ADIS16400/ADIS16405

Rev. B | Page 12 of 20

0x3E00

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DON’T CARE

SUPPLY_OUT

XGYRO_OUT

AUX_ADC

123

13

YGYRO_OUT

ZGYRO_OUT

45

CS

SCLK

DIN

DOUT

Figure 12. Burst Mode Read Sequence

OUTPUT DATA REGISTERS

Figure 6 provides the positive measurement direction for each

gyroscope, accelerometer, and magnetometer. Table 9 provides

the configuration and scale factor for each output data register

in the ADIS16400/ADIS16405. All inertial sensor outputs are in

14-bit, 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:

XGYRO_OUT = 0x3B4A

0x000 − 0x3B4A = −0x04B6 = (4 × 256 + 11 × 16 + 6) −

0x04B6 = −1206 LSB

Rate = 0.05°/sec × (−1206) = −60.3°/sec

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

14

Binary, 5 V = 0x0814

2.418 mV

XGYRO_OUT1

14

Twos complement

0.05°/sec

YGYRO_OUT1

14

Twos complement

0.05°/sec

ZGYRO_OUT1

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

XMAGN_OUT

14

Twos complement

0.5 mgauss

YMAGN_OUT

14

Twos complement

0.5 mgauss

ZMAGN_OUT

14

Twos complement

0.5 mgauss

TEMP_OUT2

12

Twos complement

0.14°C

AUX_ADC

12

Binary, 1 V = 0x04D9

806 μV

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 23)

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 that has an equivalent input circuit to the one shown

in Figure 14. The maximum input is 3.3 V. The ESD protection

diodes can handle 10 mA without causing irreversible damage.

The on resistance (R1) of the switch 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, Table 11, and Table 12

(hard-iron correction for magnetometer) 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 LSB, 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

Default = 0x0000

[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

Default = 0x0000

[15:12]

Not used.

[11:0]

Data bits. Twos complement, 3.3 mg/LSB.

Typical adjustment range = ±6.75 g.

Table 12. XMAGN_HIF, YMAGN_HIF, ZMAGN_HIF

Bits

Description

Default = 0x0000

[15:14]

Not used.

[13:0]

Data bits. Twos complement, 0.5 mgauss/LSB.

Typical adjustment range = ±4 gauss.