I've been having a number of problems attempting calibration of the ADIS16265 with regards to the RevD datasheet.
First, I have been unable to located an application note that describes the correct implementation of the autonull feature. Do you have a programmers application note somewhere that you can share.
Secondly, the datasheet (rev D) description for biasing the gyro is clearly in error. I have provided it below:
1. Apply 5 V and wait 10 sec.
2. Set SENS_AVG[10:8] = 001 (DIN = 0xB901).
3. Set GLOB_CMD = 1 (DIN = 0xBE02).
4. Collect GYRO_OUT data for 150 sec at a sample rate of 256 SPS.
5. Average data record.
6. Round to the nearest integer.
7. Multiply by −1.
8. Write to GYRO_OFF.
9. Update flash.
Set GLOB_CMD = 1 (DIN = 0xBE08).
The most obvious error I see is that step 3 performs a factory calibration restore command thereby nullifying step 2. You probably intended step 2 follow step 3. Also, no mention that the scaling (1,2 or 4) must be used when writing the offset based on the measurement range setting.
Third: What is one expected to do if the gyro bias exceeds 2048*(0.018315°/sec), as is the case with one of my three ADIS16265 mems gyros? The gyro in question has a drift bias of 2310*(0.018315°/sec). Am I forced to adjust the scalar to bring it into range of the max offset, and then factor in the adjusted gyro rate?