MPU6050 with Arduino Nano — pitch and roll over I2C

The MPU6050 is the motion sensor in self-balancing robots, gesture controllers and tilt alarms. On the Nano it is an I2C device on A4 (SDA) and A5 (SCL), powered from 5V through the GY-521’s regulator.

The sketch prints pitch and roll worked out from gravity, plus the gyro’s Z-axis rate and the chip’s internal temperature (which reads a few degrees above room temperature — it is the die, not the air).

Wiring

Every connection
Arduino Nano	MPU6050 (GY-521)	Wire	Notes
5V	VCC	red	GY-521 has its own 3.3 V regulator.
GND	GND	black
A5	SCL	yellow
A4	SDA	blue

3.3–5 V (on-board 3.3 V regulator) part, 5 V board. The GY-521 has a 3.3 V regulator and pulls SDA/SCL up to 3.3 V, so it works on both 3.3 V boards and a 5 V Uno without a level shifter.

Board quirks

Leave AD0 unconnected (or to GND) for address 0x68. Tie it to 5V for 0x69 when you need two sensors.
XDA/XCL are for an external magnetometer — leave them unconnected.
The GY-521 pulls SDA/SCL up to 3.3 V. The Nano reads that fine; the AVR Wire library also turns on weak internal pull-ups to 5 V, which the module tolerates in practice.
Pitch and roll from the accelerometer alone wobble when the board moves. For a balancing robot, add a complementary filter with the gyro.

Code

mpu6050-nano.inoArduino C++Open in Playground Flash

// MPU6050 (GY-521) accelerometer + gyro on an Arduino Nano, with tilt angles in degrees.
// VCC → 5V (the module has a 3.3 V regulator), GND → GND, SCL → A5, SDA → A4. AD0 open = 0x68.
#include <Wire.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>

Adafruit_MPU6050 mpu;

void setup() {
  Serial.begin(115200);
  if (!mpu.begin()) {
    Serial.println(F("MPU6050 not found - check A4/A5 wiring and address 0x68"));
    for (;;) {}
  }
  mpu.setAccelerometerRange(MPU6050_RANGE_4_G);
  mpu.setGyroRange(MPU6050_RANGE_500_DEG);
  mpu.setFilterBandwidth(MPU6050_BAND_21_HZ);
  Serial.println(F("MPU6050 ready"));
}

void loop() {
  sensors_event_t a, g, temp;
  mpu.getEvent(&a, &g, &temp);
  float ax = a.acceleration.x, ay = a.acceleration.y, az = a.acceleration.z;
  float pitch = atan2(ax, sqrt(ay * ay + az * az)) * 57.2958;
  float roll = atan2(ay, az) * 57.2958;
  Serial.print(F("Pitch: "));
  Serial.print(pitch, 1);
  Serial.print(F("  Roll: "));
  Serial.print(roll, 1);
  Serial.print(F("  Gyro Z: "));
  Serial.print(g.gyro.z, 2);
  Serial.print(F(" rad/s  Chip temp: "));
  Serial.print(temp.temperature, 1);
  Serial.println(F(" C"));
  delay(250);
}

// MPU6050 (GY-521) accelerometer + gyro on an Arduino Nano, with tilt angles in degrees.
// VCC → 5V (the module has a 3.3 V regulator), GND → GND, SCL → A5, SDA → A4. AD0 open = 0x68.
#include <Wire.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>

Adafruit_MPU6050 mpu;

void setup() {
  Serial.begin(115200);
  if (!mpu.begin()) {
    Serial.println(F("MPU6050 not found - check A4/A5 wiring and address 0x68"));
    for (;;) {}
  }
  mpu.setAccelerometerRange(MPU6050_RANGE_4_G);
  mpu.setGyroRange(MPU6050_RANGE_500_DEG);
  mpu.setFilterBandwidth(MPU6050_BAND_21_HZ);
  Serial.println(F("MPU6050 ready"));
}

void loop() {
  sensors_event_t a, g, temp;
  mpu.getEvent(&a, &g, &temp);
  float ax = a.acceleration.x, ay = a.acceleration.y, az = a.acceleration.z;
  float pitch = atan2(ax, sqrt(ay * ay + az * az)) * 57.2958;
  float roll = atan2(ay, az) * 57.2958;
  Serial.print(F("Pitch: "));
  Serial.print(pitch, 1);
  Serial.print(F("  Roll: "));
  Serial.print(roll, 1);
  Serial.print(F("  Gyro Z: "));
  Serial.print(g.gyro.z, 2);
  Serial.print(F(" rad/s  Chip temp: "));
  Serial.print(temp.temperature, 1);
  Serial.println(F(" C"));
  delay(250);
}

Library: Adafruit MPU6050 (Adafruit (also install Adafruit Unified Sensor and Adafruit BusIO)) — compiled with Adafruit MPU6050 2.2.9.

Expected serial output

Serial Monitor · 115200Output

MPU6050 ready
Pitch: 1.8  Roll: -0.6  Gyro Z: 0.01 rad/s  Chip temp: 31.2 C
Pitch: 24.5  Roll: -3.1  Gyro Z: -0.42 rad/s  Chip temp: 31.2 C

MPU6050 ready
Pitch: 1.8  Roll: -0.6  Gyro Z: 0.01 rad/s  Chip temp: 31.2 C
Pitch: 24.5  Roll: -3.1  Gyro Z: -0.42 rad/s  Chip temp: 31.2 C

Common errors

MPU6050 not found

SDA/SCL swapped, AD0 floating at the wrong level, or a fake chip with a different WHO_AM_I. Full fix.

Sketch uses too much memory

The Adafruit stack uses about 14 KB of flash on a Nano — fine alone, but tight with an OLED too. Drop serial strings or switch to a lighter library.