Return to Answer

• Section 4.28, Register 107 – Power Management 1 PWR_MGMT_1, pages 40 to 41:

  Note:
  When using SPI interface, user should use DEVICE_RESET (register 107) as well as SIGNAL_PATH_RESET (register 104) to ensure the reset is performed properly. The sequence used should be:

  1. Set DEVICE_RESET = 1 (register PWR_MGMT_1)
  2. Wait 100ms
  3. Set GYRO_RESET = ACCEL_RESET = TEMP_RESET = 1 (register SIGNAL_PATH_RESET)
  4. Wait 100ms

• Section 4.26, Register 104 – Signal Path Reset SIGNAL_PATH_RESET, page 37:

  Note: This register does not clear the sensor registers. The reset initializes the serial interface as well.

void initializeSensor()
{
  //
  // Perfrom full reset as per MPU-6000/MPU-6050 Register Map and Descriptions, Section 4.28, pages 40 to 41.
  //

  // performing full device reset, disables temperature sensor, disables SLEEP mode
  Wire.beginTransmission(0x68);  // Device address.
  Wire.write(0x6B);              // PWR_MGMT_1 register.
  Wire.write(0b10001000);        // DEVICE_RESET, TEMP_DIS.
  Wire.endTransmission();
  delay(100);                    // Wait for reset to complete.

  Wire.beginTransmission(0x68);  // Device address.
  Wire.write(0x68);              // SIGNAL_PATH_RESET register.
  Wire.write(0b00000111);        // GYRO_RESET, ACCEL_RESET, TEMP_RESET.
  Wire.endTransmission();
  delay(100);                    // Wait for reset to complete.
}

1. Modified readGyro() to implement 3 states (Request, Wait, and Read) and return true when 6 bytes have been read from the MPU-6050.

2. Added Blink Without Delay to loop() to see whether the MCU freezes which requires changing the ADO pin from pin 13 (the built-in led) to another pin, i.e. pin 12.

3. Added several Serial.print() statements for debugging to see where things go wrong.

#include <Wire.h>

const byte IMUAddress = 0x68;
const byte addressPin = 12;     // Changed from 13 to 12 because 13 is built-in LED.

int gyroX, gyroY, gyroZ;

void setup()
{
  Wire.begin();
  Serial.begin(115200);
  Serial.println(F("\n\nMPU-6050 Test\n"));

  //designating pins as I/O
  pinMode(addressPin, OUTPUT);
  pinMode(LED_BUILTIN, OUTPUT);  // Added LED for heartbeat signal.

  //setting IMU address to 0x68 (LOW)
  digitalWrite(addressPin, IMUAddress & 1);

  initializeSensor();
}

void loop()
{
  //
  // TASK 1: Blink without delay to indicate that MCU hasn't frozen.
  //
  const unsigned int INTERVAL = 250;
  unsigned long current_timestamp = millis();
  static unsigned long previous_timestamp = current_timestamp;
  static bool led_state = false;
  if (current_timestamp - previous_timestamp >= INTERVAL)
  {
    led_state = !led_state;
    digitalWrite(LED_BUILTIN, led_state);
    previous_timestamp += INTERVAL;
  }

  //
  // TASK 2: Read gyro.
  //
  if (readGyro())
  {
    Serial.print(gyroX);
    Serial.print(F("    "));
    Serial.print(gyroY);
    Serial.print(F("    "));
    Serial.println(gyroZ);
  }
}

void initializeSensor()
{
  //
  // Perform full reset as per MPU-6000/MPU-6050 Register Map and Descriptions, Section 4.28, pages 40 to 41.
  //

  // performing full device reset, disables temperature sensor, disables SLEEP mode
  Serial.print(F("Performing full reset of MPU-6000..."));

  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x6B);                     // PWR_MGMT_1 register.
  Wire.write(0b10001000);               // DEVICE_RESET, TEMP_DIS.
  Wire.endTransmission();
  delay(100);                           // Wait for reset to complete.

