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
🔄 Signal Conversion
Capacitance 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 µA (low-power mode)
Higher in performance modes
👉 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 processor load
✔ Digital Filtering
Built-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: −40°C to +85°C
Stable across environmental conditions
⚠️ Limitations
Cannot measure:
Absolute position
Accuracy affected by:
Mechanical vibrations
Noise
Drift may occur in long-term motion integration
🔌 Typical Pin Configuration
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
Provides digital output via I²C/SPI
Offers ultra-low power consumption (~µA level)
Includes step counting, interrupts, and filtering
Is optimized for always-on, battery-powered motion detection systems
