Arduino Wire requestFrom冻结

Question

我正在尝试编写一个类来使用Arduino Wire库控制MPU6050，但是当我在我的Arduino mini中运行代码时，它在几秒钟后就冻结了。

下面是库的代码和测试草图：

// Include Wire Library for I2C
#include <Wire.h>

enum MPU6050_filter {_256Hz, _188Hz, _98Hz, _42Hz, _20Hz, _10Hz, _5Hz};
enum MPU6050_gyro {_250dps, _500dps, _1000dps, _2000dps};
enum MPU6050_accel {_2g, _4g, _8g, _16Hz};

class MPU6050
{
public:

  MPU6050 ();

  bool start (bool AD0_value);

  void goToSleep ();

  void stopSleeping ();

  void setFilterVal (MPU6050_filter filter_val);

  void setGyroRange (MPU6050_gyro range);

  void setAccelRange (MPU6050_accel range);

  bool dataAvailable ();

  void getLastGyroData (float& gx, float& gy, float& gz);

  void getRawGyroData (int& gx, int& gy, int& gz);

private:

  void writeRegister (byte address, byte data);

  byte readRegister (byte address);

  void readData (byte start_address, byte bytes, byte* data);

  float convertGyroToDPS (int gyro);

  bool AD0_val;
  MPU6050_filter filter;
  MPU6050_accel accel_range;
  MPU6050_gyro gyro_range;
  unsigned long last_read;
  const unsigned long min_read_time = 1;
};

MPU6050::MPU6050 () : AD0_val(false),
                      filter(_256Hz),
                      accel_range(_2g),
                      gyro_range(_250dps) {}

bool MPU6050::start (bool AD0_value)
{
  AD0_val = AD0_value;

  // init sample rate div to 0 (max sample rate)
  writeRegister(0x19, 0);
  // activate FIFO for gyroscope data
  writeRegister(0x23, 0x70);
  // clear config setup register
  writeRegister(0x6B, 0);

  // setup the register
  writeRegister(0x37, 0x10);
  // set interrupt by data ready
  writeRegister(0x38, 0x01);
}

void MPU6050::goToSleep ()
{
  byte prev_data = readRegister(0x6B);

  prev_data = (prev_data | 0x40);

  writeRegister(0x6B, prev_data);
}

void MPU6050::stopSleeping ()
{
  byte prev_data = readRegister(0x6B);

  prev_data = (prev_data & 0xBF);

  writeRegister(0x6B, prev_data);
}

void MPU6050::setFilterVal (MPU6050_filter filter_val)
{
  int val;

  if      (filter_val == _256Hz) val = 0;
  else if (filter_val == _188Hz) val = 1;
  else if (filter_val == _98Hz)  val = 2;
  else if (filter_val == _42Hz)  val = 3;
  else if (filter_val == _20Hz)  val = 4;
  else if (filter_val == _10Hz)  val = 5;
  else                           val = 6;
    
  byte data = readRegister(0x1A);
  data = (data & 0xF8) | (val & 0x07);
  writeRegister(0x1A, data);

  filter = filter_val;
}

void MPU6050::setAccelRange (MPU6050_accel range)
{
  byte value;

  if (range == _2g)      value = 0;
  else if (range == _4g) value = 1;
  else if (range == _8g) value = 2;
  else                   value = 3;

  byte reg_value = readRegister(0x1C);
  reg_value = (reg_value & 0xE0) | (value << 3);
  writeRegister(0x1C, reg_value);

  accel_range = range;
}

void MPU6050::setGyroRange (MPU6050_gyro range)
{
  byte value;

  if      (range == _250dps)  value = 0;
  else if (range == _500dps)  value = 1;
  else if (range == _1000dps) value = 2;
  else                        value = 3;

  byte reg_value = readRegister(0x1B);
  reg_value = (reg_value & 0xE0) | (value << 3);
  writeRegister(0x1B, reg_value);

  gyro_range = range;
}

bool MPU6050::dataAvailable ()
{
  return (readRegister(0x3A) & 0x01);
}

void MPU6050::getLastGyroData (float& gx, float& gy, float& gz)
{
  int raw_x, raw_y, raw_z;

