Gyroscope We have looked at how to interface the BH1750 ambient light sensor and the MAX30102 Heart rate sensor for our smartwatch project in the previous part, which was titled Designing Smartwatch Using ESP32. This part was split into two parts. In this section, we will discuss the different types of sensors that can be interfaced with our smartwatch and how to do so. The HMC5883L/QMC5883L Magnetometer sensor and the MPU6050 accelerometer gyroscope sensor are going to be interfaced in this section. We are going to examine the process of interfacing each of these modules independently. Prerequisites - Installing Necessary Libraries The GitHub repository that is linked to at the bottom of the article contains all of the necessary library files. You will need to download them and then extract them into the library folder that is located inside of the Arduino

document folder. You can skip the step before this one if you have already installed the necessary components, but you will still need to install the display library. You are required to use the TFT eSPI library that I have attached for the display. When that is finished, let's move on to the next step, which is the interface. Required Libraries 1. TFT_eSPI Library (Modified) 2. QMC5883L Library from DFRobots Interfacing Magnetic Sensor The HMC5883L/QMC5883L is going to be the component that we use for the magnetic sensor. We can make use of the sensor as a digital compass given that it is able to indicate the geographic directions of north, south, east, and west. Inside of the HMC5883L/QMC5883L are three different magneto-resistive materials that are organized along the axes of x, y, and z. The strength of the earth's magnetic field has an effect on the amount of electric current that flows through these materials. Therefore, we are able to detect shifts in the magnetic field of the Earth by monitoring the change in the current that is flowing through these materials. After the change in the magnetic field has been absorbed, the values can then be sent to any embedded controller using the I2C protocol. Examples of embedded controllers include a microcontroller and a processor. HMC5883L/QMC5883L Module Pinout

A total of five pins are present on the HMC5883L/QMC5883L module. With the exception of the VCC and Ground pins, all of the pins on this sensor module are digital. There is one optional interrupt pin in addition to the four pins that are used for interfacing with the MCU. The HMC5883L/QMC5883L module has the following pinout, as specified by

GND - Ground connection for the module. Establish a connection to the ESP32's GND pin. VCC - Provides power for the module. Establish a connection to the ESP32's 3.3V pin. SCL - stands for Serial Clock. Utilized for the purpose of providing the clock pulse for I2C Communication. SDA - Serial Data pin. Used for moving data between devices using the I2C communication protocol. DRDY - An interrupt is generated in this pin whenever the output value of the sensor is ready to be read. By default, the module has a pull-up resistor connected to this pin. The value of the output pin is set to "0" for a period of 250 microseconds when the module's output value is ready. Circuit to Interface a Magnetic sensor with an ESP32

When conducting tests, ensure that the Magnetic sensor module and the display module are connected to the ESP32 Devkit in accordance with the circuit diagram that can be found below. As you did in the previous step, connect the display to the SPI bus and the sensor to the I2C line. The actual configuration can be seen here. I2C lines are used to make the connection between the ESP32 and the QMC5883L module. Testing Sensor The QMC5883L demo code and any necessary libraries can be obtained from GitHub once all of the connections have been completed in accordance with the schematics. The libraries should be extracted into the Arduino library folder, while the code should be extracted into any folder, and then opened in the Arduino IDE. Compile the code after selecting "ESP32 Devkit" as the board to use. After the code has been compiled, it can then be uploaded to the ESP32.

On the display will be a digital representation of a compass. You can see that the compass is pointing in the right direction, and it will continue to do so so long as there is no magnetic interference. You can verify this by looking at it. Make sure there aren't any magnetic materials or magnetic fields in the area around the sensor while you're testing it. In that case, it might have an effect on the readings. Code explanation Both the TFT eSPI and DFRobot QMC5883 libraries were incorporated into the code by our team. The HMC5883L and QMC5883L chip families

