ADIS16265 Просмотр технического описания (PDF) - Analog Devices

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ADIS16265

Programmable Digital Gyroscope Sensor

Analog Devices 

Data Sheet

THEORY OF OPERATION

The ADIS16260 and ADIS16265 integrate a MEMS gyroscope

with data sampling, signal processing, and calibration functions,

along with a simple user interface. This sensing system collects

data autonomously and makes it available to any processor system

that supports a 4-wire serial peripheral interface (SPI).

SENSING ELEMENT

The sensing element operates on the principle of a resonator

gyro. Two polysilicon sensing structures each contain a dither

frame that is electrostatically driven to resonance, producing

the necessary velocity element to produce a Coriolis force

during angular rate. At two of the outer extremes of each frame,

orthogonal to the dither motion, movable fingers are placed

between fixed pickoff fingers to form a capacitive pickoff

structure that senses Coriolis motion. The resulting signal is fed

into a series of gain and demodulation stages that produce the

electrical rate signal output. The differential structure minimizes

the response to linear acceleration (gravity, vibration, and so

on) and to EMI.

DATA SAMPLING AND PROCESSING

The ADIS16260 and ADIS16265 run autonomously, based on

the configuration in the user control registers. The analog

gyroscope signal feeds into an analog-to-digital converter

(ADC) stage, which passes digitized data into the controller for

data processing and register loading. Data processing in the

embedded controller includes correction formulas, filtering,

and checking for preset alarm conditions. The correction formulas

are unique for each individual ADIS16260/ADIS16265 and come

from the factory characterization of each device over a

temperature range of −40°C to +85°C.

MEMS

SENSOR

OUTPUT

REGISTERS

TEMP

SENSOR

AIN

SIGNALS

ADC

CONTROLLER

CONTROL

REGISTERS

CLOCK

Figure 7. Simplified Sensor Signal Processing Diagram

ADIS16260/ADIS16265

USER INTERFACE

SPI Interface

Data collection and configuration commands both use the SPI,

which consists of four wires. The chip select (CS) signal activates

the SPI interface, and the serial clock (SCLK) signal synchronizes

the serial data lines. The serial input data clocks into DIN on

the SCLK rising edge, and the serial output data clocks out of

DOUT on the SCLK falling edge. Many digital processor plat-

forms support this interface with dedicated serial ports and

simple instruction sets.

User Registers

The user registers provide addressing for all input/output

operations on the SPI interface. Each 16-bit register has its

own unique bit assignment and has two 7-bit addresses: one

for its upper byte and one for its lower byte. Table 7 provides

a memory map of the user registers, along with the function of

each register.

The control registers use a dual memory structure. The SRAM

controls operation while the part is on and facilitates all user

configuration inputs. The flash memory provides nonvolatile

storage for control registers that have flash backup (see Table 7).

Storing configuration data in the flash memory requires a separate

command (GLOB_CMD[3] = 1, DIN = 0xBE08). When the

device powers on or resets, the flash memory contents are

loaded into the SRAM, and the device then starts producing

data according to the configuration in the control registers.

NONVOLATILE

FLASH MEMORY

(NO SPI ACCESS)

MANUAL

FLASH

BACKUP

STARTUP

OR RESET

VOLATILE

SRAM

SPI ACCESS

Figure 8. SRAM and Flash Memory Diagram

Rev. D | Page 9 of 20

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