  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x68);                     // SIGNAL_PATH_RESET register.
  Wire.write(0b00000111);               // GYRO_RESET, ACCEL_RESET, TEMP_RESET.
  Wire.endTransmission();
  delay(100);                           // Wait for reset to complete.

  Serial.println(F(" Done."));

  //
  // Writing to gyro config register.
  //
  Serial.print(F("Configuring gyro..."));
  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x1B);                     // GYRO_CONFIG register.
  Wire.write(0b00001000);               // +/-500 deg/s.
  Wire.endTransmission();
  Serial.println(F(" Done."));
}

typedef enum State
{
  Request,
  Wait,
  Read
};

bool readGyro()
{
  static State state = State::Request;

  switch (state)
  {
    case State::Request:
      // Request data from gyro data registers.
      Serial.print(F("Requesting data from gyro..."));
      Wire.beginTransmission(IMUAddress);   // Device address.
      Wire.write(0x43);                     // GYRO_XOUT_H register.
      Wire.endTransmission();
      Wire.requestFrom(IMUAddress, 6);      // GYRO_XOUT_H, GYRO_XOUT_L, GYRO_YOUT_H, GYRO_YOUT_L, GYRO_ZOUT_H, GYRO_ZOUT_L.
      Serial.println(F(" Done."));
      state = State::Wait;
      Serial.print(F("Waiting for data from gyro"));
      break;

    case State::Wait:
      // Wait for data to arrive into buffer.
      if(Wire.available() < 6)
      {
        Serial.print(F("."));
      }
      else
      {
        Serial.println(F(" Done."));
        state = State::Read;
      }
      break;

    case State::Read:
      // Read data from gyro registers.
      Serial.print(F("Reading gyro data..."));
      gyroX = Wire.read() << 8 | Wire.read();
      gyroY = Wire.read() << 8 | Wire.read();
      gyroZ = Wire.read() << 8 | Wire.read();
      Serial.println(F(" Done."));
      state = State::Request;
      return true;  // Indicate data was received.
      break;
  }

  return false;  // Indicate no data received yet.
}

This will require level shifters on the signals between the 3.3 V MPU-6050 and the 5 V Arduino.

• Section 4.28, Register 107 – Power Management 1 PWR_MGMT_1, pages 40 to 41:

  Note:
  When using SPI interface, user should use DEVICE_RESET (register 107) as well as SIGNAL_PATH_RESET (register 104) to ensure the reset is performed properly. The sequence used should be:

  1. Set DEVICE_RESET = 1 (register PWR_MGMT_1)
  2. Wait 100ms
  3. Set GYRO_RESET = ACCEL_RESET = TEMP_RESET = 1 (register SIGNAL_PATH_RESET)
  4. Wait 100ms

• Section 4.26, Register 104 – Signal Path Reset SIGNAL_PATH_RESET, page 37:

  Note: This register does not clear the sensor registers. The reset initializes the serial interface as well.

• Section 3, Register Map, page 8:

  The reset value is 0x00 for all registers other than the registers below.

  • Register 107: 0x40.
  • Register 117: 0x68.

This means that the PWR_MGMT_1 register defaults to sleep mode after a reset so it needs to be rewritten to disable sleep mode after commanding a reset.

void initializeSensor()
{
  //
  // Perfrom full reset as per MPU-6000/MPU-6050 Register Map and Descriptions, Section 4.28, pages 40 to 41.
  //

  // performing full device reset, disables temperature sensor, disables SLEEP mode
  Wire.beginTransmission(0x68);  // Device address.
  Wire.write(0x6B);              // PWR_MGMT_1 register.
  Wire.write(0b10001000);        // DEVICE_RESET, TEMP_DIS.
  Wire.endTransmission();
  delay(100);                    // Wait for reset to complete.

