ADIS16400/ADIS16405
Rev. B | Page 16 of 20
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
comparison, dynamic rate-of-change comparison, and output
indicator configurations. The ALM_MAGx registers establish the
trigger threshold and polarity configurations.
Table 27 gives an example of how to configure a static alarm.
The ALM_SMPLx registers provide the number of samples to
use in the dynamic rate-of-change configuration. The period
equals the number in the ALM_SMPLx register multiplied by
the sample period time, which is established by the SMPL_PRD
register. See Table 28 for an example of how to configure the
sensor for this type of function.
Table 24. ALM_CTRL Bit Designations
Bits Settings Description Default = 0x0000
[15:12] Alarm 2 source selection
0000 Disable
0001 Power supply output
0010 X-axis gyroscope output
0011 Y-axis gyroscope output
0100 Z-axis gyroscope output
0101 X-axis accelerometer output
0110 Y-axis accelerometer output
0111 Z-axis accelerometer output
1000 X-axis magnetometer output
1001 Y-axis magnetometer output
1010 Z-axis magnetometer output
1011 Gyroscope temperature output
1100 Auxiliary ADC input
[11:8] Alarm 1 source selection (same as Alarm 2)
[7]
Rate-of-change (ROC) enable for Alarm 2
1 = rate of change, 0 = static level
[6]
Rate-of-change (ROC) enable for Alarm 1
1 = rate of change, 0 = static level
[5] Not used
[4]
Comparison data filter setting
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 = DIO2, 0 = DIO1
Table 25. ALM_MAG1, ALM_MAG2
Bits Description Default = 0x0000
[15]
Comparison polarity
1 = greater than, 0 = less than
[14] Not used
[13:0]
Data bits that match the format of the trigger
source selection
Table 26. ALM_SMPL1, ALM_SMPL2
Bits Description Default = 0x0000
[15:8] Not used
[7:0]
Data bits: number of samples
(both 0x00 and 0x01 = 1)
Table 27. Alarm Configuration Example 1
DIN Description
0xAF55,
0xAE17
ALM_CTRL = 0x5517.
Alarm 1 input = XACCL_OUT.
Alarm 2 input = XACCL_OUT.
Static level comparison, filtered data.
DIO2 output indicator, positive polarity.
0xA783,
0xA641
ALM_MAG1 = 0x8341.
Alarm 1 is true if XACCL_OUT > +0.5 g.
0xA93C,
0xA8BF
ALM_MAG2= 0x3CBF.
Alarm 2 is true if XACCL_OUT < −0.5 g.
Table 28. Alarm Configuration Example 2
DIN Description
0xAF76,
0xAE87
ALM_CTRL = 0x7687.
Alarm 1 input = ZACCL_OUT.
Alarm 2 input = YACCL_OUT.
Rate of change comparison, unfiltered data.
DIO2 output indicator, positive polarity.
0xB601 SMPL_PRD = 0x0001.
Sample rate = 819.2 SPS.
0xAB08 ALM_SMPL1 = 0x0008.
Alarm 1 rate of change period = 9.77 ms.
0xAC50 ALM_SMPL2= 0x0050.
Alarm 2 rate of change period = 97.7 ms.
0xA783,
0xA641
ALM_MAG1 = 0x8341.
Alarm 1 is true if XACCL_OUT > +0.5 g.
0xA93C,
0xA8BE
ALM_MAG2= 0x3CBE.
Alarm 2 is true if XACCL_OUT < −0.5 g.
