How to Use ADXL375: Examples, Pinouts, and Specs

The ADXL375 is a low-power, 3-axis accelerometer with a digital output, designed for motion sensing applications. It features a wide measurement range of ±200 g, high resolution, and built-in digital filtering capabilities. This makes it ideal for applications requiring precise motion detection, such as industrial vibration monitoring, impact detection, and sports equipment analysis.

• Impact and shock detection
• Industrial equipment monitoring
• Sports and fitness devices
• Automotive crash testing
• Structural health monitoring

The ADXL375 is typically available in a 14-pin LGA package. Below is the pinout description:

1. Power Supply: Connect the VDD pin to a 2.0 V to 3.6 V power source and the GND pin to ground.
2. Communication Interface: Choose between SPI or I²C communication:
   • For SPI, connect the CS, SDO, SDA, and SCL pins to the corresponding SPI pins on your microcontroller.
   • For I²C, connect the SDA and SCL pins to the I²C bus, and use a pull-up resistor (typically 4.7 kΩ) on each line.
3. Configuration: Configure the ADXL375's registers to set the desired measurement range, bandwidth, and output data rate.
4. Data Reading: Continuously read acceleration data from the X, Y, and Z axes via the selected communication interface.

• Bypass Capacitor: Place a 0.1 µF ceramic capacitor close to the VDD pin to reduce noise.
• Mounting: Ensure the ADXL375 is securely mounted to minimize mechanical noise and improve measurement accuracy.
• Interrupts: Use the built-in interrupt pins for event detection, such as free-fall or impact events.

#include <Wire.h>

// ADXL375 I²C address (default: 0x53)
#define ADXL375_ADDRESS 0x53

// Register addresses
#define POWER_CTL 0x2D
#define DATA_FORMAT 0x31
#define DATAX0 0x32

void setup() {
  Wire.begin(); // Initialize I²C communication
  Serial.begin(9600); // Initialize serial communication for debugging

  // Initialize ADXL375
  Wire.beginTransmission(ADXL375_ADDRESS);
  Wire.write(POWER_CTL); // Select Power Control register
  Wire.write(0x08); // Set measurement mode
  Wire.endTransmission();

  Wire.beginTransmission(ADXL375_ADDRESS);
  Wire.write(DATA_FORMAT); // Select Data Format register
  Wire.write(0x0B); // Set full resolution and ±200 g range
  Wire.endTransmission();
}

void loop() {
  int16_t x, y, z;

  // Request data from ADXL375
  Wire.beginTransmission(ADXL375_ADDRESS);
  Wire.write(DATAX0); // Start reading from DATAX0 register
  Wire.endTransmission(false);
  Wire.requestFrom(ADXL375_ADDRESS, 6); // Read 6 bytes (X, Y, Z)

  if (Wire.available() == 6) {
    x = (Wire.read() | (Wire.read() << 8)); // Combine low and high bytes for X
    y = (Wire.read() | (Wire.read() << 8)); // Combine low and high bytes for Y
    z = (Wire.read() | (Wire.read() << 8)); // Combine low and high bytes for Z
  }

  // Print acceleration values
  Serial.print("X: "); Serial.print(x);
  Serial.print(" Y: "); Serial.print(y);
  Serial.print(" Z: "); Serial.println(z);

  delay(100); // Delay for readability
}

1. No Data Output:

   • Ensure the ADXL375 is powered correctly (check VDD and GND connections).
   • Verify that the communication interface (SPI/I²C) is configured properly.
   • Check the register configuration, especially the POWER_CTL register.

2. Incorrect Acceleration Values:

   • Confirm that the data format and measurement range are set correctly.
   • Ensure the device is mounted securely to avoid mechanical noise.

3. I²C Communication Failure:

   • Check the pull-up resistors on the SDA and SCL lines.
   • Verify the I²C address (default is 0x53, but it may change if the ALT pin is used).

• Use an oscilloscope or logic analyzer to monitor the communication lines.
• Refer to the ADXL375 datasheet for detailed register descriptions and configuration options.
• Test the accelerometer with a simple script to verify basic functionality before integrating it into a larger project.

Q: Can the ADXL375 detect free-fall events?
A: Yes, the ADXL375 has built-in free-fall detection, which can be configured using its interrupt registers.

Q: What is the maximum sampling rate of the ADXL375?
A: The ADXL375 supports a maximum output data rate of 3200 Hz, but the bandwidth is limited to 1600 Hz.

Q: Can I use the ADXL375 with a 5V microcontroller?
A: Yes, but you will need a level shifter to interface the 3.3V logic of the ADXL375 with the 5V logic of the microcontroller.