MPU6050 Accelerometer + Gyroscope Complete Guide

The MPU6050 is a six-axis motion sensor from InvenSense (now TDK): a 3-axis gyroscope and a 3-axis accelerometer in one 4 × 4 × 0.9 mm chip, with a Digital Motion Processor (DMP) and a 1024-byte FIFO. It is usually sold on the purple GY-521 breakout. It tells you how a thing is tilted and how fast it turns, which makes it the basis of self-balancing robots, gimbals, drones and gesture projects.

This guide covers the real specifications from the InvenSense datasheet and register map, the pins of the GY-521 board, the I2C addresses, wiring, code with raw registers, calibration, and the traps that give drifting or wrong readings. The chip data comes from the MPU-6000/MPU-6050 product specification and register map (InvenSense). The board pins describe the common GY-521, and other boards may differ.

What is in the chip

The MPU6050 does not have a magnetometer, so it cannot give an absolute compass heading. For a nine-axis solution look at the BNO055, which does sensor fusion on the chip.

Source: InvenSense MPU-6000/MPU-6050 product specification.

Getting started

Specifications

Sensor chip

GY-521 breakout (typical)

Source: InvenSense MPU-6000/MPU-6050 product specification. The GY-521 data is typical and differs between sellers.

Dimensions

The chip is a QFN package of 4 × 4 mm and 0.9 mm high. The GY-521 breakout is a small board of roughly 21 × 16 mm in many shops, but sizes vary, so measure yours before you design a mount. Orientation matters: the chip has X, Y and Z axes marked in the datasheet, and the printed arrows on your board tell you which way is which.

Source: package size from the InvenSense datasheet. The board size is not from a datasheet.

Pins of the GY-521

The order and the pull-ups differ between boards, so check yours. Most GY-521 boards have pull-up resistors on SDA and SCL.

Source: InvenSense MPU-6000/MPU-6050 product specification, pin functions. The GY-521 layout is typical.

Wiring

The chip runs at 3.46 V at most. The board has a regulator, but its I2C pull-ups may go to VCC, so with 5 V on VCC the SDA and SCL lines also swing to 5 V. For a 3.3 V ESP32, power the board from 3.3 V.

Software setup

Read the sensor

#include <Wire.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>

Adafruit_MPU6050 mpu;

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);
  if (!mpu.begin()) {
    Serial.println("Failed to find MPU6050");
    while (1) delay(10);
  }
  mpu.setAccelerometerRange(MPU6050_RANGE_8_G);
  mpu.setGyroRange(MPU6050_RANGE_500_DEG);
}

void loop() {
  sensors_event_t a, g, temp;
  mpu.getEvent(&a, &g, &temp);

  Serial.print("Accel (m/s^2): ");
  Serial.print(a.acceleration.x); Serial.print(", ");
  Serial.print(a.acceleration.y); Serial.print(", ");
  Serial.println(a.acceleration.z);

  Serial.print("Gyro (rad/s): ");
  Serial.print(g.gyro.x); Serial.print(", ");
  Serial.print(g.gyro.y); Serial.print(", ");
  Serial.println(g.gyro.z);

  delay(200);
}

I did not run this sketch on a board, it follows the library example.

Reading the registers yourself

You do not need a library to read the MPU6050. Wake the chip (it starts in sleep mode), then read 14 bytes from 0x3B: accelerometer X, Y, Z, temperature and gyroscope X, Y, Z, each a signed 16-bit value, high byte first.

#include <Wire.h>
#define MPU 0x68

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);
  Wire.beginTransmission(MPU);
  Wire.write(0x6B); Wire.write(0x00);     // PWR_MGMT_1: clear the sleep bit
  Wire.endTransmission();
  Wire.beginTransmission(MPU);
  Wire.write(0x75); Wire.endTransmission(false);
  Wire.requestFrom(MPU, 1);
  Serial.printf("WHO_AM_I = 0x%02X (expect 0x68)n", Wire.read());
}

void loop() {
  Wire.beginTransmission(MPU);
  Wire.write(0x3B); Wire.endTransmission(false);
  Wire.requestFrom(MPU, 14);
  int16_t v[7];
  for (int i = 0; i < 7; i++) v[i] = (Wire.read() << 8) | Wire.read();
  float ax = v[0] / 16384.0f, ay = v[1] / 16384.0f, az = v[2] / 16384.0f;   // g, range +-2 g
  float tc = v[3] / 340.0f + 36.53f;                                          // degC
  float gx = v[4] / 131.0f,  gy = v[5] / 131.0f,  gz = v[6] / 131.0f;       // deg/s, range +-250
  Serial.printf("a %.2f %.2f %.2f g  g %.1f %.1f %.1f dps  %.1f Cn", ax, ay, az, gx, gy, gz, tc);
  delay(100);
}

