Preliminary Technical Data

ADIS16364

Rev. PrA | Page 11 of 16

OUTPUT DATA REGISTERS

Figure 6 provides the positive measurement direction for each

inertial sensor (gyroscope and accelerometers). Table 9 provides

the configuration and scale factor for each output data register

in the ADIS16364. All inertial sensor outputs are 14 bits in

length and are in twos complement format, which means that

0x0000 is equal to 0 LSB, 0x0001 is equal to +1 LSB, and 0x3FFF

is equal to −1 LSB. The following is an example of how to

calculate the sensor measurement from the XGYRO_OUT:

()

()

/sec

60.3

1206

/sec

0.05

Rate

LSB

1206

0x04B6

16

11

256

4

0x04B6

0x33B4A

0x000

0x3B4A

XGYRO_OUT

°

−

=

−

×

°

=

−

=

−

+

×

+

×

−

=

−

=

−

=

6

Therefore, an XGYRO_OUT output of 0x3B4A corresponds to

a clockwise rotation about the z-axis (see Figure 6) of 60.3°/sec

when looking at the top of the package.

Table 9. Output Data Register Formats

Register

Bits

Format

Scale

SUPPLY_OUT

12

Binary, 5 V = 0x0814

2.42 mV

14

Twos complement

0.05°/sec

14

Twos complement

0.05°/sec

14

Twos complement

0.05°/sec

XACCL_OUT

14

Twos complement

1 mg

YACCL_OUT

14

Twos complement

1 mg

ZACCL_OUT

14

Twos complement

1 mg

12

Twos complement

0.14°C

12

Twos complement

0.14°C

12

Twos complement

0.14°C

AUX_ADC

12

Binary, 1 V = 0x04D9

0.81 mV

Each output data register uses the bit assignments shown in

Figure 13. 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 updates the registers with new data. The EA flag

indicates that one of the error flags in the DIAG_STAT register

(see Table 21) is active (true). The remaining 14 bits are for data.

MSB FOR 14-BIT OUTPUT

MSB FOR 12-BIT OUTPUT

ND EA

Figure 13. Output Register Bit Assignments

Auxiliary ADC

The AUX_ADC register provides access to the auxiliary ADC

input channel. The ADC is a 12-bit successive approximation

converter, which has an equivalent input circuit to the one

in Figure 14. The maximum input range is +3.3 V. The ESD

protection diodes can handle 10 mA without causing irreversible

damage. The switch on-resistance (R1) has a typical value of

100 Ω. The sampling capacitor, C2, has a typical value of 16 pF.

C2

C1

R1

VCC

D

D

Figure 14. Equivalent Analog Input Circuit

(Conversion Phase: Switch Open,

Track Phase: Switch Closed)

CALIBRATION

Manual Bias Calibration

The bias offset registers in Table 10 and Table 11 provide a manual

adjustment function for the output of each sensor. For example,

if XGYRO_OFF equals 0x1FF6, the XGYRO_OUT offset shifts

by −10 LSBs, or −0.125°/sec. The DIN command for the upper

byte is DIN = 0x9B1F; for the lower byte, DIN = 0x9AF6.

Table 10. XGYRO_OFF, YGYRO_OFF, ZGYRO_OFF

Bits

Description

[15:13]

Not used.

[12:0]

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

Typical adjustment range = ±50°/sec.

Table 11. XACCL_OFF, YACCL_OFF, ZACCL_OFF

Bits

Description

[15:12]

Not used.

[11:0]

Data bits, twos complement 1 mg/LSB.

Typical adjustment range = ±2 g.

Gyroscope Automatic Bias Null Calibration

Set GLOB_CMD[0] = 1 (DIN = 0xBE01) to execute this function,

which measures XGYRO_OUT and then loads XGYRO_OFF

with the opposite value to provide a quick bias calibration.

Then, all sensor data resets to 0, and the flash memory updates

automatically (50 ms). See Table 12.

Gyroscope Precision Automatic Bias Null Calibration

Set GLOB_CMD[4] = 1 (DIN = 0xBE10) to execute this

function, which takes the sensor offline for 30 sec while it

collects a set of XGYRO_OUT data and calculates a more

accurate bias correction factor. Once calculated, the correction

factor loads into XGYRO_OFF, all sensor data resets to 0, and

the flash memory updates automatically (50 ms). See Table 12.

Restoring Factory Calibration

Set GLOB_CMD[1] = 1 (DIN = 0xBE02) to execute this function,

which resets each user calibration register (see Table 10 and

Table 11) to 0x0000, resets all sensor data to 0, and auto-

matically updates the flash memory (50 ms). See Table 12.

Linear Acceleration Bias Compensation (Gyroscope)

Set MSC_CTRL[7] = 1 (DIN = 0xB486) to enable correction for

low frequency acceleration influences on gyroscope bias. Note

that the DIN sequence also preserves the factory default condi-

tion for the data ready function (see Table 17).