ADIS16300

Rev. 0 | Page 11 of 16

()

()

/sec

60.3

1206

/sec

0.05

Rate

LSB

1206

0x04B6

6

16

11

256

4

0x04B6

0x33B4A

0x000

°

−

=

−

×

°

=

−

=

−

+

×

+

×

−

=

−

=

−

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 ADIS16300. 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 GYRO_OUT:

0x3B4A

GYRO_OUT

=

Therefore, a GYRO_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

GYRO_OUT1

14

Twos complement

0.05°/sec

XACCL_OUT

14

Twos complement

0.6 mg

YACCL_OUT

14

Twos complement

0.6 mg

ZACCL_OUT

14

Twos complement

0.6 mg

TEMP_OUT

12

Twos complement

25°C = 0x0000

0.14°C

ROLL_OUT

13

Twos complement

0.044°

PITCH_OUT

13

Twos complement

0.044°

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

Inclinometers

The ROLL_OUT and PITCH_OUT registers provide a tilt angle

calculation, based on the accelerometers. The zero reference is

the point at which the z-axis faces gravity for a north-east-down

(NED) configuration.

⎟

⎠

⎞

⎜⎜

⎝

⎛

+

−

=

⎟

⎠

⎜

⎝

φ

φ

cos

_

)

sin(

_

_

tan

_

_

x

OUT

ZACCL

x

OUT

YACCL

OUT

XACCL

a

OUT

PITCH

OUT

ZACCL

=

⎟

⎞

⎜

⎛

=

φ

_

tan

_

OUT

YACCL

a

OUT

ROLL

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.

V

C2

C1

R1

CC

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 GYRO_OFF equals 0x1FF6, the GYRO_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. GYRO_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 0.6 mg/LSB.

Typical adjustment range = ±1.2 g.

Gyroscope Automatic Bias Null Calibration

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

which measures GYRO_OUT and then loads GYRO_OFF with

the opposite value to provide a quick bias calibration. Then, all

sensor data resets to zero, 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 seconds while it collects a

set of GYRO_OUT data and calculates a more accurate bias

correction factor. Once calculated, the correction factor loads

into GYRO_OFF, all sensor data resets to zero, and the flash

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