  Wire.beginTransmission(0x68);  // Device address.
  Wire.write(0x68);              // SIGNAL_PATH_RESET register.
  Wire.write(0b00000111);        // GYRO_RESET, ACCEL_RESET, TEMP_RESET.
  Wire.endTransmission();
  delay(100);                    // Wait for reset to complete. 

  // Disable SLEEP mode because the reset re-enables it. Section 3, PWR_MGMT_1 register, page 8.
  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x6B);                     // PWR_MGMT_1 register.
  Wire.write(0b00001000);               // SLEEP = 0, TEMP_DIS = 1.
  Wire.endTransmission();
}

1. Modified readGyro() to implement 3 states (Request, Wait, and Read) and return true when 6 bytes have been read from the MPU-6050.

2. Added Blink Without Delay to loop() to see whether the MCU freezes which requires changing the ADO pin from pin 13 (the built-in led) to another pin, i.e. pin 12.

3. Added several Serial.print() statements for debugging to see where things go wrong.

4. Tweaked the code in response to comments.

#include <Wire.h>

const byte IMUAddress = 0x68;   // Added for readability and maintainability.
const byte addressPin = 12;     // Changed from 13 to 12 because 13 is built-in LED.

int gyroX, gyroY, gyroZ;

void setup()
{
  Wire.begin();
  Serial.begin(115200);
  Serial.println(F("\n\nMPU-6050 Test\n"));

  // Designating pins as I/O.
  pinMode(addressPin, OUTPUT);
  pinMode(LED_BUILTIN, OUTPUT);  // Added LED for heartbeat signal.

  // Setting IMU address to 0x68 (LOW).
  digitalWrite(addressPin, IMUAddress & 1);  // Added bit mask of bit 0.

  initializeSensor();
}

void loop()
{
  //
  // TASK 1: Blink without delay to indicate that MCU hasn't frozen.
  //
  const unsigned int INTERVAL = 250;
  unsigned long current_timestamp = millis();
  static unsigned long previous_timestamp = current_timestamp;
  static bool led_state = false;
  if (current_timestamp - previous_timestamp >= INTERVAL)
  {
    led_state = !led_state;
    digitalWrite(LED_BUILTIN, led_state);
    previous_timestamp += INTERVAL;
  }

  //
  // TASK 2: Read gyro.
  //
  if (readGyro())
  {
    Serial.print(gyroX);
    Serial.print(F("    "));
    Serial.print(gyroY);
    Serial.print(F("    "));
    Serial.println(gyroZ);
  }
}

void initializeSensor()
{
  //
  // Perform full reset as per MPU-6000/MPU-6050 Register Map and Descriptions, Section 4.28, pages 40 to 41.
  //

  Serial.print(F("Performing full reset of MPU-6050..."));

  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x6B);                     // PWR_MGMT_1 register.
  Wire.write(0b10001000);               // DEVICE_RESET, TEMP_DIS.
  Wire.endTransmission();
  delay(100);                           // Wait for reset to complete.

  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x68);                     // SIGNAL_PATH_RESET register.
  Wire.write(0b00000111);               // GYRO_RESET, ACCEL_RESET, TEMP_RESET.
  Wire.endTransmission();
  delay(100);                           // Wait for reset to complete.

  Serial.println(F(" Done."));

  // Disable SLEEP mode because the reset re-enables it. Section 3, PWR_MGMT_1 register, page 8.
  Serial.print(F("Disabling sleep mode of MPU-6050..."));
  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x6B);                     // PWR_MGMT_1 register.
  Wire.write(0b00001000);               // SLEEP = 0, TEMP_DIS = 1.
  Wire.endTransmission();
  Serial.println(F(" Done."));

