Example Code for Arduino-Acquiring Motion Status and Heading Angle via I2C

Hardware Preparation

• DFR1222 FireBeetle 2 ESP32-C5 ×1
• SEN0695 Fermion: BMI323+BMM350 9 DOF IMU Sensor ×1

Software Preparation

• Download and install Arduino IDE: Download Arduino IDE

• Download and install the DFRobot_BMI323 library: Download the DFRobot_BMI323 library

• Download and install the DFRobot_BMM350 library: Download the DFRobot_BMM350 library

• Library Installation Guide: View Installation Guide

Wiring Diagram

Connect the 9-axis IMU sensor to the ESP32-C5 as shown in the diagram. Core pin connections:

• Sensor pin “3V3” → ESP32-C5 3.3V
• Sensor pin “GND” → ESP32-C5 GND
• Sensor pin “INT1” → ESP32-C5 GPIO27
• Sensor pin “INT2” → ESP32-C5 GPIO26
• Sensor I2C pin “SCL” → ESP32-C5 SCL (default GPIO10)
• Sensor I2C pin “SDA” → ESP32-C5 SDA (default GPIO9)
• I²C address pad configuration: Leave the I²C address pads of BMI323 and BMM350 open. In this state, the I²C address of BMI323 is 0x69, and the I²C address of BMM350 is 0x15 (factory default mode).

Sample Code

#include "DFRobot_BMI323.h"
#include "DFRobot_BMM350.h"

// I2C address definitions
#define BMI323_I2C_ADDR  0x69    
#define BMM350_I2C_ADDR  0x15    

// Interrupt pin definitions (modify according to actual wiring)
#define INT1_PIN         27       // BMI323 INT1 → GPIO27 (any motion)
#define INT2_PIN         26       // BMI323 INT2 → GPIO26 (no motion)

// Create sensor objects
DFRobot_BMI323 bmi323(&Wire, BMI323_I2C_ADDR);
DFRobot_BMM350_I2C bmm350(&Wire, BMM350_I2C_ADDR);

// Interrupt flags
volatile bool gAnyMotionFlag = false;
volatile bool gNoMotionFlag  = false;

// Motion state enumeration
enum MotionState {
  STATE_UNKNOWN,
  STATE_MOVING,
  STATE_STILL
};
MotionState currentState = STATE_UNKNOWN;

// Direction names array
const char* directionNames[] = {
  "North", "Northeast", "East", "Southeast",
  "South", "Southwest", "West", "Northwest"
};

// Interrupt service routines
void IRAM_ATTR interruptAnyMotion() {
  gAnyMotionFlag = true;
}

void IRAM_ATTR interruptNoMotion() {
  gNoMotionFlag = true;
}

/**
 * @brief Convert heading angle to direction name
 * @param heading Heading angle (0~360°)
 * @return Direction name string
 */
const char* getDirectionName(float heading) {
  int index = (int)((heading + 22.5f) / 45.0f) % 8;
  return directionNames[index];
}

void setup() {
  Serial.begin(115200);
  while (!Serial) delay(10);

  Serial.println("\n=== BMI323 Motion Detector + BMM350 Compass ===");

  // ---------- Initialize BMI323 ----------
  Serial.print("Initializing BMI323... ");
  while (!bmi323.begin()) {
    Serial.println("Failed, retry in 1s");
    delay(1000);
  }
  Serial.println("OK");

  // Configure accelerometer
  if (!bmi323.configAccel(bmi323.eAccelODR50Hz, bmi323.eAccelRange8G, bmi323.eAccelModeNormal)) {
    Serial.println("Error: BMI323 accelerometer config failed!");
    while (1) delay(1000);
  }

  // Configure any-motion detection (INT1)
  struct bmi3_any_motion_config anyMotionCfg;
  anyMotionCfg.duration    = 9;    // 9 * 20ms = 180ms
  anyMotionCfg.slope_thres = 9;    // 9 * 1.953mg ≈ 17.6mg
  anyMotionCfg.acc_ref_up  = 1;    // Always update reference
  anyMotionCfg.hysteresis  = 5;    // 5 * 1.953mg ≈ 9.8mg
  anyMotionCfg.wait_time   = 4;    // 4 * 20ms = 80ms

  if (!bmi323.enableAnyMotionInt(anyMotionCfg, bmi323.eINT1, bmi323.eAxisXYZ)) {
    Serial.println("Error: Failed to enable any-motion interrupt!");
    while (1) delay(1000);
  }

