How to Use ADXL345 Accelerometer: Examples, Pinouts, and Specs

The ADXL345 is a small, thin, low-power, 3-axis accelerometer capable of high-resolution (13-bit) measurements at up to ±16g. It is designed for applications requiring precise motion sensing, tilt detection, and gesture recognition. The device supports both I2C and SPI communication protocols, making it versatile and easy to integrate into a wide range of projects.

• Motion sensing in mobile devices
• Tilt detection in gaming controllers
• Gesture recognition in wearable devices
• Vibration monitoring in industrial equipment
• Step counting and activity tracking in fitness devices

The ADXL345 offers a robust set of features and specifications that make it suitable for various applications. Below are the key technical details:

The ADXL345 is typically available in a 14-pin LGA package. Below is the pinout description:

The ADXL345 can be used in a variety of circuits and applications. Below are the steps to integrate and use the component effectively:

1. Wiring: Connect the ADXL345 to the Arduino UNO as follows:

   • VDD to 3.3V on the Arduino
   • GND to GND on the Arduino
   • SCL to A5 (I2C Clock)
   • SDA to A4 (I2C Data)
   • Leave CS unconnected or pull it high for I2C mode.

2. Install Required Libraries: Use the Adafruit_ADXL345 library for easy integration. Install it via the Arduino Library Manager.

3. Example Code: Below is a sample Arduino sketch to read acceleration data from the ADXL345:

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_ADXL345_U.h>

// Create an ADXL345 object
Adafruit_ADXL345_Unified accel = Adafruit_ADXL345_Unified(12345);

void setup() {
  Serial.begin(9600);
  // Initialize the ADXL345
  if (!accel.begin()) {
    Serial.println("Failed to find ADXL345 chip");
    while (1); // Halt if the sensor is not detected
  }
  Serial.println("ADXL345 initialized successfully!");
  
  // Set range to ±16g for maximum sensitivity
  accel.setRange(ADXL345_RANGE_16_G);
}

void loop() {
  sensors_event_t event;
  accel.getEvent(&event); // Get acceleration data
  
  // Print acceleration values for X, Y, and Z axes
  Serial.print("X: "); Serial.print(event.acceleration.x); Serial.print(" m/s^2 ");
  Serial.print("Y: "); Serial.print(event.acceleration.y); Serial.print(" m/s^2 ");
  Serial.print("Z: "); Serial.print(event.acceleration.z); Serial.println(" m/s^2");
  
  delay(500); // Wait for 500ms before the next reading
}

• Power Supply: Ensure the ADXL345 is powered with a voltage between 2.0V and 3.6V. Using 5V directly may damage the device.
• Pull-Up Resistors: For I2C communication, ensure pull-up resistors (typically 4.7kΩ) are connected to the SDA and SCL lines.
• Range Configuration: Set the measurement range (±2g, ±4g, ±8g, or ±16g) based on your application requirements for optimal sensitivity and resolution.

1. No Data Output

   • Cause: Incorrect wiring or communication protocol mismatch.
   • Solution: Double-check the connections and ensure the correct protocol (I2C or SPI) is selected.

2. Inconsistent Readings

   • Cause: Noise or improper grounding.
   • Solution: Use decoupling capacitors near the power pins and ensure a solid ground connection.

3. Device Not Detected

   • Cause: Incorrect I2C address or faulty sensor.
   • Solution: Verify the I2C address (default is 0x53) and try replacing the sensor.

Q: Can the ADXL345 operate at 5V?
A: No, the ADXL345 operates at a maximum of 3.6V. Use a voltage regulator or level shifter if interfacing with a 5V system.

Q: How do I switch between I2C and SPI modes?
A: The communication mode is determined by the CS pin. Pull CS high for I2C mode or low for SPI mode.

Q: What is the maximum sampling rate of the ADXL345?
A: The ADXL345 supports a maximum data output rate of 3200 Hz.

By following this documentation, you can effectively integrate and use the ADXL345 accelerometer in your projects.