Ten Degrees of Freedom MEMS Inertial Sensor with Dynamic Orientation Outputs Silicon Anomaly ADIS16480 This anomaly list describes the known bugs, anomalies, and workarounds for the ADIS16480. Analog Devices, Inc., is committed, through future silicon revisions, to continuously improve silicon functionality. Analog Devices tries to ensure that these future silicon revisions remain compatible with your present software/systems by implementing the recommended workarounds outlined here. FUNCTIONALITY ISSUES Table 1. Incorrect Scale Factors for the x DELTANG OUT Registers and the x DELTANG LOW Registers er001 Background The ADIS16480 provides delta angle registers, which contain sample-to-sample angle displacement estimates for all three axes. The x DELTANG OUT registers provide the upper 16 bits, and the x DELTANG LOW registers provide the lower 16 bits. 15 The x DELTANG OUT registers typically provide a scale factor of 720 2 degrees per LSB, and the x DELTANG LOW 31 registers provide additional resolution (720 2 degrees per LSB). On units that have Firmware Revision 2.01 (or earlier), the delta angle registers do not have the same scale factors as those Issue 15 listed in the ADIS16480 data sheet. For these units, the scale factors are 274 2 degrees per LSB for x DELTANG OUT and 31 274 2 degrees per LSB for x DELTANG LOW. 15 31 Workaround Use 274 2 degrees per LSB for the x DELTANG OUT scale factor and 274 2 degrees per LSB for the x DELTANG LOW scale factor. Use the FIRM REV register to determine the firmware revision of a unit. For example, FIRM REV = 0x0201 equates to a Firmware Revision 2.01. Related Issues None. Table 2. Incorrect Scale Factors for the x DELTVEL OUT Registers and the x DELTVEL LOW Registers er002 Background The ADIS16480 provides delta velocity registers, which contain sample-to-sample velocity estimates for all three axes. The x DELTVEL OUT registers provide the upper 16 bits, and the x DELTVEL LOW registers provide the lower 16 bits. The 15 x DELTVEL OUT registers typically provide a scale factor of 200 2 m/sec per LSB, and the x DELTVEL LOW registers 31 provide additional resolution (200 2 m/sec per LSB). The ADIS16480 (Rev. A) data sheet incorrectly documents these 15 31 scale factors as 160 2 and 160 2 , respectively these errors are being addressed in Rev. B of the data sheet. Issue On units that have Firmware Revision 2.01 (or earlier), the delta velocity registers do not have the same scale factors as 15 those listed in the ADIS16480 data sheet. For these units, the scale factors are 97.65 2 m/sec per LSB for x DELTVEL OUT 31 and 97.65 2 m/sec per LSB for x DELTVEL LOW. 15 31 m/sec per LSB for the x DELTVEL OUT scale factor and 97.65 2 m/sec per LSB for the x DELTVEL LOW Workaround Use 97.65 2 scale factor. Use the FIRM REV register to determine the firmware revision of a unit. For example, FIRM REV = 0x0201 equates to a Firmware Revision 2.01. Related Issues None. Table 3. Inaccurate TEMP OUT Readings er003 Background The TEMP OUT register provides the internal temperature measurement, which serves as an input to the inertial calibration outputs and also provides a variable that enables users to monitor relative temperature changes inside the unit. Issue On units that have Firmware Revision 2.01 (or earlier), the TEMP OUT bias error is 10C, and the scale factor is approximately 5% lower than the scale factor reflected in the ADIS16480 data sheet. Workaround Use devices that have Firmware Revision 2.02 or later to benefit from the improvement in the TEMP OUT accuracy. For specific, in-application accuracy, users may want to consider their own calibration process because attachment, airflow, and other mechanical variables can affect the TEMP OUT relationship with ambient temperature conditions. Use the FIRM REV register to determine the firmware revision of a unit. For example, FIRM REV = 0x0201 equates to a FirmwareRevision 2.01. Related Issues None. Rev. 0 Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 2014 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Technical Support www.analog.com ADIS16480 Silicon Anomaly Table 4. Incorrect Output Data String After Writing to the FNCTIO CTRL Register er004 Background The FNCTIO CTRL register provides user configuration control for the digital I/O pins, and the TEMP OUT register provides the internal temperature measurement, which serves as an input to the inertial calibration outputs. Issue On units that have Firmware Revision 2.01 (or earlier), a write to the FNCTIO CTRL register causes the TEMP OUT variable to contain an incorrect value for 120 samples. Because this is an input to the calibration function for the gyroscopes and accelerometers, this issue causes the appearance of a discrete bias change between Sample 120 and Sample 121. Workaround When using units that have Firmware Revision 2.01 (or earlier), ignore the first 120 samples of the output registers after writing to the FNCTIO CTRL register. Use the FIRM REV register to determine the firmware revision of a unit. For example, FIRM REV = 0x0201 equates to a firmware revision of 2.01. Related Issues None. Table 5. Incorrect Offset and Scale Correction Order er005 Background Each accelerometer and gyroscope has unique user configurable offset and scale correction registers. For instance, on the x-axis gyroscope, the XG BIAS HIGH and XG BIAS LOW registers combine to provide the 32-bit, twos complement bias (offset) correction factor, and the X GYRO SCALE register provides the scale correction function. The proper order of applying these correction factors is bias correction first and scale correction second. Issue On units that have Firmware Revision 2.01 (or earlier), the order of application is reversed, and the ADIS16480 applies the scale correction value first, followed by the offset value. Workaround When using units that have firmware Revision 2.01 or earlier, if this function is part of the system-level calibration processes, note this difference. Use the FIRM REV register to determine the firmware revision of a unit. For example, FIRM REV = 0x0201 equates to a Firmware Revision 2.01. Related Issues None. Table 6. Factory Restore Command in GLOB CMD Not Working Properly er006 Background GLOB CMD 6 provides a factory restore function that enables users to reset all user configurable calibration registers to 0x0000 (factory default). To activate this function, turn to Page 3 by setting DIN = 0x8003, and then set GLOB CMD 6 = 1 by writing the following two 16-bit commands to the DIN line: 0x8240 and 0x8300. Issue On units that have Firmware Revision 2.03 (or earlier), setting GLOB CMD 6 = 1 does not reset all calibration registers. Workaround When using units that have Firmware Revision 2.03 (or earlier), write 0x0000 to each individual calibration register. Use the FIRM REV register to determine the firmware revision of a unit. For example, FIRM REV = 0x0203 equates to a Firmware Revision 2.03. Related Issues None. Table 7. EKF Setting Time and Accuracy Affected by Accidental Writes to Hidden Register er007 Background In the ADIS16480 data sheet, Address 0x0E on Page 3 is a reserved location. Although this location contains a valid user register for other products in this same family, it is not accessible through the serial peripheral interface (SPI) for users. On units that have Firmware Revision 2.04 and earlier, this location is not write protected and can influence the extended Issue Kalman filter (EKF) operation. Workaround On Page 3, write 0x04 to Address 0x0E and write 0x07 to Address 0x0F to restore proper EKF settling and operation. Note that the factory default is 0x070A for all devices that have Firmware Revision 2.04 and earlier. If this setting is providing proper service for a particular application, there is no need to change it. Ensure that this location does not experience any other write commands. The impact of moving from 0x070A to 0x0704 is that the EKF settling time is reduced from ~26 sec to ~416 ms. Related Issues None. Rev. 0 Page 2 of 4