  // Configure no-motion detection (INT2)
  struct bmi3_no_motion_config noMotionCfg;
  noMotionCfg.duration    = 9;    // 9 * 20ms = 180ms
  noMotionCfg.slope_thres = 9;    // 9 * 1.953mg ≈ 17.6mg
  noMotionCfg.acc_ref_up  = 1;    // Always update reference
  noMotionCfg.hysteresis  = 5;    // 5 * 1.953mg ≈ 9.8mg
  noMotionCfg.wait_time   = 5;    // 5 * 20ms = 100ms

  if (!bmi323.enableNoMotionInt(noMotionCfg, bmi323.eINT2, bmi323.eAxisXYZ)) {
    Serial.println("Error: Failed to enable no-motion interrupt!");
    while (1) delay(1000);
  }

  // Configure ESP32 external interrupts
  attachInterrupt(digitalPinToInterrupt(INT1_PIN), interruptAnyMotion, RISING);
  attachInterrupt(digitalPinToInterrupt(INT2_PIN), interruptNoMotion, RISING);

  // ---------- Initialize BMM350 ----------
  Serial.print("Initializing BMM350... ");
  while (bmm350.begin()) {   // begin() returns 0 on success, non-zero on failure
    Serial.println("Failed, retry in 1s");
    delay(1000);
  }
  Serial.println("OK");

  // Set operation mode to normal mode
  bmm350.setOperationMode(eBmm350NormalMode);

  // Set preset mode to high accuracy, data rate 25Hz
  bmm350.setPresetMode(BMM350_PRESETMODE_HIGHACCURACY, BMM350_DATA_RATE_25HZ);

  // Enable X, Y, Z axis measurements
  bmm350.setMeasurementXYZ();

  Serial.println("Setup complete! Monitoring motion and compass.\n");
}

void loop() {
  static unsigned long lastPrint = 0;
  unsigned long now = millis();

  // Handle motion interrupts
  if (gAnyMotionFlag) {
    gAnyMotionFlag = false;
    uint16_t status = bmi323.getIntStatus();
    if (status & BMI3_INT_STATUS_ANY_MOTION) {
      if (currentState != STATE_MOVING) {
        currentState = STATE_MOVING;
        float heading = bmm350.getCompassDegree();
        const char* dirName = getDirectionName(heading);
        Serial.print("[");
        Serial.print(now);
        Serial.print("] State: MOVING | Direction: ");
        Serial.print(dirName);
        Serial.print(" (");
        Serial.print(heading, 1);
        Serial.println("°)");
      }
    }
  }

  if (gNoMotionFlag) {
    gNoMotionFlag = false;
    uint16_t status = bmi323.getIntStatus();
    if (status & BMI3_INT_STATUS_NO_MOTION) {
      if (currentState != STATE_STILL) {
        currentState = STATE_STILL;
        float heading = bmm350.getCompassDegree();
        const char* dirName = getDirectionName(heading);
        Serial.print("[");
        Serial.print(now);
        Serial.print("] State: STILL | Direction: ");
        Serial.print(dirName);
        Serial.print(" (");
        Serial.print(heading, 1);
        Serial.println("°)");
      }
    }
  }

  // Output current state and direction every second
  if (now - lastPrint >= 1000) {
    lastPrint = now;
    float heading = bmm350.getCompassDegree();
    const char* dirName = getDirectionName(heading);
    const char* stateStr = (currentState == STATE_MOVING) ? "MOVING" : 
                           (currentState == STATE_STILL) ? "STILL" : "UNKNOWN";
    Serial.print("[");
    Serial.print(now);
    Serial.print("] State: ");
    Serial.print(stateStr);
    Serial.print(" | Direction: ");
    Serial.print(dirName);
    Serial.print(" (");
    Serial.print(heading, 1);
    Serial.println("°)");
  }

  delay(10);
}

Result