7Semi BMA400 3-Axis Digital Accelerometer Breakout Board STEMMA QT / Qwiic
7Semi BMA400 3-Axis Digital Accelerometer Breakout (STEMMA QT / Qwiic) Technical Information
Overview
The 7Semi BMA400 Breakout is a 3-axis ultra-low power digital accelerometer module based on the Bosch BMA400 MEMS sensor.
Measures acceleration in X, Y, Z axes
Provides digital output (I2C/SPI)
Designed for low-power motion sensing applications
Optimized for wearables, IoT, and battery-powered systems
Working Principle
Uses MEMS capacitive sensing:
Acceleration displacement of microstructure
Change in capacitance electrical signal
Internal system:
Signal conditioning
ADC conversion
Digital processing
Outputs calirement Characteristics
Axes: 3-axis (X, Y, Z)
Measurement Range:
2g / 4g / 8g / 16g
Resolution:
12-bit digital output
Sensitivity:
Up to ~0.001g resolution
Output Data Rate:
12.5 Hz to 800 Hz
Electrical Characteristics
Operating Voltage (sensor): 1.72V 3.6V
Breakout Support: 3.3V / 5V compatible
Power Consumption
Active mode: < 14.5 A
Sleep mode: ~0.8 A
Extremely low power ideal for long battery life devices
Communication Interface
I2C (default)
SPI (optional)
Alternate:
0x15
Breakout Board Features
STEMMA QT / Qwiic connector (JST-SH 4-pin)
2.54mm header pins (breadboard compatible)
Plug-and-play I2C connectivity
Cable-based quick connection support
Interrupt & Smart Features
Two configurable interrupt pins
Built-in Detection Functions:
Step counting
Activity recognition
Tap / double-tap detection
Orientation / tilt detection
Motion / wake-up detection
Reduces MCU processing load (on-chip intelligence)
Internal Architecture
MEMS accelerometer sensor
ADC (12-bit)
Digital signal processor
Motion recognition engine
Interrupt controller
Functional Behavior
Continuously measures acceleration
Can operate h-performance mode
Generates interrupts on:
Motion events
Orientation change
Performance Characteristics
Ultra-low noise measurement
High stability and repeatability
Optimized for low-frequency motion detection
Suitable for always-on sensing
Key Technical Features
3-axis digital acceleration sensing
Ultra-low power consumption
12-bit resolution
Multiple selectable ranges
Built-in motion intelligence
I2C & SPI support
STEMMA QT / Qwiic compatibility
Breadboard-friendly design
Advantages
Very low power (best in class for accelerometers)
Integrated step counting & activity detection
Easy wiring via Qwiic/STEMMA
Flexible configuration
High accuracy for motion sensing
roscope (only acceleration)
Limited resolution compared to 16-bit IMUs Not ideal for high-speed vibration analysis Requires configuration for advanced features
Applications
Wearable devices (fitness trackers)
Step counters / activity monitors
IoT motion detection systems
Smart home automation
Tilt/orientation sensing
Low-power embedded systems
Technical Summary
The BMA400 breakout is an ultra-low power 3-axis accelerometer module that:
Provides accurate motion sensing with minimal power usage
Includes built-in motion intelligence (step, tap, orientation)
Supports easy integration via Qwiic/STEMMA and I2C
It is best suited for:
Battery-powered projects
Wearables and always-on sensing sy