ADIS16228SLASHPCBZ datasheet(17/28 Pages) AD

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Data Sheet

ADIS16228

Rev. B | Page 17 of 28

SPECTRAL ALARMS

The alarm function offers six spectral bands for alarm detection.

Each spectral band has high and low frequency definitions,

along with two different trigger thresholds (Alarm 1 and Alarm 2)

for each accelerometer axis. Table 25 provides a summary of

each register used to configure the alarm function.

Table 25. Alarm Function Register Summary

Address

Description

ALM_F_LOW

0x20

Alarm frequency band, lower limit

ALM_F_HIGH

0x22

Alarm frequency band, upper limit

ALM_X_MAG1

0x24

X-Axis AlarmTrigger Level 1 (warning)

ALM_Y_MAG1

0x26

Y-Axis Alarm Trigger Level 1 (warning)

ALM_Z_MAG1

0x28

Z-Axis Alarm Trigger Level 1 (warning)

ALM_X_MAG2

0x2A

X-Axis Alarm Trigger Level 2 (fault)

ALM_Y_MAG2

0x2C

Y-Axis Alarm Trigger Level 2 (fault)

ALM_Z_MAG2

0x2E

Z-Axis Alarm Trigger Level 2 (fault)

ALM_PNTR

0x30

Alarm pointer

ALM_S_MAG

0x32

System alarm trigger level

ALM_CTRL

0x34

Alarm configuration

DIAG_STAT

0x3C

Alarm status

ALM_X_STAT

0x40

X-axis alarm status

ALM_Y_STAT

0x42

Y-axis alarm status

ALM_Z_STAT

0x44

Z-axis alarm status

ALM_X_PEAK

0x46

X-axis alarm peak

ALM_Y_PEAK

0x48

Y-axis alarm peak

ALM_Z_PEAK

0x4A

Z-axis alarm peak

ALM_X_FREQ

0x70

X-axis alarm frequency of peak alarm

ALM_Y_FREQ

0x72

Y-axis alarm frequency of peak alarm

ALM_Z_FREQ

0x74

Z-axis alarm frequency of peak alarm

The ALM_CTRL register (see Table 26) provides control bits

that enable the spectral alarms of each axis, configures the system

alarm, sets the record delay for the spectral alarms, and configures

the clearing function for the DIAG_STAT error flags (see Table 65).

Table 26. ALM_CTRL (Base Address = 0x34), Read/Write

Bits

Description (Default = 0x0080)

[15:12]

Not used.

[11:8]

Response delay; range = 0 to 15. Represents the number

of spectral records for each spectral alarm before a

spectral alarm flag is set high.

Latch DIAG_STAT error flags. Requires a clear status

command (GLOB_CMD[4]) to reset the flags to 0.

1 = enabled, 0 = disabled.

Enable DIO1 as an Alarm 1 output indicator and enable

DIO2 as an Alarm 2 output indicator. 1 = enabled.

System alarm comparison polarity.

1 = trigger when less than ALM_S_MAG[11:0].

0 = trigger when greater than ALM_S_MAG[11:0].

System alarm. 1 = temperature, 0 = power supply.

Alarm S enable (ALM_S_MAG). 1 = enabled, 0 = disabled.

Alarm Z enable (ALM_Z_MAG). 1 = enabled, 0 = disabled.

Alarm Y enable (ALM_Y_MAG). 1 = enabled, 0 = disabled.

Alarm X enable (ALM_X_MAG). 1 = enabled, 0 = disabled.

ALARM DEFINITION

The alarm function provides six programmable spectral bands,

as shown in Figure 19. Each spectral alarm band has lower and

upper frequency definitions for all of the sample rate options

(SRx). It also has two independent trigger level settings, which

are useful for systems that value warning and fault condition

indicators.

FREQUENCY

ALM_F_HIGH

ALM_F_LOW

ALM_x_MAG1

ALM_x_MAG2

Figure 19. Spectral Band Alarm Setting Example, ALM_PNTR = 0x03

Select the spectral band for configuration by writing its number

(1 to 6) to ALM_PNTR[2:0] (see Table 27). Then select the sample

rate option using ALM_PNTR[9:8]. This number represents a

binary number, which corresponds to the x in the SRx sample

rates option associated with REC_CTRL1[11:8] (see Table 9).

For example, set ALM_PNTR[7:0] = 0x05 (DIN = 0xB005) to

select Alarm Spectral Band 5, and set ALM_PNTR[15:8] = 0x02

(DIN = 0xB102) to select the SR2 sample rate option.

Table 27. ALM_PNTR (Base Address = 0x30), Read/Write

Bits

Description (Default = 0x0000)

[15:10]

Not used

[9:8]

Sample rate option; range = 0 to 3 for SR0 to SR3

[7:3]

Not used

[2:0]

Spectral band number; range = 1 to 6

Alarm Band Frequency Definitions

After the spectral band and sample rate settings are set, program

the lower and upper frequency boundaries by writing their bin

numbers to the ALM_F_LOW register (see Table 28) and

ALM_F_HIGH register (see Table 29). Use the bin width

definitions listed in Table 12 to convert a frequency into a bin

number for this definition. Calculate the bin number by dividing

the frequency by the bin width that is associated with the sample

rate setting. For example, if the sample rate is 5120 Hz and the

lower band frequency is 400 Hz, divide that number by the bin

width of 10 Hz to arrive at the 40th bin as the lower band setting.

Then set ALM_F_LOW[7:0] = 0x28 (DIN = 0xA028) to establish

400 Hz as the lower frequency for the 5120 SPS sample rate setting.

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