  //
  // Writing to gyro config register.
  //
  Serial.print(F("Configuring gyro of MPU-6050..."));
  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x1B);                     // GYRO_CONFIG register.
  Wire.write(0b00001000);               // +/-500 deg/s.
  Wire.endTransmission();
  Serial.println(F(" Done."));
}

typedef enum State
{
  Request,
  Wait,
  Read
};

bool readGyro()
{
  static State state = State::Request;

  switch (state)
  {
    case State::Request:
      // Request data from gyro data registers.
      Serial.print(F("Requesting data from gyro..."));
      Wire.beginTransmission(IMUAddress);   // Device address.
      Wire.write(0x43);                     // GYRO_XOUT_H register.
      Wire.endTransmission(false);          // Restart connection, i.e. keep alive.
      Wire.requestFrom(IMUAddress, 6);      // GYRO_XOUT_H, GYRO_XOUT_L, GYRO_YOUT_H, GYRO_YOUT_L, GYRO_ZOUT_H, GYRO_ZOUT_L.
      Serial.println(F(" Done."));
      state = State::Wait;
      Serial.print(F("Waiting for data from gyro..."));
      break;

    case State::Wait:
      // Wait for data to arrive into buffer.
      if(Wire.available() < 6)
      {
        //Serial.print(F("."));
        Serial.print(F(" "));
        Serial.print(Wire.available());  // Added to show bytes received.
      }
      else
      {
        Serial.print(F(" "));
        Serial.print(Wire.available());  // Added to show bytes received.
        Serial.println(F(" Done."));
        state = State::Read;
      }
      break;

    case State::Read:
      // Read data from gyro registers.
      Serial.print(F("Reading gyro data..."));
      gyroX = Wire.read() << 8 | Wire.read();
      gyroY = Wire.read() << 8 | Wire.read();
      gyroZ = Wire.read() << 8 | Wire.read();
      Serial.println(F(" Done."));
      state = State::Request;
      return true;  // Indicate data was received.
      break;
  }

  return false;  // Indicate no data received yet.
}

This will require level shifters on the signals between the 3.3 V MPU-6050 and the 5 V Arduino.

• Section 4.28, Register 107 – Power Management 1 PWR_MGMT_1, pages 40 to 41:

  Note:
  When using SPI interface, user should use DEVICE_RESET (register 107) as well as SIGNAL_PATH_RESET (register 104) to ensure the reset is performed properly. The sequenceused should be:

  1. Set DEVICE_RESET = 1 (register PWR_MGMT_1)
  2. Wait 100ms
  3. Set GYRO_RESET = ACCEL_RESET = TEMP_RESET = 1 (register SIGNAL_PATH_RESET)
  4. Wait 100ms

• Section 4.26, Register 104 – Signal Path Reset SIGNAL_PATH_RESET, page 37:

  Note: This register does not clear the sensor registers. The reset initializes the serial interface as well.

• Section 4.28, Register 107 – Power Management 1 PWR_MGMT_1, pages 40 to 41:

  Note:
  When using SPI interface, user should use DEVICE_RESET (register 107) as well as SIGNAL_PATH_RESET (register 104) to ensure the reset is performed properly. The sequence used should be:

  1. Set DEVICE_RESET = 1 (register PWR_MGMT_1)
  2. Wait 100ms
  3. Set GYRO_RESET = ACCEL_RESET = TEMP_RESET = 1 (register SIGNAL_PATH_RESET)
  4. Wait 100ms

• Section 4.26, Register 104 – Signal Path Reset SIGNAL_PATH_RESET, page 37:

  Note: This register does not clear the sensor registers. The reset initializes the serial interface as well.

Update based upon RowanP's answer

While concentrating on the software issues I missed a crucial piece of information from the other datasheet (MPU-6000/MPU-6050 Product Specification), i.e. the electrical characteristics in Sections 6.3 and 6.4 on pages 14 and 15 showing a Vdd range of 2.375 V to 3.46 V:

6.4 Electrical Specifications, Continued

This will require level shifters on the signals between the 3.3 V MPU-6050 and the 5 V Arduino.

