Overview
The IMU8420 is a sophisticated MEMs sensor Inertial Measurement Unit platform with ten Degrees Of Freedom (DOF), onboard AVR32 processor (AT32UC3C2512) , real time clock and USB interface.  The IMU8420 combines a 3-Axis Accelerometer (ADXL345), 3-Axis Rate Gyro (L3G420D), 3-Axis Magnetometer (HMC5883) and a Barometer (BMP085) on a single PCB with processor and USB interface.  All four MEMs sensors are digital with either an SPI or I2C interface.

The real time clock allows sampled data to be time stamped in real time.  The external uSD (upto 32G storage)  allows sampled time stamped data to be stored in real time at user defined sample rates.

A turnkey real time data logging application developed using AVR Studio 6.1 is loaded into the AT32UC3C2512.  Complete source code for this application can be downloaded from our web site.  A rudimentary complementary filter is provided that outputs roll, pitch and yaw providing a AHRS capability.

The Accelerometer is capable of 4mG resolution over a +-16G range.   The Rate Gyro has three ranges - 250, 500 and 2000 deg/sec with a low range sensitivity of 17mdps.  The Magnetometer has eight ranges with a nominal resolution of 10mGauss.  The Barometer has an absolute accuracy of 8 meters and a resolution of 80cm.  Truly a unique combination of sensors. 

The onboard processor comes with DFU bootloader to allow field software upgrades.  The GPS module support Google Earths GPX file format allowing drag and drop files created by the datalogger directly into Google Earth.

Features
    o  10 Sensors integrated on one PCB
    o  3-Axis Accelerometer ADXL345
    o  3-Axis Rate Gyro L3G4200D
    o  3-Axis Magnetometer HMC5883
    o  Barometer BMP085 with 8m accuracy and 0.8m resolution
    o  All digital sensors
    o  AT32UC3C2512 processor with DFU bootloader
    o  USB 2.0 interface
    o  Optional double AA battery holder (switch selectable with USB interface)
    o  Example application included for rapid application development
    o  1.8-3.6VDC power input 
    o  Extremely Small form factor (1.34x2.34 in)
 

Description
The IMU84200 is an extremely compact embedded IMU sensor platform for mobile data acquisition, instrumentation and remote monitoring applications.  The IMU8420 is an all digital implementation with no requirement for AD interfacing.   

Processor and Communication Interfaces
The IMU842 uses an 32 bit AVR processor with 512K of flash - AT32UC3C2512.  An onboard USB 2.0 interface supports high speed serial communication with the desktop.  A real time clock crystal attached to the ATmega1284P allows real time stamping of logged data.  The processor has two UARTs - one for communicating with GPS and Wireless adapters - the other available for use by other devices.  An SPI interface, 8 channel analog interface and digital IO is also available to communicate with other devices.

3-Axis Accelerometer
The 3-Axis accelerometer is an Analog Devices ADXL345.  The ADXL345 has four programmable acceleration ranges- 2G, 4G, 8G and 16G set by the ATmega644.   The ADXL345 operates from 2.2 to 3.6Vdrawing 140uA so the Wasp should not be powered higher than 3.6V when the accelerometer is installed.  The accelerometer has a sensitivity of 4mG over the full 16G range, a bandwidth of 3500Hz (XY)  150Hz (Z), non-linearity less than 1% and a cross-axis sensitivity less than 1%.

The accelerometer is oriented with the X+ on the long axis of the PCB toward Port A connector J1, Y+ on the short axis of the PCB toward Port B connector J2 and Z+ pointing up out of the board.

3-Axis Rate Gyro
The 3-Axis Rate Gyro is an STMicroelectronics L3G4200D.  The L3G4200D has three programmable gyro ranges- 250, 500 and 200dps set by the ATmega644.   The L3G4200D operates from 2.2 to 3.6Vdrawing 6mA so the Wasp should not be powered higher than 3.6V when the accelerometer is installed.  The Gyro has a sensitivity of 17mdps (250dps setting),  a bandwidth of 350Hz (XY)  150Hz (Z), non-linearity less than 1% and a cross-axis sensitivity less than 5%.

3-Axis Magnetometer
The 3-Axis Magnetometer is a Honeywell HMC5883.  The HMC5883 has eight programmable gauss ranges- 0.88G, 1.3G, 4G and 8.1G set by the ATmega644.   The HMC5883 operates from 2.2 to 3.6Vdrawing 100uA so the Wasp should not be powered higher than 3.6V when the accelerometer is installed.  The Magnetometer has a sensitivity of 2mG (1.3g setting),  a bandwidth of 350Hz (XY)  150Hz (Z), non-linearity less than 1% and a cross-axis sensitivity less than 5%.

Power Management, Lithium Battery and Optional Battery Holder
The platform supports several battery options.  An optional lithium battery is available.  An integrated charging circuit is already on the board and is designed to support a number of lithium battery capacities.   An optional battery holder allows the platform to be powered by inexpensive.  An optional high voltage circuit (not mounted) allows the platform to be powered by 12V or 24V systems.

Software Tools
Source code examples to setup and configure the three different MEMs sensors is provided as part of the IMU8420 Data Logger Application V1.03.  The application example is programmed in C using a Atmel's AVR Studio V6.1.  Check the SOC Robotics web site for program examples and the AVR Studio project file. 

The IMU842 AT32UC3C2512 processor comes with an DFU bootloader allowing field upgrades.  The DFU bootloader is activated by holding a specific interface pin low during power up.  All the necessary programming tools can be downloaded from Atmel's web site.  The Data Logger Project file has the necessary batch files to simplify the re-flashing processor.

Related Products
The following products can be used with the IMU8420:      

 ZB1    Zigbee Wireless Adapter.

  USB10Z    Zigbee wireless with USB10 compatible USB 2.0 interface for desktop link to IMU8420.

    GP1    GPS Module with MT3329

                                                   

Downloads/Revisions
The following technical Manuals, datasheets and software downloads are available.  Version 1.03b is the latest release.  See the release notes on V1.02 and V1.03 for a detailed description of current features.  A new version of the EKF is under development along with a new desktop communications and configuration utility.  Source code is available upon request.

Technical Documentation:
     IMU8420 Technical Manual                      IMU8420 Technical Manual.pdf
     IMU8420  AT32UC3C2512 Processor     AT32UC3C2512 Processor Datasheet.pdf
     IMU8420 V1.02 Release Notes                  IMU8420 V1.02 Release Notes.pdf
     IMU8420 V1.03 Release Notes                  IMU8420 V1.03 Release Notes.pdf
     IMU8420 V1.03b Release Notes                IMU8420 V1.03b Release Notes.pdf
     IMU GNUPLOT Utility                                IMU GNUPLOT Utility.pdf

Project Release Versions:
      IMU8420 Data Logger  V1.03b               IMU8420 Data Logger V1.03b.zip
      AVR32 Windows 8 Signed USB CDC inf               AVR32 Win8 CDC inf.zip
      IMU8420 Data Logger  V1.03b hex       IMU8420 Data Logger V1.03b.hex

3D Enclosure Designs:
      IMU8420 3D Case Designs                 IMU8420 3D Case Design.zip

Sensor Datasheets:
      ADXL345 Datasheet                                ADXL345 Datasheet.pdf
      L3G4200D Datasheet                              L3G4200D Datasheet.pdf
      HMC5883L Datasheet                             HMC5883L Datasheet.pdf
      BMP085 Datasheet                                   BMP085 Datasheet.pdf