Arduino Mega · MPU6050

Arduino Mega MPU6050 Simulator: Wiring, Code and a Live Circuit

This is an MPU6050 accelerometer and gyroscope on a GY-521 board, wired to an Arduino Mega 2560 over I2C and read live: the sketch wakes the chip and prints the three acceleration axes four times a second. In the editor, drag the pitch and roll sliders and watch gravity move between them.

Four wires: 5V, GND, SDA to pin 20 and SCL to pin 21. The sketch talks to the registers with Wire, so nothing is hidden behind a library.

Run it in the editor Read the code

5 V logic
Library: Wire.h only
I2C address 0x68
SDA 20, SCL 21

Arduino Mega · MPU6050live0.000 s 0.00x

Click to open it in the editor

The circuit itself, running on the simulator with the sketch below. Press what can be pressed; click anything else to open it in the editor.

Wiring the MPU6050 to the Arduino Mega

Every connection in the circuit above, with the board’s own pin names.

MPU6050 pin	Arduino Mega pin	Why
VCC	5V	The GY-521 board has a 3.3 V regulator, so it takes 3.3 or 5 V.
GND	GND	Common ground.
SCL	pin 21	I2C clock.
SDA	pin 20	I2C data.
AD0	not connected	Low (the board’s own pull-down): address 0x68. Tie it high for 0x69.

On the Mega the I2C bus is pin 20 (SDA) and pin 21 (SCL), not A4 and A5 as on an Uno. The SDA and SCL pins by AREF are the same two nets. The GY-521’s pull-ups go to its own 3.3 V regulator output, and the ATmega2560 reads 3.3 V as high on I2C, so the module connects directly at 5 V.

Pins to leave alone on the Arduino Mega

Pins 14 to 19 are the three extra serial ports and 20 and 21 are I2C, so keep them free if you will need those. An Uno shield’s I2C on A4 and A5 is not connected to anything on a Mega.

On a real bench

The Mega is long, so put the breadboard beside its double row of pins 22 to 53 and leave the left-hand headers free. The MPU6050 uses only a few of its 54 pins; a Mega earns its size when one sketch drives a keypad, a display and several sensors at once.

The code

The sketch the circuit above runs. Open it in the editor, change a line and press Run: it compiles in your browser.

MPU6050 on Arduino Mega I2C

#include <Wire.h>

const int MPU = 0x68;   // AD0 low

int16_t read16() {
  int16_t high = Wire.read();
  return (high << 8) | Wire.read();
}

void setup() {
  Serial.begin(9600);
  Wire.begin();                 // SDA pin 20, SCL pin 21
  Wire.beginTransmission(MPU);
  Wire.write(0x6B);             // PWR_MGMT_1
  Wire.write(0);                // wake up: it starts asleep
  Wire.endTransmission();
  Serial.println("MPU6050 awake");
}

void loop() {
  Wire.beginTransmission(MPU);
  Wire.write(0x3B);             // ACCEL_XOUT_H, then Y, Z, temperature, gyro
  Wire.endTransmission(false);
  Wire.requestFrom(MPU, 6);
  int16_t ax = read16();
  int16_t ay = read16();
  int16_t az = read16();
  // At the default range, 16384 counts is 1 g.
  Serial.print("Accel x: ");
  Serial.print(ax);
  Serial.print("  y: ");
  Serial.print(ay);
  Serial.print("  z: ");
  Serial.println(az);
  delay(250);
}

The MPU6050 powers up asleep, and every reading is zero until register 0x6B is written with 0. That one write in setup() is the step most broken sketches are missing.

Reading starts at register 0x3B and the chip sends the bytes that follow in order: X, Y and Z acceleration, two bytes each, high byte first. endTransmission(false) keeps the bus between the address write and the read, so the three axes come from the same sample.

Lying flat and still, the board reads 0, 0 and 16384: one g straight down on Z. Tilt it with the pitch and roll sliders and the gravity moves between the axes. This sketch uses Wire directly; Adafruit_MPU6050.h and MPU6050.h also compile here, but the raw registers are what those libraries do underneath. Serial.begin(9600) opens the serial monitor. Serial is the USB port; Serial1 to Serial3 are on pins 18 and 19, 16 and 17, and 14 and 15.

Common mistakes with the MPU6050 on the Arduino Mega

Not waking it up

Out of reset the chip is asleep and returns zeros on every axis. Write 0 to register 0x6B first. It is the single most common MPU6050 fault.

SDA and SCL on A4 and A5

That is the Uno’s bus. On the Mega it is pins 20 and 21, and on A4 and A5 the chip never answers.

Expecting an angle from the gyro

The gyroscope measures how fast the board turns, in degrees per second, not which way it points. For tilt, use the arctangent of two acceleration axes; for a steady angle while moving, combine both with a complementary filter.

Questions and answers

Can I simulate an MPU6050 with an Arduino Mega 2560?

Yes. The circuit at the top of this page is an Arduino Mega 2560 with a MPU6050, running in your browser on a simulated ATmega2560. The pitch and roll sliders tilt the simulated chip, so the acceleration on each axis is what gravity would give at that angle. Press Run it in the editor to change the wiring or the code; it is free and needs no account.

Which pins does the MPU6050 use on the Arduino Mega?

On the Mega the I2C bus is pin 20 (SDA) and pin 21 (SCL), not A4 and A5 as on an Uno. The SDA and SCL pins by AREF are the same two nets.

Why are all my readings zero?

The chip is still asleep: write 0 to register 0x6B. If the readings are -1 instead, nothing answered at 0x68, so check the wiring and the AD0 pin.

Can I use the Adafruit MPU6050 library?

Adafruit_MPU6050.h compiles here. This page reads the registers with Wire so the sketch shows what the chip actually does, and so it runs the same on every board.

Build your own MPU6050 project

Open this circuit in the editor, change the wiring or the code, and keep your version in a free account.

Start building free Open the editor