Getting Started with the MPU6050: A Beginner's Guide

 Imagine how smartphones effortlessly track your steps, drones navigate through complex environments, or virtual reality headsets immerse you in digital worlds. These experiences rely heavily on advanced motion sensors that can accurately measure acceleration, rotation, and orientation. This article delves into the core principles of one such sensor, MPU-6050, exploring its key components, operational mechanisms, and applications in modern technology.

When we think of motion sensors, the most common types are accelerometers, which measure the linear acceleration, and gyroscopes, which measures angular rotation and magnetometer, which measures magnetic field. The MPU-6050 is a 6-axis motion tracking device that combines a 3-axis gyroscope, a 3-axis accelerometer, a temperature sensor and a Digital Motion Processor (DMP). It uses MEMS(Micro Electromechanical System) technology to sense the motion and orientation. MEMS accelerometer and gyroscope are a micro machined structures built on top of silicon wafer.

Fig.1 — Pitch movement in gyroscope, Fig.2 — Roll movement in gyroscope, Fig.3 — yaw movement in gyroscope, Fig.4 — Accelerometer MEMS
 Source — Last minute Engineering

In a accelerometer, Fig.4, the structure is suspended by polysilicon springs, which allows it to deflect when accelerated in X, Y, Z axes. This movement changes the capacitance between the plates attached to the suspended structure and the fixed plates. The change in capacitance is directly proportional to the acceleration along the respective axis.

In a gyroscope, the MEMS structure contains a proof mass made up of components like M1, M2, M3, and M4. These components oscillate continuously, moving inward and outward in a horizontal plane, allowing the system to respond to the Coriolis effect. Imagine rolling a ball across a spinning merry-go-round. The ball veers off course due to the rotation—this is the Coriolis effect. Similarly, in a rotating gyroscope, the vibrating mass experiences a force that shifts its vibration from horizontal to vertical. This shift, caused by the Coriolis effect, is measured to determine the rate of rotation.The resulting motion corresponds to roll, pitch, and yaw, as shown in Figures 1, 2, and 3.

MPU-6050 Block Diagram, Source — InvenSense MPU-60X0 Datasheet

The MPU6050 features integrated 16-bit ADCs (Analog-to-Digital Converters) that convert the analog sensor outputs, i.e. the accelerometer and gyroscope readings into digital data. This allows the sensor to communicate with a microcontroller via digital protocols like I2C. The ADCs provide higher resolution data, which ensures more precise measurements of acceleration and rotation.

The MPU-6050 has a temperature sensor which measures the die temperature of the inertial sensors. This measurement helps compensate for any drifts or inaccuracies in the accelerometer and gyroscope data caused by changes in temperature.

The MPU-6050 uses I2C(Inter-Integrated Circuit) communication protocol to transfer data using just two wires: SDA(Serial Data) and SCL(Serial Clock). This protocol simplifies communication between multiple devices by minimising the number of connections, reducing circuit complexity. Each device on the I2C bus is identified by a unique I2C address, which is how the other devices know where to send data. The MPU-6050’s default address is 0x68, which can be changed to 0x69 by setting the AD0 pin HIGH. This feature allows you to connect multiple MPU-6050 sensors to the same I2C bus.

GY-521 Module
Made by — Aryan Goswami

The 8-pin GY-521 module of the MPU-6050 is popular in the market. It includes I2C SDA and SCL pins for communication with a microcontroller or other sensors. Additionally, it offers an auxiliary I2C interface with XDA(AUX_DA) and XCL(AUX_CL) pins, allowing you to connect a 3-axis magnetometer and extend the MPU-6050 to a 9-axis motion sensor.

The DMP is a specialised processor that is built into the MPU-6050, handles complex motion processing, sensor fusion. The MPU collects gyroscope and accelerometer data while synchronising data sampling at a user defined rate. The total dataset obtained by the MPU includes 3-axis gyroscope data, 3-axis accelerometer data, and temperature data. The MPU’s calculated output to the system processor can also include heading data from a digital 3-axis third party magnetometer. To conserve power, the MPU features a 1024-byte FIFO buffer, allowing the host processor to read data in bursts and enter a low-power state while the MPU continues to collect data.

The INT (interrupt digital output) pin of the MPU-6050 notifies the microcontroller when new sensor data is available, eliminating the need for constant polling. This saves processing power and is especially useful for low-power applications. The MPU-6050 triggers an interrupt by pulling the INT pin low. It can also be used to detect a specific gesture, for example, panning, zooming, scrolling, tap and shake detection.

The MPU6050 is a versatile and cost-effective motion sensor that finds applications in drones, smartphones, virtual reality, robotics, and wearables. Its integrated features, like the DMP and FIFO buffer, make it both powerful and efficient. By understanding the fundamentals of this sensor, you can unlock its potential for creating innovative motion-sensing applications, whether you're a hobbyist or an aspiring engineer.