SmartElex BMA400 Triple Axis Accelerometer Breakout

Overview

The module is based on the BMA400 ultra-low-power 3-axis accelerometer IC, a high-precision MEMS motion sensor designed for low-power, always-on applications.

• Measures acceleration along:

  • X-axis

  • Y-axis

  • Z-axis

   

• Detects:

  • Motion

  • Tilt

  • Orientation

  • Vibration

   

It is optimized for ultra-low power consumption with high accuracy.

Working Principle

MEMS Capacitive Sensing

• Contains a microscopic suspended mass structure

• When acceleration occurs:

  • Mass shifts slightly

  • Changes capacitance between electrodes

   

citance variation electrical signal

Internal ADC converts signal into digital acceleration data

Output represents acceleration in g (gravity units).

Measurement Characteristics

Acceleration Range (Selectable)

• 2g

• 4g

• 8g

• 16g

Resolution

• Up to 12-bit / 16-bit equivalent resolution (mode dependent)

• High sensitivity for small motion detection

Output Data

• Digital acceleration values:

  • X, Y, Z axes

   

Electrical Characteristics

• Supply voltage: 1.71V to 3.6V

• Ultra-low power consumption:

  • ~0.8 A (low-power mode)

Ideal for battery-powered and always-on systems.

Communication Interface

• I2C interface

• SPI interface

Flexible and easy integration with microcontrollers.

Internal Features

Ultra-Low Power Design

• Designed for continuous operation with minimal energy use

Built-in Step Counter

• Detects steps using motion patterns

Activity / Inactivity Detection

• Detects:

  • Movement

  • No-motion conditions

Interrupt Engine

• Generates interrupts for:

  • Motion

  • Orientation

  • Tap events

FIFO Buffer

• Stores multiple samples

• Reduces proceuilt-in filters reduce noise

• Improves measurement stability

Operating Behavior

Static Measurement

• Measures gravity used for tilt detection

Dynamic Measurement

• Detects:

  • Motion

  • Vibration

  • Movement patterns

Always-On Monitoring

• Can run continuously with minimal power impact

Environmental Characteristics

• Operating temperature: 40C to +85C

• Stable across environmental conditions

Limitations

• Cannot measure:

  • Absolute position

• Accuracy affected by:

  • Mechanical vibrations

  • Noise

• Drift may occur in lion

  • VCC Power supply

  • GND Ground

  • SDA / MOSI Data

  • SCL / SCK Clock

  • CS Chip select (SPI)

  • INT Interrupt output

  Functional Role

  The module acts as a:

  • Motion sensor

  • Tilt/orientation detector

  • Activity monitoring device

  • Low-power inertial sensing component

  Summary

  The SmartElex BMA400 Accelerometer Breakout is a high-efficiency motion sensing module that:

  • Measures 3-axis acceleration (X, Y, Z)

  • Uses MEMS capacitive sensing technology

  • Offers ultra-low power consumption (~A level)

  • Includes step counting, interrupts, and filtering

  • Is optimized for always-on, battery-powered motion detection systems

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