ADXL345 3-Axis Accelerometer Sensor
Overview
The Boardoza ADXL345 Breakout Board is a precision MEMS (Micro-Electro-Mechanical Systems) sensing module designed to measure static gravity and dynamic acceleration forces across three orthogonal axes (X, Y, Z). Built around the industry-standard Analog Devices ADXL345 chipset, this module delivers high-resolution (13-bit) digital output, making it capable of detecting inclination changes of less than 1.0°.
Engineered for versatility in embedded systems, the board features an integrated voltage regulator and logic level shifting, allowing for seamless interfacing with both 3.3V and 5V microcontrollers. Its ultra-low power consumption and advanced motion-detection features make it an ideal solution for mobile instrumentation, gaming peripherals, and industrial vibration monitoring systems.
Core Technical Specifications
The module is characterized by the following operational parameters:
Sensing Architecture: 3-Axis MEMS accelerometer with user-selectable full-scale measurement ranges of ±2g, ±4g, ±8g, and ±16g.
Resolution: Offers up to 13-bit resolution at ±16g (maintaining a 4 mg/LSB scale factor), enabling precise tilt calculations.
Operating Voltage: Supports a wide input range of 3.3V to 6V DC thanks to the onboard low-dropout (LDO) regulator, while the core sensor operates internally at low voltage.
Communication Interface: Flexible digital connectivity via SPI (3-wire or 4-wire) or I2C buses, selected via pin configuration.
Power Consumption: Extremely efficient operation, drawing as little as 40 µA in measurement mode and 0.1 µA in standby mode.
Data Rate: Configurable output data rates (ODR) ranging from 0.1 Hz to 3200 Hz, allowing optimization for low-power or high-frequency sampling.
Physical Dimensions: A compact 20 mm x 20 mm PCB footprint designed for space-constrained integration.
Key Engineering Features
Advanced Motion Detection Logic
Beyond raw acceleration data, the ADXL345 engine includes embedded logic for autonomous event detection:
Tap/Double Tap: Detects single or double impulses on any axis, useful for gesture control interfaces.
Activity/Inactivity: Monitors acceleration thresholds to determine if the device is in motion or stationary, enabling intelligent system sleep/wake cycles.
Free-Fall Detection: Identifies rapid 0g conditions indicating a drop event, commonly used in hard drive protection mechanisms.
Integrated FIFO Buffer
To reduce the processing load on the host microcontroller, the module features a 32-level First-In-First-Out (FIFO) memory buffer. This allows the sensor to store data samples locally, permitting the host processor to sleep until a burst of data is ready for retrieval, thereby significantly lowering overall system power consumption.
Flexible Interface Compatibility
The breakout design simplifies integration by exposing the necessary pins for both SPI and I2C protocols. It includes standard 0.1" pitch headers, making it compatible with breadboards and standard prototyping cables. The default I2C address is typically 0x53, but can be modified via the SDO/ALT ADDR pin.
Hardware Interface and Signal Mapping
The module provides a comprehensive 8-pin interface for power and data:
Power Terminals
VCC (or +5V): Main power input (3.3V - 6V). The onboard regulator steps this down for the sensor.
GND: Common system ground.
Digital Communication
SDA: Serial Data line for I2C (or SDI/SDIO for SPI). Bidirectional data transfer pin.
SCL: Serial Clock line. Provides the timing signal for I2C or SPI communication.
SDO: Serial Data Output (SPI MISO) or Alternate Address Select (I2C). Grounding or pulling this pin high changes the I2C address (0x53 vs 0x1D).
CS: Chip Select. Used to enable SPI mode (active low). For I2C operation, this is typically pulled high.
Interrupt Outputs
INT1 & INT2: Programmable interrupt pins. These can be mapped to trigger on specific events like data-ready, free-fall, or tap detection, alerting the host MCU immediately.
Applications
Mobile Devices: Screen orientation (portrait/landscape) detection and user interface gestures.
Industrial Monitoring: Vibration analysis for machinery health and predictive maintenance.
Robotics: Balance stability control and impact detection for autonomous platforms.
Medical Instrumentation: Activity monitoring in pedometers and wearable health trackers.
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