ADIS16400SLASHPCBZ datasheet(15/20 Pages) AD

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ADIS16400/ADIS16405

Rev. B | Page 15 of 20

Auxiliary DAC

The 12-bit AUX_DAC line can drive its output to within 5 mV

of the ground reference when it is not sinking current. As the

output approaches 0 V, the linearity begins to degrade (~100 LSB

beginning point). As the sink current increases, the nonlinear

range increases. The DAC latch command moves the values of

the AUX_DAC register into the DAC input register, enabling

both bytes to take effect at the same time.

Table 20. AUX_DAC

Bits

Description

Default = 0x0000

[15:12]

Not used.

[11:0]

Data bits. Scale factor = 0.8059 mV/code,

offset binary format, 0 V = 0 codes.

Table 21. Setting AUX_DAC = 1 V

DIN

Description

0xB0D9

AUX_DAC[7:0] = 0xD9 (217 LSB).

0xB104

AUX_DAC[15:8] = 0x04 (1024 LSB).

0xBE04

GLOB_CMD[2] = 1.

Move values into the DAC input register, resulting in

a 1 V output level.

DIAGNOSTICS

Self-Test

The self-test function offers the opportunity to verify the

mechanical integrity of each MEMS sensor. It applies an

electrostatic force to each sensor element, which results in

mechanical displacement that simulates a response to actual

motion. Table 1 lists the expected response for each sensor,

which provides pass/fail criteria. Set MSC_CTRL[10] = 1 (DIN

= 0xB504) to run the internal self-test routine, which exercises

all inertial sensors, measures each response, makes pass/fail

decisions, and reports them to error flags in the DIAG_STAT

routine. MSC_CTRL[9:8] (DIN = 0xB502 or 0xB501) provide

manual control over the self-test function. Table 22 shows an

example test flow for using this option to check the x-axis

gyroscope. Zero motion provides results that are more reliable.

The settings in Table 22 are flexible and provide opportunity for

optimization around speed and noise influence. For example,

using fewer filtering taps decreases delay times but increases the

opportunity for noise influence.

Memory Test

Setting MSC_CTRL[11] = 1 (DIN = 0xB508) performs a

checksum verification of the flash memory locations. The

pass/fail result loads into the DIAG_STAT[6] register.

Status

The error flags provide indicator functions for common system-

level issues. All of the flags clear (set to 0) after each DIAG_STAT

returns to 1 during the next sample cycle. DIAG_STAT[1:0]

does not require a read of this register to return to 0.

Table 22. Manual Self-Test Example Sequence

DIN

Description

0xB601

SMPL_PRD[7:0] = 0x01, sample rate = 819.2 SPS.

0xB904

SENS_AVG[15:8] = 0x04, gyroscope range = ±300°/sec.

0xB802

SENS_AVG[7:0] = 0x02, four-tap averaging filter.

Delay = 50 ms.

0x0400

Read XGYRO_OUT.

0xB502

MSC_CTRL[9] = 1, gyroscope negative self-test.

Delay = 50 ms.

0x0400

Read XGYRO_OUT.

Calculate the positive change from the first reading to

the second reading of XGYRO_OUT, and check to

make sure the change is within the positive self-test

response range specified in Table 1.

0xB501

MSC_CTRL[9:8] = 01, gyroscope/accelerometer

positive self-test.

Delay = 50 ms.

0x0400

Read XGYRO_OUT.

Calculate the negative change from the first reading

to the third reading of XGYRO_OUT, and check to

make sure the change is within the positive self-test

response range specified in Table 1

0xB500

MSC_CTRL[15:8] = 0x00.

Table 23. DIAG_STAT Bit Descriptions

Bit

Description

[15]

Z-axis accelerometer self-test failure (1 = fail, 0 = pass)

[14]

Y-axis accelerometer self-test failure (1 = fail, 0 = pass)

[13]

X-axis accelerometer self-test failure (1 = fail, 0 = pass)

[12]

Z-axis gyroscope self-test failure (1 = fail, 0 = pass)

[11]

Y-axis gyroscope self-test failure (1 = fail, 0 = pass)

[10]

X-axis gyroscope self-test failure (1 = fail, 0 = pass)

[9]

Alarm 2 status (1 = active, 0 = inactive)

[8]

Alarm 1 status (1 = active, 0 = inactive)

[7]

Not used

[6]

Flash test, checksum flag (1 = fail, 0 = pass)

[5]

Self-test diagnostic error flag (1 = fail, 0 = pass)

[4]

Sensor overrange (1 = fail, 0 = pass)

[3]

SPI communication failure (1 = fail, 0 = pass)

[2]

Flash update failure (1 = fail, 0 = pass)

[1]

Power supply above 5.25 V

(1 = power supply ≥ 5.25 V, 0 = power supply ≤ 5.25 V)

[0]

Power supply below 4.75 V

(1 = power supply ≤ 4.75 V, 0 = power supply ≥ 4.75 V)

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