From the MPU-6000/MPU-6050 Register Map and Descriptions, Section 4.28, pages 40 to 41:

Note: When using SPI interface, user should use DEVICE_RESET (register 107) as well as SIGNAL_PATH_RESET (register 104) to ensure the reset is performed properly. The sequenceused should be:

1. Set DEVICE_RESET = 1 (register PWR_MGMT_1)
2. Wait 100ms
3. Set GYRO_RESET = ACCEL_RESET = TEMP_RESET = 1 (register SIGNAL_PATH_RESET)
4. Wait 100ms

Section 4.26 (page 37) 4.26 Register 104 – Signal Path Reset SIGNAL_PATH_RESET

void initializeSensor()
{
  //
  // Perfrom full reset as per MPU-6000/MPU-6050 Register Map and Descriptions, Section 4.28, pages 40 to 41.
  //

  // performing full device reset, disables temperature sensor, disables SLEEP mode
  Wire.beginTransmission(0x68);  // Device address.
  Wire.write(0x6B);              // PWR_MGMT_1 register.
  Wire.write(0b10001000);        // DEVICE_RESET, TEMP_DIS.
  Wire.endTransmission();
  delay(100);                    // Wait for reset to complete.

  Wire.beginTransmission(0x68);  // Device address.
  Wire.write(0x68);              // SIGNAL_PATH_RESET register.
  Wire.write(0b00000111);        // GYRO_RESET, ACCEL_RESET, TEMP_RESET.
  Wire.endTransmission();
  delay(100);                    // Wait for reset to complete.
}

From the MPU-6000/MPU-6050 Register Map and Descriptions:

• Section 4.28, Register 107 – Power Management 1 PWR_MGMT_1, pages 40 to 41:

  Note:
  When using SPI interface, user should use DEVICE_RESET (register 107) as well as SIGNAL_PATH_RESET (register 104) to ensure the reset is performed properly. The sequenceused should be:

  1. Set DEVICE_RESET = 1 (register PWR_MGMT_1)
  2. Wait 100ms
  3. Set GYRO_RESET = ACCEL_RESET = TEMP_RESET = 1 (register SIGNAL_PATH_RESET)
  4. Wait 100ms

• Section 4.26, Register 104 – Signal Path Reset SIGNAL_PATH_RESET, page 37:

  Note: This register does not clear the sensor registers. The reset initializes the serial interface as well.

void initializeSensor()
{
  //
  // Perfrom full reset as per MPU-6000/MPU-6050 Register Map and Descriptions, Section 4.28, pages 40 to 41.
  //

  // performing full device reset, disables temperature sensor, disables SLEEP mode
  Wire.beginTransmission(0x68);  // Device address.
  Wire.write(0x6B);              // PWR_MGMT_1 register.
  Wire.write(0b10001000);        // DEVICE_RESET, TEMP_DIS.
  Wire.endTransmission();
  delay(100);                    // Wait for reset to complete.

  Wire.beginTransmission(0x68);  // Device address.
  Wire.write(0x68);              // SIGNAL_PATH_RESET register.
  Wire.write(0b00000111);        // GYRO_RESET, ACCEL_RESET, TEMP_RESET.
  Wire.endTransmission();
  delay(100);                    // Wait for reset to complete.
}

In the following code I've:

1. Modified readGyro() to implement 3 states (Request, Wait, and Read) and return true when 6 bytes have been read from the MPU-6050.

2. Added Blink Without Delay to loop() to see whether the MCU freezes which requires changing the ADO pin from pin 13 (the built-in led) to another pin, i.e. pin 12.

