ADIS16220

Rev. 0 | Page 13 of 20

Table 20. ALM_MAG1 and ALM_MAG2 Bit Descriptions

Bit

Description (Default = 0x0000)

[15:0]

Data bits for AIN1, AIN2 signal threshold setting;

twos complement, 305.18 μV/LSB.

Range = +8191 LSBs/−8192 LSBs.

Table 21. ALM_MAGS Bit Descriptions

Bit

Description (Default = 0x0000)

[15:12]

Reserved.

[11:0]

Data bits for temperature or supply threshold setting.

Binary format matches CAPT_TEMP or CAPT_SUPPLY

format, depending on the ALM_CTRL[4] setting.

Each ALM_MAGx register has a corresponding error flag in the

DIAG_STAT register for software monitoring of alarm

conditions. Note that the system alarm in the ALM_MAGS

register (see Table 21) has an error flag in DIAG_STAT[11] but

cannot trigger a data capture.

Table 22. Example Event Mode Configuration Sequence

DIN

Description

0xA00C,

0xA102

Set acceleration trigger point at >+10 g and <−10 g by

setting ALM_MAGA = 0x020C.

0xA809

Set the system alarm as a greater-than-temperature

configuration and enable both acceleration and system

alarms by setting ALM_CTRL[7:0] = 0x09.

0xB61F

Keep DIO1 as a busy indicator and set DIO2 as a positive

alarm indicator by setting DIO_CTRL[7:0] = 0x1F.

0x9C5A

Set capture into event mode, enable automatic capture

store to flash, enable power-down between captures,

and set pre-event capture length to 128 samples by

setting CAPT_CTRL[7:0] = 0x5A.

0xBF08

Start the event capture mode by setting GLOB_CMD[11] = 1

Power-Down Control

CAPT_CTRL[1] provides an option to automatically power

down the device after a capture event to reduce power consump-

tion. Wake the device from power-down by lowering CS. The

timer in automatic mode can wake the device up as well. Allow

for a 2 ms wake-up time after lowering CS to wake the device

up. Communication with the device while in sleep mode wakes

up the device. The device remains awake until after the next

capture or until the device is manually put back to sleep. When

data is extracted after a capture, the user can command the

device to go back to sleep by setting GLOB_CMD[1] = 1 (DIN

= 0xBE02). When waking multiple devices, CS must occur at

different times to avoid conflicts on the DOUT line.

Automatic Flash Back-Up Control

CAPT_CTRL[6] provides an option for automatically storing

capture buffer data to a mirror location in the nonvolatile flash

memory at the end of a capture. When an alarm condition has

been met, the device also performs a system backup, which

stores the registers and capture buffers in flash memory. Set

GLOB_CMD[13] = 1 (DIN = 0xBF40) to recover these settings

from the flash memory.

Use the following equations to estimate capture times:

)

flash

with

(

2

1024

184

,

97

1

516

.

0

)

flash

no

(

2

1024

184

,

97

1

014

.

0

_

_

CNT

AVG

C

CNT

AVG

C

T

T

















See Table 24 for the AVG_CNT setting.

GLOBAL COMMANDS

The GLOB_CMD register provides an array of single-write

commands for convenience. Setting the assigned bit in Table 23

to 1 activates each function. When the function completes, the

bit restores itself to 0. For example, clear the capture buffers using

a single DIN write sequence, DIN = 0xBF01. All of the commands

in the GLOB_CMD register require the power supply to be

within normal limits for the execution times listed in Table 23.

The execution times reflect the factory default configuration

where applicable and describe the time required to return to

normal operation.

Table 23. GLOB_CMD Bit Descriptions

Bit

Description

Execution Time1

[15:14]

Reserved

N/A

[13]

Restore capture data and settings

from flash memory

0.88 ms (no capture)

6.91 ms (with capture)

[12]

Copy capture data and settings to

flash memory

350 ms (no capture)

502 (with capture)

[11]

Capture mode start/stop

N/A

[10]

Set CAPT_PNTR = 0x0000

0.037 ms

[9]

Reserved

N/A

[8]

Clear capture buffers

0.84 ms

[7]

Software reset

22.7 ms

[6]

Reserved

N/A

[5]

Flash test, compare sum of flash

memory with the sum of SRAM

10.5 ms

[4]

Clear DIAG_STAT register

0.035 ms

[3]

Factory setting restore

335 ms

[2]

Self-test

12 ms

[1]

Power-down, requires toggling CS

low to wake up

N/A

[0]

Autonull

678 ms

the device returning to normal operation.

FILTERING

The ADIS16220 provides an averaging/decimation filter for

lower bandwidth applications that may value finer frequency

resolution using the 1024-sample capture buffer.

MEMS

SENSOR

AVERAGING

FILTER

N

+

TO

CAPTURE

MEMORY

AND

OUTPUT

REGISTERS

OFFSET

NULL

REGISTER

÷ N

POWER

SUPPLY

COMPEN-

SATION

ADC

Figure 15. Simplified Signal Processing Flowchart