ADIS16204

Rev. 0 | Page 19 of 24

Table 29. Alarm and Event Capture Configuration Registers

Register

Parameter/Function

Default Setting

ALM_CTRL

Alarm trigger source

None

ALM_CTRL

Capture buffer triggers

Disabled

ALM_CTRL

Digital alarm output

Disabled

ALM_MAG1/

ALM_MAG 2

Alarm trigger levels

0

ALM_MAG1/

ALM_MAG 2

Alarm trigger directions

Less than

CAPT_CFG

Capture data sources

1: X acceleration

2: Y acceleration

CAPT_CFG

Capture buffer size

1024 samples

CAPT_CFG

Pretrigger data size

128 samples

COMMAND

Reset capture pointer

N/A

COMMAND

Clear capture buffer

N/A

COMMAND

Clear capture flash

N/A

COMMAND

Clear buffer full flag

N/A

COMMAND

Save captured data to

nonvolatile flash

N/A

MSC_CTRL

Autosave captured

data to nonvolatile flash

Disabled

SMPL_PRD

Sample rate

4096 SPS

Table 30. ALM_CTRL Register Definition

Address

Default

Format

Access

0x29, 0x28

0x0000

N/A

R/W

Table 31. ALM_CTRL Bit Descriptions

Bit

Value

Description

15:12

Trigger source selection, Alarm 2

0000

Disable

0001

Power supply

0010

X-acceleration

0011

Y-acceleration

0100

Auxiliary ADC

0101

Temperature sensor

1000

XY RSS acceleration

11:8

Trigger source selection, Alarm 1 (See Alarm2)

7

Not used

6

Capture trigger activation, Alarm 2

1 = enabled, 0 = disabled

5

Not used

4

Capture trigger activation, Alarm 1

1 = enabled, 0 = disabled

3

Not used

2

Alarm indicator, using DIO1/2

1 = enabled, 0 = disabled

1

Alarm indicator polarity

1 = active high, 0 = active low

0

Alarm indicator line selection

1 = DIO2, 0 = DIO1

Table 32. ALM_MAG1 Register Definition

Address

Default

Format

Access

0x21, 0x20

0x0000

N/A

R/W

Table 33. ALM_MAG2 Register Definition

Address

Default

Format

Access

0x23, 0x22

0x0000

N/A

R/W

Table 34. ALM_MAG1/ALM_MAG 2 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

(see Table 5 and Table 6)

Event Capture Overview

The ADIS16204 also provides a dual-channel, capture function.

Figure 24 provides an example of a captured waveform. A dedi-

cated set of programmable control registers govern the operation

of this function, controlling the data source: trigger settings

(level, direction and data source), memory depth, pretrigger

data length, and data storage. In systems that require specific

event monitoring, this feature simplifies system integration by

reducing the burden on the system’s processor. One convenient

feature is the fact that the trigger source does not have to be the

data that is captured.

5

10

15

20

0

–5

–15

–10

–20

0

100

200

300

400

500

600

700

800

900

1000

SAMPLE –

TRIGGER THRESHOLD: 7.4g

DATA SOURCE: Y-AXIS ACCELERATION

PRE-TRIGGER

DATA

LENGTH

Figure 24. Event Capture Example

Event Capture Configuration

The event capture buffers use the alarms as their trigger source.

Therefore, the first two configuration steps are the same. After

setting the trigger data source(s) and threshold(s), follow these

steps to complete the event capture setup:

1.

Program The Data Source To Capture.

This requires a single write cycle, to configure the upper byte of

the CAPT_CFG register. For example, use the following pseudo

code to set X acceleration and Y acceleration as the data sources

for Capture Buffer 2 and Capture Buffer 1 respectively:

•

Write 0x23 to Address 0x39 [CAPT_CFG].