ADIS16365

Preliminary Technical Data

Rev. PrA | Page 12 of 20

OUTPUT DATA REGISTERS

Table 8 provides the data configuration for each output data

register in the ADIS16365. Starting with the MSB of the upper

byte, each output data register has the following bit sequence:

new data (ND) flag, error/alarm (EA) flag, followed by 14 data

bits. The data bits are LSB-justified and, in the case of the 12-bit

data formats, the remaining two bits are not used. The ND flag

indicates that unread data resides in the output data registers.

This flag clears and returns to 0 during an output register read

sequence. It returns to 1 after the next internal sample update

cycle completes. The EA flag indicates an error condition. The

STATUS register contains all of the error flags and provides the

ability to investigate the root cause.

Table 8. Output Data Register Formats

Register

Bits

Format

Scale

SUPPLY_OUT1

12

Binary, +5V = 0x

2.418 mV

XGYRO_OUT2

14

Twos complement

0.05°/sec

YGYRO_OUT2

14

Twos complement

0.05°/sec

ZGYRO_OUT2

14

Twos complement

0.05°/sec

XACCL_OUT

14

Twos complement

3.33 mg

YACCL_OUT

14

Twos complement

3.33 mg

ZACCL_OUT

14

Twos complement

3.33 mg

XTEMP_OUT3

12

Binary, 25°C = 0x04FE

0.1453°C

YTEMP_OUT3

12

Binary, 25°C = 0x04FE

0.1453°C

ZTEMP_OUT3

12

Binary, 25°C = 0x04FE

0.1453°C

AUX_ADC

12

Binary = 0x04FE

0.8059 mV

CALIBRATION

Manual Bias Calibration

The bias offset registers in Table 9 and Table 10 provide a

manual adjustment function for each sensor’s output. For

example, if an output offset of 0.125°/sec is observed in the Z-

axis gyroscope, the ZGYRO_OFF register provides the

calibration factor necessary to improve the accuracy. Using the

sensitivity of 0.0125°/sec, an adjustment of −10 LSBs is

required. The twos complement, hexadecimal code of −10 LSBs

is 0x1FF6. See Table 11 for the DIN command.

Table 9. X,Y,ZGYRO_OFF Register Bits

Bits

Description

(Default = 0x0000)

[15:13]

Not used.

[12:0]

Data bits. Twos complement, 0.0125°/sec per LSB.

Typical adjustment range = ±50°/sec.

Table 10. X,Y,ZACCL_OFF Register Bits

Bits

Description

(Default = 0x0000)

[15:12]

Not used.

[11:0]

Data bits, Twos complement 3.3 mg/LSB.

Typical adjustment range = ±6 g.

Automatic Bias Null Calibration

This single-command calibration function is in the

COMMAND register and measures all three-gyroscope output

registers, then loads the three bias correction registers with

values that return their outputs to zero (null). See Table 11 for

the DIN command.

Precision Automatic Bias Null Calibration

This single-command calibration function is in the COMMAND

register and incorporates a 30-second average of all three gyro-

scope output registers, then loads the three bias correction

registers with values that return their outputs to zero (null). For

optimal calibration accuracy, the device should be stable (no

motion) for this entire period. Once it has started, a reset is the

only way to stop it prematurely, if required. See Table 11 for the

DIN command.

Restoring Factory Calibration

This single command is in the COMMAND register and restores

the factory calibration by writing 0x0000 into each bias offset

register listed in Table 9 and Table 10. This command also flushes

all of the data from the digital filter taps. See Table 11 for the

DIN command.

Linear Acceleration Bias Compensation (Gyroscopes)

This function enables compensation for low-frequency

acceleration influences on gyroscope bias behavior, using the

MSC_CTRL register. See Table 11 for the DIN command.

Linear Acceleration Origin Alignment

This function enables origin alignment for the accelerometers

to the point of percussion (see Figure 6), using the MSC_CTRL

register. See Table 11 for the DIN command.

Table 11. Calibration Commands

Calibration Function

DIN Word(s)

Adjust Z-Axis Gyroscope Bias by −0.125°/sec:

Write 0x1F to 0x1F

Write 0xF6 to 0x1E (ZGYRO_OFF)

0x9E1F

0x9FF6

Automatic Bias Null:

Write 0x01 to 0x3E (COMMAND)

0xBE01

Precision Automatic Bias Null:

Write 0x10 to 0x3E (COMMAND)

0xBE10

Factory Calibration Restore:

Write 0x02 to 0x3E (COMMAND)

0xBE02

Enable Linear Acceleration Bias

Compensation for the Gyroscopes:

Write 0x86 to 0x34 (MSC_CTRL)

0xB486

Enable Origin Alignment for the

Accelerometer Sensors:

Write 0x46 to 0x34 (MSC_CTRL)

0xB446

The last two entries assume factory default conditions for the

MSC_CTRL register. The contents may vary, depending on the

other MSC_CTRL settings. See Table 17 for further description

of each bit in this register.