are both supported by the DFRobot QMC5883 library. After we have finished initializing the library, we will set the appropriate configuration based on the chip address that we have been given. This is necessary due to the fact that both of these sensors have distinctive I2C addresses and distinct internal register mappings. When it is finished, we will read the register that corresponds to the reading from each axis, and then we will compute the heading based on that information. Adjusting the declination angle to account for our location is necessary in order to carry out an accurate calculation. You can look in the code itself to find the instructions for doing the same thing. After the bearing has been determined, the image of the compass dial will be loaded into the sprite that was previously created in the memory. The sprite is then angledly pushed onto the display after it has been rotated. In order to accomplish this, we have made use of the pushRotated function that is located within the TFT eSPI library. Because of this function, the image that is being sent to the display will be rotated so that it corresponds with the angle that was determined using the QMC5883L. By doing this, our display will be clear and we will have an accurate digital compass that is pointing to the north. In order to achieve precise results, it is essential to secure the sensor in the appropriate orientation and keep it away from any magnetic substances. It is important to keep in mind that even the breadboard's contacts can have an effect on the sensor. Interfacing Accelerometer Gyroscope sensor We went with the reliable and widely used MPU6050 sensor for the accelerometer and gyroscope sensor. The fact that it is both inexpensive and simple to work with contributes to the DIY community's widespread adoption of the product. This sensor will be utilized by us for the purpose of

detecting motion and enabling features such as rise to wake up. First, let's take a look at the sensor's individual technical specifications. The MPU6050 is a widely used accelerometer and gyroscope chip that has a measurement resolution of 16 bits and features six axes of sensing capability. Due to the low price and the high accuracy in sense, it has gained a lot of popularity in the do-it-yourself community. Even a large number of commercial products have the MPU6050 embedded in them. Inertial measurement units, also known simply as IMUs, are typically comprised of gyroscopes and accelerometers. IMU sensors are utilized in a huge selection of applications, including mobile phones, tablets, satellites, spacecraft, drones, unmanned aerial vehicles (UAVs), robotics, and many others. Motion tracking, detection of orientation and position, flight control, and other applications all make use of them. MPU6050 Module Pinout A total of 8 pins can be found on the MPU6050 module. where the interfacing requires a minimum of four pins in order to function properly. The following is a list of the pinouts on the MPU6050 module:

GND - Module's ground connection. Establish a connection to the ESP32's GND pin. VCC - supplies power to the module. Establish a connection to the ESP32's 3.3V pin. SCL - stands for Serial Clock. Utilized for the purpose of providing the clock pulse for I2C Communication. SDA Serial Data pin. Used for moving data between devices using the I2C communication protocol. XDA - Auxiliary Serial Data - Can be used to connect MPU6050 with other I2C modules. XCL - Auxiliary Serial Clock: This can be used to connect MPU6050 to other I2C modules. ADD/AD0 - Address select pin in the event that more than one MPU6050 module is being utilized. INT - Interrupt pin used to indicate to MCU that data is ready to be read. Circuit Diagram for the ESP32 and Accelerometer/Gyroscope Sensor Connect the accelerometer gyroscope sensor module and the display module to the ESP32 Devkit in accordance with the circuit diagram that can be found below. This will allow you to test the device. As you did in the previous step, connect the display to the SPI bus and the sensor to the I2C line.

The actual configuration can be seen here. In order to have the freedom to move the module around while the test is being performed, the MPU6050 module is connected using a jumper cable. Testing Sensor When you have finished making all of the connections in accordance with the schematics, go to GitHub and download the MPU6050 demo code. It should then be opened in the Arduino IDE after being extracted to a folder. Compile the code after selecting "ESP32 Devkit" as the board to use. After the code has been compiled, it can then be uploaded to the ESP32. The display will depict a cube in three dimensions. The cube can be rotated by rotating the MPU6050 module in its center. The gyroscope data will be read from the MPU6050 by the ESP32, and the 3D cube will be processed according to those values. Code Explanations Within the code, we have produced a three-dimensional cube that is comprised of a total of twelve lines. The reading from the gyroscope sensor

will determine the direction that the cube will rotate in. The cube can be rotated by rotating the MPU6050 module in its center. The gyroscope data will be read from the MPU6050 by the ESP32, and then the data will be processed in order to calculate the coordinates of each line that is used to create the 3D. We have not made use of any particular library in order to read the values that are stored in the MPU6050. Instead, we read those values directly from the MPU6050 registers using the I2C Wire. Read function. These values were retrieved from the MPU6050. We are going to read a total of 14 registers, each of which will contain the x, y, and z data that was generated by the accelerometer and gyroscope.