ADIS16IMU1SLASHPCBZ datasheet(28/38 Pages) AD

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ADIS16486

Data Sheet

Rev. 0 | Page 28 of 38

Table 145. GPIO_CTRL Bit Definitions1

Bits

Description (Default = 0x00X0)

[15:8]

Don’t care

General-Purpose Input and Output Line 4 (DIO4) data level

General-Purpose Input and Output Line 3 (DIO3) data level

General-Purpose Input and Output Line 2 (DIO2) data level

General-Purpose Input and Output Line 1 (DIO1) data level

DIO4 direction control (1 = output, 0 = input)

DIO3 direction control (1 = output, 0 = input)

DIO2 direction control (1 = output, 0 = input)

DIO1 direction control (1 = output, 0 = input)

GPIO_CTRL, Bits[7:4] reflect the logic levels on the DIOx pins and do not have

a default setting.

When the FNCTIO_CTRL register does not configure a DIOx pin,

the GPIO_CTRL register provides register controls for general-

purpose use of the pin. GPIO_CTRL, Bits[3:0] provide input and

output assignment controls for each line. When the DIOx pins

are inputs, monitor their level by reading GPIO_CTRL, Bits[7:4].

When the DIOx pins are used as outputs, set their level by writing

to GPIO_CTRL, Bits[7:4]. For example, use the following

sequence to set the DIO1 and DIO3 pins as high and low

output lines, respectively, and set the DIO2 and DIO4 pins as

input lines:

1. Select Page 3 (DIN = 0x8003).

2. Set GPIO_CTRL, Bits[7:0] = 0x15 (DIN = 0x8815, then

DIN = 0x8900).

Miscellaneous Configuration, CONFIG

The CONFIG register (see Table 146 and Table 147) provides

configuration options for the linear g compensation in the

gyroscopes (on and off), point of percussion alignment for the

accelerometers (on and off), and the RTC function.

Table 146. CONFIG Register Definition

Page ID

Addresses

Default

Access

Flash Backup

0x03

0x0A, 0x0B

0x00C0

R/W

Yes

Table 147. CONFIG Bit Definitions

Bits

Description (Default = 0x00C0)

[15:8]

Not used

Linear g compensation for gyroscopes (1 = enabled)

Point of percussion alignment (1 = enabled)

[5:2]

Not used

RTC, daylight savings time (1: enabled, 0: disabled)

RTC control (1: relative and elapsed timer mode,

0: calendar mode)

Point of Percussion

CONFIG, Bit 6 offers a point of percussion alignment function

that maps the accelerometer sensors to the corner of the package

identified in Figure 29. To activate this feature, select Page 3

(DIN = 0x8003) and set CONFIG, Bit 6 = 1 (DIN = 0x8A40,

DIN = 0x8B00).

PIN 1

PIN 23

POINT OF PERCUSSION

ALIGNMENT REFERENCE POINT.

SEE CONFIG, BIT 6.

Figure 29. Point of Percussion Reference Point

Linear Acceleration Effect on Gyroscope Bias

The ADIS16486 includes first-order compensation for the

linear g effect in the gyroscopes, which uses the following

model:

















































ZPC

YPC

XPC

The linear g correction factors, LGXY, apply correction for linear

acceleration in all three directions to the data path of each

gyroscope (ωXPC, ωYPC, and ωZPC) at the rate of the data samples

(2460 SPS when using the internal clock). CONFIG, Bit 7

provides an on and off control for this compensation. The

factory default value for this bit activates this compensation. To

turn the compensation off, select Page 3 (DIN = 0x8003) and

set CONFIG, Bit 7 = 0 (DIN = 0x8A40, then DIN = 0x8B00).

This command sequence also preserves the default setting for

the point of percussion alignment function (on).

Decimation Filter, DEC_RATE

The DEC_RATE register (see Table 148 and Table 149) provides

user control for the final filter stage (see Figure 24), which

averages and decimates the accelerometer and gyroscope data,

while also extending the time that the delta angle and delta

velocity track between each update. The output sample rate is

equal to 2460/(DEC_RATE + 1). When using the external clock

option (FNCTIO_CTRL, Bits[7:4], see Figure 24), replace 2460 in

this relationship with the input clock frequency. For example,

select Page 3 (DIN = 0x8003), and set DEC_RATE = 0x18 (DIN

= 0x8C18, then DIN = 0x8D00) to reduce the output sample rate

to 98.4 SPS (2460 ÷ 25).

Table 148. DEC_RATE Register Definition

Page ID

Addresses

Default

Access

Flash Backup

0x03

0x0C, 0x0D

0x0000

R/W

Yes

Table 149. DEC_RATE Bit Definitions

Bits

Description (Default = 0x0000)

[15:11]

Don’t care

[10:0]

Decimation rate, binary format, maximum = 2047, see

Figure 24 for the impact on sample rate

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