  getRawGyroData(raw_x, raw_y, raw_z);

  gx = convertGyroToDPS(raw_x);
  gy = convertGyroToDPS(raw_y);
  gz = convertGyroToDPS(raw_z);
}

void MPU6050::getRawGyroData (int& gx, int& gy, int& gz)
{
  byte* data = new byte[6];
  
  readData(0x43, 6, data);
  
  gx = data[0] << 8 | data[1];
  gy = data[2] << 8 | data[3];
  gz = data[4] << 8 | data[5];

  delete data;
}

void MPU6050::writeRegister (byte address, byte data)
{
  Wire.beginTransmission(0x68 + AD0_val);
  Wire.write(address);
  Wire.write(data);
  Wire.endTransmission();
}

byte MPU6050::readRegister (byte address)
{
  byte data_buff = 0x00;

  Wire.beginTransmission(byte(0x68 + AD0_val));
  //Send the requested starting register                                      
  Wire.write(address);
  //End the transmission
  Wire.endTransmission(false);
  //Request 14 bytes from the MPU-6050                                  
  Wire.requestFrom(byte(0x68 + AD0_val), byte(0x01), byte(true));
  unsigned long initial_time = millis();
  //Wait until all the bytes are received
  while(Wire.available() == 0 and millis() < initial_time + 5);
  if (millis() < initial_time + 5)
  {
    // read the data
    data_buff = Wire.read();
  }
  // end the transmission
  Wire.endTransmission();

  return data_buff;
}

void MPU6050::readData (byte start_address, byte bytes, byte* data)
{
  Wire.beginTransmission(byte(0x68 + AD0_val));
  //Send the requested starting register
  Wire.write(start_address);
  //End the transmission
  Wire.endTransmission(false);
  //Request 14 bytes from the MPU-6050
  Wire.requestFrom(byte(0x68 + AD0_val), bytes, byte(true));
  //Wait until all the bytes are received
  while(Wire.available() < bytes);

  for (int i = 0; i < bytes; i++)
    data[i] = Wire.read();

  Wire.endTransmission();
}

float MPU6050::convertGyroToDPS (int gyro)
{
  if      (gyro_range == _250dps)  return float(gyro)/131.0;
  else if (gyro_range == _500dps)  return float(gyro)/65.5;
  else if (gyro_range == _1000dps) return float(gyro)/32.8;
  else                             return float(gyro)/16.4;
}



#define SHOW_EACH 50

MPU6050 chip;

unsigned long last_shown = 0;
unsigned this_fps = 0;
unsigned last_fps = 0;
unsigned last_time = 0;
unsigned total_fps = 0;

float g_x, g_y, g_z;

void setup()
{
  Serial.begin(115200);
  Serial.println("--------");
  chip.setFilterVal(_256Hz);
  chip.setGyroRange(_250dps);
  chip.start(false);
}

void loop()
{ 
  if (chip.dataAvailable())
    chip.getLastGyroData(g_x, g_y, g_z);
  
  ++this_fps;
  ++total_fps;

  if (millis()/1000 != last_time)
  {
    last_time = millis()/1000;
    last_fps = this_fps;
    this_fps = 0;
  }

  if (millis() - last_shown >= SHOW_EACH)
  {
    last_shown = millis();
    Serial.print(g_x);
    Serial.print(" ");
    Serial.print(g_y);
    Serial.print(" ");
    Serial.print(g_y);
    Serial.print(" ");
    Serial.print(last_fps);
    Serial.print(" ");
    Serial.println(total_fps);
  }
}

使用Serial.println进行的一些测试指向Wire库中的函数requestFrom。可能的原因是什么？

Answer 1

很抱歉，我写这篇文章作为回答，但我还不能写评论。

第一个。您的代码中有多个requestFrom()调用，因此最好指定问题发生的确切位置(如果可以)。

第二名。您完全确定是requestFrom()挂起了您的代码吗？在readData()中，在requestFrom()之后有一个while()。也许它挂在那里，因为另一个设备没有发送足够的字节(由于某些原因)。

无论如何，这可能会对(link)有一点帮助，这里他们建议总是检查endTransmission()的返回值。