与 BMI270 进行辅助 I2C 通信时遇到困难

Question

我有一个使用 BMI270 和 LIS2MDL 磁力计的分线板，lis2MDL SDA 和 SCL 引脚通过 BMI270 的 ASCX 和 ASDX 引脚连接。本质上使其成为 BMI270 的从设备。 BMI270 使用地址 0x68，这也应该是我与 LIS2MDL 通信的相同地址。但是，我在与 LIS2MDL 实际通信时遇到问题，但在与 IMU 通信时没有问题。在本 PDF 的第 60 页上，它介绍了通过 I2C 进行的辅助通信：

https://www.lcsc.com/datasheet/lcsc_datasheet_2207152130_Bosch-Sensortec-BMI270_C2836813.pdf

此时我非常困惑和迷失。下面是我的 Arduino 代码的一部分，最后的打印语句应该是 LIS2MDL 的芯片 ID，但是，我只得到“42”，这不应该是它。这表明我可能没有与传感器通信。此外，当我尝试从传感器获取值时，我得到“16962”但不会更新。

以下是代码：

// I2C addresses
#define BMI270_ADDR 0x68   // I2C address of BMI270
#define LIS2MDL_ADDR 0x1E  // Default I2C address of LIS2MDL (on auxiliary bus)

// BMI270 Register Addresses
#define BMI270_AUX_CONFIG 0x4B  // Auxiliary I2C configuration register
#define BMI270_AUX_WRITE 0x4C   // Write to auxiliary device (LIS2MDL)
#define BMI270_AUX_READ 0x4D    // Read from auxiliary device (LIS2MDL)
#define BMI270_CTRL 0x7E        // Control register for sensor modes
#define BMI270_AUX_EN 0x44      // Auxiliary I2C enable

// LIS2MDL Register Addresses
#define LIS2MDL_WHO_AM_I 0x4F   // WHO_AM_I register to verify sensor identity
#define LIS2MDL_OUTX_L  0x68    // Output registers for magnetometer data

#define SDA_PIN 21  // Define your SDA pin
#define SCL_PIN 26  // Define your SCL pin

// Variables to hold sensor data
int16_t magX, magY, magZ;

void setup() {
  Wire.begin(SDA_PIN, SCL_PIN);    // Start I2C communication for ESP32

  Serial.begin(115200);  // Start serial communication for debugging

  delay(1000);

  // Initialize BMI270 (primary sensor)
  initBMI270();

  // Enable auxiliary I2C to communicate with LIS2MDL
  enableAuxiliaryI2C();

  // Check communication with LIS2MDL (WHO_AM_I)
  uint8_t whoAmI = readAuxRegister(LIS2MDL_WHO_AM_I);
  if (whoAmI == 0x40) {  // Expected WHO_AM_I response from LIS2MDL
    Serial.println("LIS2MDL communication successful!");
  } else {
    Serial.print("LIS2MDL communication failed, WHO_AM_I: ");
    Serial.println(whoAmI, HEX);
  }
}

void loop() {
  // Read magnetometer data from LIS2MDL through the BMI270
  readMagnetometerData();
  Serial.print("Magnetometer X: "); Serial.println(magX);
  Serial.print("Magnetometer Y: "); Serial.println(magY);
  Serial.print("Magnetometer Z: "); Serial.println(magZ);
  delay(1000);  // Wait before reading again
}

// Function to initialize the BMI270
void initBMI270() {
  // Put BMI270 into configuration mode
  writeRegister(BMI270_ADDR, BMI270_CTRL, 0x00);  // Placeholder configuration mode
  delay(10);

  // Additional setup if required (e.g., accelerometer or gyroscope config)
  Serial.println("BMI270 initialized.");
}

// Function to enable the auxiliary I2C on the BMI270
void enableAuxiliaryI2C() {
  // Enable auxiliary I2C in BMI270 to talk to LIS2MDL
  writeRegister(BMI270_ADDR, BMI270_AUX_CONFIG, 0x01);  // Enable AUX I2C mode
  delay(10);  // Allow time for configuration
  Serial.println("Auxiliary I2C enabled.");
}

// Function to read magnetometer data from LIS2MDL
void readMagnetometerData() {
  uint8_t data[6];
  
  // Read 6 bytes from LIS2MDL (magnetometer output)
  for (int i = 0; i < 6; i++) {
    data[i] = readAuxRegister(LIS2MDL_OUTX_L + i);
  }

  // Combine bytes into 16-bit integers (LSB first)
  magX = (int16_t)(data[1] << 8 | data[0]);
  magY = (int16_t)(data[3] << 8 | data[2]);
  magZ = (int16_t)(data[5] << 8 | data[4]);
}

// Helper function to write to BMI270 register
void writeRegister(uint8_t address, uint8_t reg, uint8_t value) {
  Wire.beginTransmission(address);
  Wire.write(reg);
  Wire.write(value);
  Wire.endTransmission();
}

// Helper function to read from BMI270's auxiliary I2C bus (LIS2MDL)
uint8_t readAuxRegister(uint8_t reg) {
  // Set the register to read from in the auxiliary device (LIS2MDL)
  writeRegister(BMI270_ADDR, BMI270_AUX_WRITE, reg);
  delay(10);  // Wait for the register to be set

  // Read the result from the auxiliary read register of BMI270
  Wire.beginTransmission(BMI270_ADDR);
  Wire.write(BMI270_AUX_READ);
  Wire.endTransmission(false);
  Wire.requestFrom(BMI270_ADDR, 1);

  if (Wire.available()) {
    return Wire.read();
  }
  return 0xFF;  // Return an invalid value if communication failed
}

我尝试对两个传感器使用预制库的组合，甚至制作了一些自定义 I2C 代码，老实说，我从未这样做过。所以我确实使用 ChatGPT 来寻求帮助。每次，我根本无法与磁力计通信，但能够与陀螺仪通信。

Answer 1

在Arduino示例中，有一个名为i2c_scanner的示例，运行它并检查串行监视器中是否出现两个地址。