Data Sheet ADIS16375
Rev. E | Page 23 of 28
ALARMS
The alarm function provides independent alarms for each
inertial sensor. Table 79 contains a list of registers that provide
configuration and control inputs for the alarm function.
Table 79. Registers for Alarm Configuration
Register Page Address Description
ALM_CONFIG1 3 0x20 Alarm configuration
ALM_CONFIG2 3 0x22 Alarm configuration
XG_ALM_MAG 3 0x40 X-axis gyroscope trigger
YG_ALM_MAG 3 0x42 Y-axis gyroscope trigger
ZG_ALM_MAG 3 0x44 Z-axis gyroscope trigger
XA_ALM_MAG 3 0x46 X-axis accelerometer trigger
YA_ALM_MAG 3 0x48 Y-axis accelerometer trigger
ZA_ALM_MAG 3 0x4A Z-axis accelerometer trigger
Static Alarm Use
The static alarm setting compares each sensor’s output with the
trigger settings in the xG_ALM_MAG and xA_ALM_MAG
registers (see Table 80, Table 81, Table 82, Table 83, Table 84,
and Table 85) of that sensor. The polarity controls for each alarm
are in the ALM_CONFIG_x registers (see Table 86 and Table 87).
The polarity establishes whether greater than or less than
produces an alarm condition. The comparison between the
xG_ALM_MAG (or xA_ALM_MAG) value and the output data
only applies to the upper word or 16 bits of the output data.
Table 80. XG_ALM_MAG (Page 3, Base Address = 0x40)
Bits Description (Default = 0x0000)
[15:0]
X-axis gyroscope alarm threshold settings; matches
format of the X_GYRO_OUT register in Table 11
Table 81. YG_ALM_MAG (Page 3, Base Address = 0x42)
Bits Description (Default = 0x0000)
[15:0]
Y-axis gyroscope alarm threshold settings; matches
format of the Y_GYRO_OUT register in Table 12
Table 82. ZG_ALM_MAG (Page 3, Base Address = 0x44)
Bits Description (Default = 0x0000)
[15:0]
Z-axis gyroscope alarm threshold settings; matches
format of the Z_GYRO_OUT register in Table 13
Table 83. XA_ALM_MAG (Page 3, Base Address = 0x46)
Bits Description (Default = 0x0000)
[15:0]
X-axis accelerometer alarm threshold settings; uses
the same format as X_ACCL_OUT, see Table 18
Table 84. YA_ALM_MAG (Page 3, Base Address = 0x48)
Bits Description (Default = 0x0000)
[15:0]
Y-axis accelerometer alarm threshold settings; uses
the same format as Y_ACCL_OUT, see Table 19
Table 85. ZA_ALM_MAG (Page 3, Base Address = 0x4A)
Bits Description (Default = 0x0000)
[15:0]
Z-axis accelerometer alarm threshold settings; uses
the same format as Z_ACCL_OUT, see Table 20
Dynamic Alarm Use
The dynamic alarm setting provides the option of comparing the
change in each sensor’s output over a period of 48.7 ms, with that
sensor’s xx_ALM_MAG register.
Alarm Reporting
Monitor each sensor’s alarm by reading the ALM_STS register
(see Tabl e 43), located in Page 0. The FNCIO_CTRL register
(see Tabl e 93) provides a control for establishing any of the
DIOx lines as an alarm indicator output signal.
Table 86. ALM_CONFIG_1 (Page 3, Base Address = 0x20)
Bits Description (Default = 0x0000)
[15] X-axis accelerometer alarm (1 = enabled)
[14] Not used
[13] X-axis accelerometer alarm polarity (1 = greater than)
[12] X-axis accelerometer dynamic enable (1 = enabled)
[11] Z-axis gyroscope alarm (1 = enabled)
[10] Not used
[9] Z-axis gyroscope alarm polarity (1 = greater than)
[8] Z-axis gyroscope dynamic enable (1 = enabled)
[7] Y-axis gyroscope alarm (1 = enabled)
[6] Not used
[5] Y-axis gyroscope alarm polarity (1 = greater than)
[4] Y-axis gyroscope dynamic enable (1 = enabled)
[3] X-axis gyroscope alarm (1 = enabled)
[2] Not used
[1] X-axis gyroscope alarm polarity (1 = greater than)
[0] X-axis gyroscope dynamic enable (1 = enabled)
Table 87. ALM_CONFIG_2 (Page 3, Base Address = 0x22)
Bits Description (Default = 0x0000)
[15:8] Not used
[7] Z-axis accelerometer alarm (1 = enabled)
[6] Not used
[5] Z-axis accelerometer alarm polarity (1 = greater than)
[4] Z-axis accelerometer dynamic enable (1 = enabled)
[3] Y-axis accelerometer alarm (1 = enabled)
[2] Not used
[1] Y-axis accelerometer alarm polarity (1 = greater than)
[0] Y-axis accelerometer dynamic enable (1 = enabled)
Alarm Example
Table 88 offers an alarm configuration example, which sets the X-axis
gyroscope alarm to trip when X_GYRO_OUT > 131.1°/sec (0x2710).
Table 88. Alarm Configuration Example 1
DIN Description
0xC010 Set XA_ALM_MAG[7:0] = 0x10
0xC127 Set XA_ALM_MAG[15:8] = 0x27
0xA006 Set ALM_CONFIG_1[7:0] = 0x06
0xA100 Set ALM_CONFIG_1[15:8] = 0x00