ADIS16364

Preliminary Technical Data

Rev. PrA | Page 12 of 16

OPERATIONAL CONTROL

Global Commands

The GLOB_CMD register provides trigger bits for several useful

functions. Setting the assigned bit to 1 starts each operation,

which returns to the bit to 0 after completion. For example, set

GLOB_CMD[7] = 1 (DIN = 0xBE80) to execute a software

reset, which stops the sensor operation and runs the device

through its start-up sequence. This includes loading the control

registers with their respective flash memory locations prior to

producing new data. Reading the GLOB_CMD registers (DIN =

0x3E00) starts the burst mode read sequence.

Table 12. GLOB_CMD

Bits

Description

[15:8]

Not used

[7]

Software reset command

[6:5]

Not used

[4]

Precision autonull command

[3]

Flash update command

[2]

Auxiliary DAC data latch

[1]

Factory calibration restore command

[0]

Autonull command

Internal Sample Rate

The ADIS16364 performs best when the sample rate is set to the

factory default setting of 819.2 SPS. For applications that value

lower sample rates, the SMPL_PRD register controls the

ADIS16364 internal sample (see Table 13), and the following

relationship produces the sample rate:

Table 13. SMPL_PRD

Bit

Description

[15:8]

Not used

[7]

0 = 0.61035 ms, 1 = 18.921 ms

[6:0]

For example, set SMPL_PRD[7:0] = 0x0A (DIN = 0xB60A) for

an internal sample period of 6.7 ms (sample rate = 149 SPS).

For systems that value lower sample rates, in-system character-

ization can help determine performance trade-offs.

Power Management

Setting SMPL_PRD ≥ 0x0A also sets the sensor in low power

mode. In addition to sensor performance, this mode also affects

SPI data rates (see Table 2). Two sleep mode options are listed

in Table 14. Set SLP_CNT[8] = 1 (DIN = 0xBB01) to start the

indefinite sleep mode, which requires CS assertion (high to low),

reset, or power cycle to wake-up. Set SLP_CNT[7:0] = 0x64

(DIN = 0xBA64) to put the ADIS16364 to sleep for 100 sec, as

an example of the programmable sleep time option.

Table 14. SLP_CNT

Bit

Description

[15:9]

Not used

[8]

Indefinite sleep mode, set to 1

[7:0]

Programmable time bits, 0.5 sec/LSB

Digital Filtering

A programmable low-pass filtering provides additional

opportunity for noise reduction on the inertial sensor outputs.

This filter contains two cascaded averaging filters that provide a

Bartlett window, FIR filter response (see Figure 15).

SENS_AVG[2:0] controls the number of taps in each averaging

stage. For example, SENS_AVG[2:0] = 110 sets each stage tap to

64.

0

–20

–40

–60

–80

–100

–120

–140

0.001

0.01

0.1

1

FREQUENCY (

N = 2

N = 4

N = 16

N = 64

Figure 15. Bartlett Window FIR Frequency Response

(Phase = M Samples)

Dynamic Range

There are three dynamic range settings for the gyroscope:

±75°/sec, ±150°/sec, and ±300°/sec. The lower dynamic range

settings (±75°/sec and ±150°/sec) limit the minimum filter tap

sizes to maintain the resolution as the measurement range

decreases. The recommended order for programming the

SENS_AVG register is upper byte (sensitivity), followed by

lower byte (filtering). For example, set SENS_AVG[10:8] = 010

(DIN = 0xB902) for a measurement range to ±150°/sec.

Table 15. SENS_AVG

Bits

Value

Description

[15:11]

Not used

[10:8]

Measurement range (sensitivity) selection

100

±300°/sec (default condition)

010

±150°/sec, filter taps ≥ 4 (Bits[2:0] ≥ 0x02)

001

±75°/sec, filter taps ≥ 16 (Bits[2:0] ≥ 0x04)

[7:3]

Not used

[2:0]