Example Code for Arduino-Reading Accumulated Step Count via I2C

Hardware Preparation

• DFR1222 FireBeetle 2 ESP32-C5 ×1
• SEN0693 Fermion: BMI323 6 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

• Library Installation Guide: View Installation Guide

Wiring Diagram

Connect the 6 DOF IMU sensor to the ESP32-C5 as shown in the diagram. The main connections are:

• Sensor pin “3V3” → ESP32-C5 3.3V
• Sensor pin “GND” → ESP32-C5 GND
• Sensor pin “INT1” → ESP32-C5 GPIO27
• Sensor I2C pin “SCL” → ESP32-C5 SCL (default GPIO10)
• Sensor I2C pin “SDA” → ESP32-C5 SDA (default GPIO9)
• I2C address pad configuration: Leave the pad open, the I2C address will be 0x69 (factory default mode)

Sample Code

#include "DFRobot_BMI323.h"

#define BMI323_I2C_ADDR 0x69  

DFRobot_BMI323 bmi323(&Wire, BMI323_I2C_ADDR);
volatile bool gStepReady = false;

// ESP32 interrupt function must be placed in IRAM
void IRAM_ATTR interrupt() {
  gStepReady = true;
}

void setup() {
  Serial.begin(115200);
  while (!Serial) {
  delay(10);   // Wait for serial initialization
}

  Serial.println("BMI323 Step Counter Demo");
  Serial.println("========================");

  // Initialize BMI323, retry on failure
  while (!bmi323.begin()) {
    Serial.println("I2C init failed, retry in 1s");
    delay(1000);
  }

  // Configure accelerometer: 50Hz sampling rate, ±8g range, normal mode
  bmi323.configAccel(bmi323.eAccelODR50Hz, bmi323.eAccelRange8G, bmi323.eAccelModeNormal);

  // Enable step counter interrupt on INT1 pin
  if (!bmi323.enableStepCounterInt(bmi323.eINT1)) {
    Serial.println("Enable step counter interrupt failed!");
    while (1) delay(1000);
  }

  // Connect BMI323 INT1 to ESP32 GPIO 27 (can be modified as needed)
  attachInterrupt(digitalPinToInterrupt(27), interrupt, RISING);

/* Correspondence table of AVR series Arduino interrupt pins and terminal numbers
 * ---------------------------------------------------------------------------------------
 * |                                        | Digital Pin | 2  | 3  |                   |
 * |    Uno, Nano, Mini, and other 328-based boards       |--------------------------------|
 * |                                        | Interrupt No| 0  | 1  |                   |
 * |-------------------------------------------------------------------------------------|
 * |                                        |    Pin      | 2  | 3  | 21 | 20 | 19 | 18 |
 * |               Mega2560                 |--------------------------------------------|
 * |                                        | Interrupt No| 0  | 1  | 2  | 3  | 4  | 5  |
 * |-------------------------------------------------------------------------------------|
 * |                                        |    Pin      | 3  | 2  | 0  | 1  | 7  |    |
 * |    Leonardo and other 32u4-based boards |--------------------------------------------|
 * |                                        | Interrupt No| 0  | 1  | 2  | 3  | 4  |    |
 * |--------------------------------------------------------------------------------------
 * ---------------------------------------------------------------------------------------------------------------------------------------------
 *                 Correspondence table of micro:bit interrupt pins and terminal numbers
 * ---------------------------------------------------------------------------------------------------------------------------------------------
 * |             micro:bit                       | Digital Pin | P0-P20 can be used as external interrupt          |
 * |  (When used as an external interrupt,        |---------------------------------------------------------------------------------------------|
 * |  no need to set it to input mode with pinMode)| Interrupt No| Interrupt number is the pin's digital value, e.g., P0 interrupt number 0, P1 is 1 |
 * |-------------------------------------------------------------------------------------------------------------------------------------------|
 */

  Serial.println("Connect BMI323 INT1 to the defined MCU pin.");
  Serial.println("Every step will trigger an interrupt and update the counter.\n");
}

void loop() {
  if (gStepReady) {
    gStepReady = false;

    uint16_t status = bmi323.getIntStatus();
    if (status & BMI3_INT_STATUS_STEP_DETECTOR) {
      uint16_t steps = 0;
      if (bmi323.readStepCounter(&steps) == BMI3_OK) {
        Serial.print("Steps: ");
        Serial.println(steps);
      }
    }
  }
}

Result