3. Added several Serial.print() statements for debugging to see where things go wrong.

#include <Wire.h>

const byte IMUAddress = 0x68;
const byte addressPin = 12;     // Changed from 13 to 12 because 13 is built-in LED.

int gyroX, gyroY, gyroZ;

void setup()
{
  Wire.begin();
  Serial.begin(115200);
  Serial.println(F("\n\nMPU-6050 Test\n"));

  //designating pins as I/O
  pinMode(addressPin, OUTPUT);
  pinMode(LED_BUILTIN, OUTPUT);  // Added LED for heartbeat signal.

  //setting IMU address to 0x68 (LOW)
  digitalWrite(addressPin, IMUAddress & 1);

  initializeSensor();
}

void loop()
{
  //
  // TASK 1: Blink without delay to indicate that MCU hasn't frozen.
  //
  const unsigned int INTERVAL = 250;
  unsigned long current_timestamp = millis();
  static unsigned long previous_timestamp = current_timestamp;
  static bool led_state = false;
  if (current_timestamp - previous_timestamp >= INTERVAL)
  {
    led_state = !led_state;
    digitalWrite(LED_BUILTIN, led_state);
    previous_timestamp += INTERVAL;
  }

  //
  // TASK 2: Read gyro.
  //
  if (readGyro())
  {
    Serial.print(gyroX);
    Serial.print(F("    "));
    Serial.print(gyroY);
    Serial.print(F("    "));
    Serial.println(gyroZ);
  }
}

void initializeSensor()
{
  //
  // Perform full reset as per MPU-6000/MPU-6050 Register Map and Descriptions, Section 4.28, pages 40 to 41.
  //

  // performing full device reset, disables temperature sensor, disables SLEEP mode
  Serial.print(F("Performing full reset of MPU-6000..."));

  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x6B);                     // PWR_MGMT_1 register.
  Wire.write(0b10001000);               // DEVICE_RESET, TEMP_DIS.
  Wire.endTransmission();
  delay(100);                           // Wait for reset to complete.

  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x68);                     // SIGNAL_PATH_RESET register.
  Wire.write(0b00000111);               // GYRO_RESET, ACCEL_RESET, TEMP_RESET.
  Wire.endTransmission();
  delay(100);                           // Wait for reset to complete.

  Serial.println(F(" Done."));

  //
  // Writing to gyro config register.
  //
  Serial.print(F("Configuring gyro..."));
  Wire.beginTransmission(IMUAddress);   // Device address.
  Wire.write(0x1B);                     // GYRO_CONFIG register.
  Wire.write(0b00001000);               // +/-500 deg/s.
  Wire.endTransmission();
  Serial.println(F(" Done."));
}

typedef enum State
{
  Request,
  Wait,
  Read
};

bool readGyro()
{
  static State state = State::Request;

  switch (state)
  {
    case State::Request:
      // Request data from gyro data registers.
      Serial.print(F("Requesting data from gyro..."));
      Wire.beginTransmission(IMUAddress);   // Device address.
      Wire.write(0x43);                     // GYRO_XOUT_H register.
      Wire.endTransmission();
      Wire.requestFrom(IMUAddress, 6);      // GYRO_XOUT_H, GYRO_XOUT_L, GYRO_YOUT_H, GYRO_YOUT_L, GYRO_ZOUT_H, GYRO_ZOUT_L.
      Serial.println(F(" Done."));
      state = State::Wait;
      Serial.print(F("Waiting for data from gyro"));
      break;

    case State::Wait:
      // Wait for data to arrive into buffer.
      if(Wire.available() < 6)
      {
        Serial.print(F("."));
      }
      else
      {
        Serial.println(F(" Done."));
        state = State::Read;
      }
      break;

    case State::Read:
      // Read data from gyro registers.
      Serial.print(F("Reading gyro data..."));
      gyroX = Wire.read() << 8 | Wire.read();
      gyroY = Wire.read() << 8 | Wire.read();
      gyroZ = Wire.read() << 8 | Wire.read();
      Serial.println(F(" Done."));
      state = State::Request;
      return true;  // Indicate data was received.
      break;
  }

  return false;  // Indicate no data received yet.
}