Wide bandwidth: 10 MHZ
- High open-loop gain: 1000 V/m
The AD7887AD7887 is configurable for either dual or single channel operation via the on-chip control register.
- Specified for VDD of 2.7 V to 5.25 V
- Flexible power/throughput rate management
- Shutdown mode: 1 μA max
- One or two single-ended inputs
- Serial interface: SPI®/QSPI™/MICROWIRE™/DSP compatible
The evaluation circuit maintains an accuracy of 1° over 90° and over temperature

Kit Contents

The Analog Devices EVAL-CN0189-SDPZEVAL-CN0189-SDPZ supplied with below contents:

EVAL-CN0189-SDPZEVAL-CN0189-SDPZ Evaluation Board

Tags: cn0189, eval-cn0189-sdpz, ad8605, eval-sdp-cb1z, adxl203, ad8608, ad7887, evaluation_board, analog_devices