How to Use ADXL345: 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
• Free-fall detection in safety systems

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 pin configuration:

The ADXL345 can be used in a variety of circuits and applications. Below are the steps and considerations for using the component effectively.

The ADXL345 can communicate with an Arduino UNO using the I2C protocol. Follow these steps to connect the device:

1. Wiring:

   • Connect the VDD pin of the ADXL345 to the 3.3V pin on the Arduino.
   • Connect the GND pin of the ADXL345 to the GND pin on the Arduino.
   • Connect the SDA pin of the ADXL345 to the A4 pin on the Arduino (I2C data line).
   • Connect the SCL pin of the ADXL345 to the A5 pin on the Arduino (I2C clock line).
   • If using the I2C alternate address, connect the SDO/ALT_ADDR pin to GND.

2. Install Required Libraries:

   • Install the Adafruit_ADXL345 library from the Arduino Library Manager.

3. Example Code: Below is an example 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 the range to ±16g
     accel.setRange(ADXL345_RANGE_16_G);
     Serial.println("Range set to ±16g");
   }
   
   void loop() {
     sensors_event_t event;
     accel.getEvent(&event);
   
     // Print acceleration data
     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); // Delay for readability
   }
   

• Power Supply: Ensure the ADXL345 is powered within its specified voltage range (2.0V to 3.6V). Exceeding this range may damage the device.
• Pull-Up Resistors: When using I2C, ensure pull-up resistors (typically 4.7kΩ) are connected to the SDA and SCL lines.
• Interrupt Pins: The INT1 and INT2 pins can be configured for specific events, such as free-fall detection or activity monitoring.

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 scanning for devices using an I2C scanner sketch.

1. Can the ADXL345 operate at 5V?

   • No, the ADXL345 operates at a maximum of 3.6V. Use a level shifter if interfacing with a 5V system.

2. How do I change the measurement range?

   • Use the setRange() function in the library to set the range to ±2g, ±4g, ±8g, or ±16g.

3. What is the default I2C address of the ADXL345?

   • The default I2C address is 0x53. It can be changed to 0x1D by connecting the SDO/ALT_ADDR pin to VDD.

By following this documentation, you can effectively integrate the ADXL345 into your projects for reliable motion sensing and acceleration measurements.