Registers

The sketch has not been run on a board. Use 16384 as the divisor for the ±2 g range, and 131 for the ±250 °/s range. If you change the range with the config registers, use the matching sensitivity from the specification table.

Source: InvenSense MPU-6000/MPU-6050 register map and product specification.

Calibration and angles

Raw readings are not zero at rest, so you have to calibrate:

• Gyro offset. Keep the board still, average a few hundred gyroscope readings, and subtract that offset. The zero-rate offset can be up to ±20 °/s over temperature.
• Accelerometer offset. With the board flat, Z should read 1 g and X and Y 0 g. Correct the difference.
• Tilt from the accelerometer. Roll = atan2(ay, az) and pitch = atan2(−ax, sqrt(ay² + az²)). It is stable over time but noisy when the board moves.
• Angle from the gyroscope. Integrate the rate over time. It is smooth but drifts.
• Combine them. A complementary or Kalman filter blends both: angle = 0.98 × (angle + gyro × dt) + 0.02 × accel angle.
• No yaw from the accelerometer. Without a magnetometer the heading drifts. The DMP and a magnetometer on the auxiliary port can help.

Source: InvenSense datasheet for the offsets. The angle formulas are standard and not from the datasheet.

Getting stable readings

• Mount it rigidly. A loose board picks up vibration as noise.
• Keep it away from motors and magnets. The chip has no magnetometer, but a vibrating motor shakes the accelerometer.
• Choose the lowest range that fits. ±2 g and ±250 °/s give the best resolution. Use larger ranges only when you need them.
• Set the digital low-pass filter in CONFIG to reduce noise at the cost of delay.
• Use the INT pin. Read data when the sensor says it is ready, not on a fixed delay.
• Wait after power-up. Let the sensor warm up for a few seconds before you calibrate.
• Let the temperature settle before a calibration, because the offsets change with temperature.

Real gotchas

• It starts in sleep mode. You must write 0 to PWR_MGMT_1 (0x6B), or every reading is zero.
• The chip is a 3.3 V part. VDD is 2.375 to 3.46 V. Only the regulated GY-521 board takes 5 V on VCC.
• Two addresses. AD0 low is 0x68, high is 0x69. A fake chip (marked MPU6050 but a clone) can answer with a different WHO_AM_I, so check it.
• Gyroscope drift. Integrating gives an angle that drifts. Always combine it with the accelerometer.
• No heading. The MPU6050 has no magnetometer.
• Orientation of the axes. Follow the arrows printed on the board and the datasheet, not your assumption.
• Wrong scale factor. The divisor depends on the range you set. Using 16384 after you set ±8 g gives values four times too large.
• I2C speed. The chip runs at 400 kHz at most. Keep the wires short, because the GY-521 pull-ups are often weak.
• Temperature is for compensation. The built-in temperature value is not an accurate room thermometer.

Compared with other motion sensors

The ADXL345 row is general knowledge and not from a datasheet read for this guide.

What to build with it

• Tilt/orientation sensing: self-balancing robots, gimbals.
• Step counting / activity detection: wearable projects.
• Vibration/impact detection: accelerometer-only use cases.
• Drone/RC flight controllers: a common low-cost IMU choice for hobby builds.

• A self-balancing robot with a PID loop on the tilt angle.
• A motion-triggered light that wakes up when the board is picked up, using the INT pin.

Safety notes

Conclusion

The MPU6050 is a cheap and well-documented way to add six-axis motion sensing to a project. Wake it from sleep mode, calibrate the offsets, pick the lowest range that fits, and combine the accelerometer and the gyroscope for stable angles. For a compass heading you need a magnetometer, or a chip like the BNO055.

Chip data is from the InvenSense MPU-6000/MPU-6050 product specification and register map. The filter formula and the comparison row are general knowledge.