ADIS16209

Preliminary Technical Data

Rev. PrA | Page 14 of 16

contents of the output data registers and loads the equal but

opposite number into the offset calibration registers. The

accuracy of this operation depends on zero force, zero motion,

and optimal noise management during the measurement (see

the Digital Filtering section). The factory calibration restore sets

the offset null registers (XACCL_NULL, for example) back to

their default values.

CALIBRATION REGISTERS

The ADIS16209 incorporates an extensive factory calibration

and provides precision acceleration, incline, and rotational

position data. For systems that require on-site calibration,

user-programmable offset adjustment registers are available.

Table 16 provides the bit assignments for the following user-

programmable calibration registers: XACCL_NULL and

YACCL_NULL. Table 17 provides the bit assignments for

the following user-programmable calibration registers:

XINCL_NULL, YINCL_NULL, and ROT_NULL.

Table 16. Acceleration Offset Register Bit Designations

Bit

Description

(Default = 0x0000)

15:12

Not used

11:0

Data bits, twos complement, sensitivity = 0.244 mg/LSB

Table 17. Incline/Rotation Offset Register Bit Designations

Bit

Description

(Default = 0x0000)

15:14

Not used

13:0

Data bits, twos complement, sensitivity = 0.025°/LSB

ALARM REGISTERS

The alarm function provides monitoring for two independent

conditions. The ALM_CTRL register provides control inputs

for data source, data filtering (prior to comparison), static/

dynamic, and output indicator configurations. The ALM_MAGx

registers establish the trigger threshold and polarity configura-

tions. The ALM_SMPLx registers provide the numbers of

samples to use in the dynamic, rate-of-change configuration.

The rate-of-change calculation is

?

or

is

)

(

)

1

(

1

C

C

DS

N

n

DS

C

M

Y

Alarm

n

y

n

y

N

Y

<

>

⇒

⇒

−

+

=

∑

=1

where:

y(n) is the sampled output data.

> or < is determined by the MSB in ALM_MAGx.

Table 18. ALM_MAG1/ALM_MAG2 Bit Designations

Bit

Description

(Default = 0x0000)

15

Comparison polarity: 1 = greater than, 0 = less than

14

Not used

13:0

Data bits, matches format of trigger source selection

Table 19. ALM_SMPL1/ALM_SMPL2 Bit Designations

Bit

Description

(Default = 0x0001)

15:8

Not used

7:0

Data bits: number of samples (both 0x00 and 0x01 = 1)

Table 20. ALM_CTRL Bit Descriptions

Bit

Value

Description

(Default = 0x0000)

15

Alarm 2 rate of change control: 1 = enabled

14:12

Trigger source, Alarm 2

000

Disabled

001

Power supply

010

X-acceleration

011

Y-acceleration

100

Temperature sensor

101

X-axis incline angle

110

Y-axis incline angle

111

Rotational position

11

Alarm 1: rate-of-change control, 1 = enabled

10:8

Trigger source, Alarm 1, same as bits 14:12

7:6

Not used

5

Alarm 2 filter: 1 = filtered data, 0 = no filter

4

Alarm 1 filter: 1 = filtered data, 0 = no filter

3

Not used

2

Alarm indicator, using DIO1/DIO2: 1 = enabled

1

Alarm indicator polarity: 1 = active high

0

Alarm indicator line select: 1 = DIO2, 0 = DIO1

Status

The STATUS register provides a series of error flags, which

provide indicator functions for common system-level issues. All

of the flags clear (set to 0) after each STATUS register read

cycle. If an error condition remains, then the error flag returns

to 1 during the next sample cycle.

Table 21. STATUS Bit Descriptions

Bit

Description

(Default = 0x0000)

15:10

Not used

9

Alarm 2 status

1 = active, 0 = inactive

8

Alarm 1 status

1 = active, 0 = inactive

7:6

Not used

5

Self-test diagnostic error flag

1 = error condition, 0 = normal operation

4

Not used

3

SPI communications failure

1 = error condition, 0 = normal operation

2

Flash update failed

1 = error condition, 0 = normal operation

1

Power supply above 3.625 V

1 = >3.625 V, 0 = <2.975 V (normal)

0

Power supply below 2.975 V

1 = <2.975 V, 0 = >2.975 V (normal)