ADIS16250

Rev. 0 | Page 19 of 20

Alarms

The ADIS16250 provides two independent alarm options for

event detection. Event detections occur when output register

data meets the configured conditions. Configuration options are:

•

All output data registers are available for monitoring

as the source data

•

The source data can be filtered or unfiltered

•

Comparisons can be static or dynamic (rate of change)

•

The threshold levels and times are configurable

•

Comparison can be greater than or less than

The ALM_MAG1 register and the ALM_MAG2 register both

establish the threshold level for detecting events. They take on the

format of the source data and provide a bit for establishing the

greater than/less than comparison direction. When making

dynamic comparisons, the ALM_SMPL1 register and the

ALM_SMPL2 register establish the number of averages taken for

the source data as a reference for comparison. In this configuration,

each subsequent source data sample is subtracted from the previous

one, establishing an instantaneous delta. The ALM_CTRL register

controls the source data selection, static/dynamic selection, filtering

selection, and digital I/O usage for the alarms.

The rate of change calculation is

)

?

or

(

MSB

ALM_MAG1/2

to

according

with

Compare

alarm

change

of

Rate

)

(

)

1

(

1

with

compared

be

factor to

ALM_MAG1/2

in

comparison

for

magnitude

data

output

sampled

)

(

2

ALM_SMPL1/

in

samples

of

number

DS

N

1

n

<

>

⇒

−

+

=

=

=

=

=

∑

=

C

C

DS

C

C

C

C

DS

M

Y

n

y

n

y

N

Y

M

Y

M

n

y

N

Table 31. ALM_MAG1 Register Definition

Address

Default

Format

Access

0x21, 0x20

0x0000

N/A

R/W

Table 32. ALM_MAG1 Bit Designations

Bit

Description

15

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

14

Not used

13:0

Data bits: format matches source data format

Table 33. ALM_SMPL1 Register Definition

Address

Default

Format

Access

0x25, 0x24

0x0000

Binary

R/W

Table 34. ALM_SMPL1 Bit Designations

Bit

Description

15:8

Not used

7:0

Data bits

Table 35. ALM_MAG2 Register Definition

Address

Default

Format

Access

0x23, 0x22

0x0000

N/A

R/W

Table 36. ALM_MAG2 Bit Designations

Bit

Description

15

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

14

Not used

13:0

Data bits: format matches source data format

Table 37. ALM_SMPL2 Register Definition

Address

Default

Format

Access

0x27, 0x26

0x0000

Binary

R/W

Table 38. ALM_SMPL2 Bit Designations

Bit

Description

15:8

Not used

7:0

Data bits

Table 39. ALM_CTRL Register Definition

Address

Default

Format

Access

0x29, 0x28

0x0000

N/A

R/W

Table 40. ALM_CTRL Bit Designations

Bit

Value

Description

15

Rate of change (ROC) enable for alarm 2

1 = rate of change, 0 = static level

14:12

Alarm 2 source selection

000

Disable

001

Power supply output

010

Gyroscope output

011

Inactive

100

Inactive

101

Auxiliary ADC output

110

Temperature sensor output

111

Inactive

11

Rate of change (ROC) enable for alarm 1

1 = rate of change, 0 = static level

10:8

Alarm 1 source selection

000

Disable

001

Power supply output

010

Gyroscope output

011

Inactive

100

Inactive

101

Auxiliary ADC output

110

Temperature sensor output

111

Inactive

7:5

Not used

4

Filtered data comparison

1 = filtered data, 0 = unfiltered data

3

Not used

2

Alarm output enable

1 = enabled, 0 = disabled

1

Alarm output polarity

1 = active high, 0 = active low

0

Alarm output line select

1 = DIO1, 0 = DIO0