ADIS16201SLASHPCB datasheet(21/32 Pages) AD

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Data Sheet

ADIS16201

Rev. C | Page 21 of 32

YINCL_SCALE Register Definition

Address

Scale1

Default

Format

Access

0x1F, 0x1E

0.0488%

0x0800

Binary

R/W

Scale is the weight of each LSB.

The YINCL_SCALE register is the user-controlled register for

calibrating system-level inclination sensitivity errors. For the

Y-axis inclination, it represents the A variable in the calibration

equation. The calibration range is from 0 to 2, or 0 to 4095 codes,

assuming nominal sensor sensitivity. The contents of this register

are nonvolatile.

Table 18. YINCL_SCALE Bit Designations

Bit

Description

15:12

Not used

11:0

Data bits

ALARMS

The ADIS16201 contains two independent alarm functions that are

referred to as Alarm 1 and Alarm 2. The Alarm 1 function is

managed by the ALM_MAG1 and ALM_SMPL1 control registers.

The Alarm 2 function is managed by the ALM_MAG2 and

ALM_SMPL2 control registers. Both the Alarm 1 and Alarm 2

functions share the ALM_CTRL register. For simplicity, the

following text references the Alarm 1 functionality only.

The 16-bit ALM_CTRL register serves three distinct roles in

controlling the Alarm 1 function. First, it is used to enable the

overall Alarm 1 function and select the output data variable that

is to be monitored for the alarm condition. Second, it is used to

select whether the Alarm 1 function is based upon a predefined

threshold (THR) level or a predefined rate-of-change (ROC)

slope. Third, the ALM_CTRL register can be used in setting up

one of the two general-purpose input/output lines (GPIOs) to

serve as a hardware output that indicates when an alarm

condition has occurred. Enabling the I/O alarm function,

setting its polarity, and controlling its operation are

accomplished using this register.

Note that when enabled, the hardware output indicator serves

both the Alarm 1 and Alarm 2 functions and cannot be used to

differentiate between one alarm condition and the other. It is

simply used to indicate that an alarm is active and that the user

should poll the device via the SPI to determine the source of the

alarm condition (see the STATUS Register Definition section).

Because the ALM_CTRL, MSC_CTRL, and GPIO_CTRL

control registers can influence the same GPIO pins, a priority

level has been established to avoid conflicting assignments of

the two GPIO pins. This priority level is defined as

MSC_CTRL, which has precedence over ALM_CTRL, which

has precedence over GPIO_CTRL.

The ALM_MAG1 control register used in controlling the

Alarm 1 function has two roles. The first role is to store the

value with which the output data variable is compared to

discern if an alarm condition exists or not. The second role is to

identify whether the alarm should be active for excursions

above or below the alarm limit. If 1 is written to the GT1 bit of

the ALM_MAG1 control register, the alarm is active for

excursions extending above a given limit. If 0 is written to the

GT1 bit, the alarm is active for excursions dropping below the

given limit. The comparison value contained within the

ALM_MAG1 control register is located within the lower 14 bits.

The format utilized for this 14-bit value should match that of

the output data register that is being monitored for the alarm

condition. For instance, if the YINCL_OUT output data register

is being monitored by Alarm 1, then the 14-bit value within the

ALM_MAG1 control register takes on a twos complement

format with each LSB equating to nominal 0.1° (assumes unity

scale and zero offset factors). The ALM_MAG value is

compared against the instantaneous value of the parameter

being monitored.

Use caution when monitoring the temperature output register

for the alarm conditions. Here, the negative temperature scale

factor results in the greater than and less than selections

requiring reverse logic.

When the THR function is enabled, the output data variable is

compared against the ALM_MAG1 level. When the ROC

function is enabled, the comparison of the output data variable

is against the ALM_MAG1 level averaged over the number of

samples, as identified in the ALM_SMPL1 control register. This

acts to create a comparison of (Δ units/Δ time) or the derivative

of the output data variable against a predefined slope.

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