Preliminary Technical Data

ADIS16220

Rev. PrE | Page 13 of 16

Table 21. GLOB_CMD Bit Descriptions

Bit

Description

Execution Time1

[15:14]

Not used

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]

Not used

N/A

[8]

Clear capture buffers

0.84 ms

[7]

Software reset

22.7 ms

[6]

Not used

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

ADC

Figure 15. Simplified Signal Processing Flowchart

AVG_CNT[3:0] controls the averaging/decimating filter

structure in binomial steps, starting with 1 and ending with

1024. For example, set AVG_CNT[7:0] = 0x08 (DIN = 0xB608)

to select 256 averages and a decimation rate of 1/256. Note that

Table 22. AVG_CNT Bit Descriptions

Bit

Description (Default = 0x0000)

[15:4]

Not used

[3:0]

Power-of-two setting for number of averages, binary

OFFSET ADJUSTMENT

The ACCL_NULL, AIN1_NULL and AIN2_NULL registers

provide a bias adjustment function. For example, setting

ACCL_NULL = 0x009C (DIN = 0x829C) increases the accelera-

tion bias by 156 LSB (3 g). Set GLOB_CMD[0] = 1 (DIN =

0x3E01) to execute the autonull function, which loads the

offset registers with a value derived from a 678 ms average of

the acceleration data.

Table 23. ACCL_NULL Bit Descriptions

Bit

Description (Default = 0x0000)

[15:0]

Data bits, twos complement, 19.073 mg/LSB

sensitivity. See Figure 15 for impact on output.

Range = +8191/−8192 LSBs

Table 24. AIN1_NULL, AIN2_NULL Bit Descriptions

Bit

Description (Default = 0x0000)

[15:0]

Data bits, twos complement, 305.18 μV/LSB

sensitivity. Signal path is similar to Figure 15.

Range = +8191/−8192 LSBs

INPUT/OUTPUT FUNCTIONS

DIO1 and DIO2 are configurable as I/O lines that serve mul-

tiple purposes. The following register priority governs their

operation: DIO_CTRL, then GPIO_CTRL. The DIO_CTRL

register has four application-specific configuration options for

each signal. The capture trigger input option works in conjunction

with the manual capture mode and provides a hardware option

for driving a data capture event. When enabled, this function

searches for a positive pulse and the capture starts on the falling

edge of this pulse. The busy indicator output is active during

capture events and can help prevent undesirable interruptions.

For example, set DIO_CTRL[5:0] = 101111 (DIN = 0xB62F) to

establish DIO2 as a capture trigger input and keep DIO1 as a

positive polarity, busy indicator output. Using the busy indicator

as an interrupt driver enables the master processor to gather

capture data as soon as it is available, without having to poll

inputs or estimate execution times. The alarm indicator output

is active when the trigger set by ALM_CTRL and ALM_MAGx

activates. When configured as general-purpose lines, the

GPIO_CTRL register configures DIO1 and DIO2. For example,

set GPIO_CTRL = 0x0103 (DIN = 0xB203, then 0xB301) to set

DIO1 and DIO2 as outputs, with DIO1 in a 1 state and DIO2 in

a 0 state.

Table 25. DIO_CTRL Bit Descriptions

Bit

Description (Default = 0x000F)

[15:6]

Not used

[5:4]

DIO2 function selection

00 = general-purpose I/O (use GPIO_CTRL)

01 = alarm indicator output (per ALM_CTRL)

10 = capture trigger inputs

11 = busy indicator output

[3:2]

DIO1 function selection

00 = general-purpose I/O (use GPIO_CTRL)

01 = alarm indicator output (per ALM_CTRL)

10 = capture trigger inputs

11 = busy indicator output

[1]

DIO2 line polarity, If [5:4] = 00, see GPIO_CTRL

1 = active high

0 = active low

[0]

DIO1 line polarity, If [3:2] = 00, see GPIO_CTRL

1 = active high

0 = active low