Question

我正在使用带有MPU9255和BMP180的10 DOF IMU来收集方向数据。当我为arduino运行草图时，我下载它来测试IMU的功能，它可以完美地收集来自加速度计和陀螺仪元素的数据，但仍然无法从磁力计请求数据，而这是从未接收过的。它成功读取磁力计数据一次，但除非我重新上传程序，否则再也无法读取它。更具体地说，按位并且从不评估为真，因此程序无法继续，因为数据“未准备好”来自磁力计。令人讨厌的代码行是：

  do
  {
    I2Cread(MAG_ADDRESS,0x02,1,&ST1);
  }
  while (!(ST1&0x01));

但这是完整的代码，以防万一

#include <Wire.h>

#define    MPU9250_ADDRESS            0x68
#define    MAG_ADDRESS                0x0C

#define    GYRO_FULL_SCALE_250_DPS    0x00  
#define    GYRO_FULL_SCALE_500_DPS    0x08
#define    GYRO_FULL_SCALE_1000_DPS   0x10
#define    GYRO_FULL_SCALE_2000_DPS   0x18

#define    ACC_FULL_SCALE_2_G        0x00  
#define    ACC_FULL_SCALE_4_G        0x08
#define    ACC_FULL_SCALE_8_G        0x10
#define    ACC_FULL_SCALE_16_G       0x18



// This function read Nbytes bytes from I2C device at address Address. 
// Put read bytes starting at register Register in the Data array. 
void I2Cread(uint8_t Address, uint8_t Register, uint8_t Nbytes, uint8_t* Data)
{
  // Set register address
  Wire.beginTransmission(Address);
  Wire.write(Register);
  Wire.endTransmission();
 if(Register == 0x02){
   Serial.println("Data Not Ready");
 }
  // Read Nbytes
  Wire.requestFrom(Address, Nbytes); 
  uint8_t index=0;
  while (Wire.available())
    Data[index++]=Wire.read();
  Serial.println("Data: " + *Data); 
}


// Write a byte (Data) in device (Address) at register (Register)
void I2CwriteByte(uint8_t Address, uint8_t Register, uint8_t Data)
{
  // Set register address
  Wire.beginTransmission(Address);
  Wire.write(Register);
  Wire.write(Data);
  Wire.endTransmission();
}


// Initializations
void setup()
{
  // Arduino initializations
  Wire.begin();
  Serial.begin(115200);

  // Configure gyroscope range
  I2CwriteByte(MPU9250_ADDRESS,27,GYRO_FULL_SCALE_2000_DPS);
  // Configure accelerometers range
  I2CwriteByte(MPU9250_ADDRESS,28,ACC_FULL_SCALE_16_G);
  // Set by pass mode for the magnetometers
  I2CwriteByte(MPU9250_ADDRESS,0x37,0x02);

  // Request first magnetometer single measurement
  I2CwriteByte(MAG_ADDRESS,0x0A,0x01);


}


long int cpt=0;
// Main loop, read and display data
void loop()
{

  // _______________
  // ::: Counter :::

  // Display data counter
  Serial.println(cpt++,DEC);
  Serial.print ("\t");



  // ____________________________________
  // :::  accelerometer and gyroscope ::: 

  // Read accelerometer and gyroscope
  uint8_t Buf[14];
  I2Cread(MPU9250_ADDRESS,0x3B,14,Buf);


  // Create 16 bits values from 8 bits data

  // Accelerometer
  int16_t ax=-(Buf[0]<<8 | Buf[1]);
  int16_t ay=-(Buf[2]<<8 | Buf[3]);
  int16_t az=Buf[4]<<8 | Buf[5];

  // Gyroscope
  int16_t gx=-(Buf[8]<<8 | Buf[9]);
  int16_t gy=-(Buf[10]<<8 | Buf[11]);
  int16_t gz=Buf[12]<<8 | Buf[13];

    // Display values

  // Accelerometer
  Serial.print (ax,DEC); 
  Serial.print ("\t");
  Serial.print (ay,DEC);
  Serial.print ("\t");
  Serial.print (az,DEC);  
  Serial.print ("\t");

  // Gyroscope
  Serial.print (gx,DEC); 
  Serial.print ("\t");
  Serial.print (gy,DEC);
  Serial.print ("\t");
  Serial.print (gz,DEC);  
  Serial.print ("\t");


  // _____________________
  // :::  Magnetometer ::: 


  // Read register Status 1 and wait for the DRDY: Data Ready
 //Strong suspicion that this do while loop repeats to infinity
  uint8_t ST1;
  do
  {
    I2Cread(MAG_ADDRESS,0x02,1,&ST1);
    //Serial.println("Reading");
  }
  while (!(ST1&0x01)); 

  // Read magnetometer data  
  uint8_t Mag[7];  
  I2Cread(MAG_ADDRESS,0x03,7,Mag);


  // Create 16 bits values from 8 bits data

  // Magnetometer
  int16_t mx=-(Mag[3]<<8 | Mag[2]);
  int16_t my=-(Mag[1]<<8 | Mag[0]);
  int16_t mz=-(Mag[5]<<8 | Mag[4]);


  // Magnetometer
  Serial.print (mx+200,DEC); 
  Serial.print ("\t");
  Serial.print (my-70,DEC);
  Serial.print ("\t");
  Serial.print (mz-700,DEC);  
  Serial.print ("\t");



  // End of line
  Serial.println("");
  delay(100);    
}

Answer 1

啊哈，发现了实际问题：你需要为每一个新读数启动磁力计单次测量：

  // Create 16 bits values from 8 bits data

  // Magnetometer
  int16_t mx=-(Mag[3]<<8 | Mag[2]);
  int16_t my=-(Mag[1]<<8 | Mag[0]);
  int16_t mz=-(Mag[5]<<8 | Mag[4]);


  // Magnetometer
  Serial.print("MAG:\t");
  Serial.print (mx+200,DEC); 
  Serial.print ("\t");
  Serial.print (my-70,DEC);
  Serial.print ("\t");
  Serial.print (mz-700,DEC);  
  Serial.print ("\t");

  // Request first magnetometer single measurement !!!!!
  I2CwriteByte(MAG_ADDRESS,0x0A,0x01);

这是从代码的末尾开始，我添加了一行启动新的阅读。似乎在起作用。

Arduino传感器10DOF MPU9255无法获取磁力计数据

1 个答案: