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Programs

The main objective is to read data from an IMU sensor and send this data to a main computer for its real-time processing.

Program to read data from an IMU sensor

A first simple program is created to read IMU MPU9250 sensor. We can use the libraries:

  • SparkFunMPU9250-DMP (IMU_read1.ino)
  • MPU9250 by hideakitai (IMU_read2.ino)

For the second library you have to install it:

  • Press crtl+shift+p
  • type Arduino and select "library manager"
  • type MPU9250 and select the one from hideakitai
  • install

We propose you some sample programs to review the communication performances using:

  • Bluetooth
  • WiFi

1. Bluetooth communication

The ESP32 offers both Classic Bluetooth (BR/EDR) and Bluetooth Low Energy (BLE).

Classic Bluetooth (BR/EDR):

  • Higher Data Rates: Designed for continuous data streaming
  • Higher Power Consumption
  • Range: Generally 10-30m
  • Use Cases: Audio streaming (A2DP), serial communication (SPP), and other applications requiring continuous data transfer.

Bluetooth Low Energy (BLE):

  • Low Power Consumption
  • Lower Data Rates: Not ideal for continuous high-bandwidth data streaming.
  • Short Bursts of Data: Designed for unfrequent data transfers, such as sensor readings, notifications, and control signals.
  • Range: Can achieve comparable or even better range than Classic Bluetooth
  • Use Cases: Wearables, IoT devices, and other applications where low power consumption is crucial.

We will use Classic Bluetooth to send data to:

  • a mobile phone: You need to install one of the following Apps to be able to see the data sent by the ESP32:
    • Serial Bluetooth Terminal App
    • BluetoothElectronics App
    • Arduino Bluetooth control App
    • others...
  • computer: Has to be able to read the data sent by the ESP32, or you need to use a Bluetooth dongle.

BT_test1:

  • Read input from monitor and write to Mobile
  • Read input from Mobile and write to Serial Monitor
Serial Monitor Mobile Phone BT

BT_test2:

  • Send data to Mobile
  • Send data to Serial Monitor
Serial Monitor Mobile Phone BT

BT_IMU_send2phone

We have made some modifications to the initial program to send IMU data to a mobile phone.:
Serial Monitor Mobile Phone BT

BT_IMU_send2PC

We have add to the previous program a python code in out PC to receive IMU data from ESP32 IMU sensor. Before running python code, you need to:

  • Install the libraries: pip install pyserial keyboard
  • Type "Bluetooth" in your PC searching line to Pair your ESP32 with your computer: Through your operating system's Bluetooth settings.
  • Type "Dispositius" to find the Bluetooth port: Look in your operating system's Bluetooth settings or in the "Device Manager" (Windows) to find the port name assigned to your ESP32.
  • Run the Python code.
Serial Monitor PC received BT

2. WiFi communication

Assigning fixed IPs and hostnames to each ESP32 prevents IP conflicts and simplifies device management, making it easier to identify and access each device consistently. This is especially useful in a lab with multiple devices.

A First program has been made to assign IP address and hostname to an ESP32: WiFi_IP_hostname.ino
Serial Monitor

In this program we have created a configureNetwork() function that we can use in applications where we are using several ESP32s.

The main objective is to read an IMU sensor and send data to a local computer to make postprocessing.

The ESP32 offers different interesting options:

  • Webserver
  • Socket UDP

2.1. ESP32 webserver

Publishes IMU data in real-time to a web server located in ESP32

Programs:

  • WiFi_WebServer_IMU1.ino: Uses SparkFun IMU library
  • WiFi_WebServer_IMU2.ino: Uses mpu9250.h IMU library
Serial Monitor Web Server

2.2. Socket UDP

This program reads orientation data (roll, pitch, yaw) from an MPU-9250 sensor connected to an ESP32 and sends this data over a Wi-Fi network using UDP (User Datagram Protocol) to a specified IP address and port.

This is useful for applications where you need to receive sensor data on a computer or other device in real-time. UDP is chosen for its speed and low overhead, making it suitable for streaming data, even though it doesn't guarantee delivery like TCP.

Programs:

  • WiFi_SocketUDP_IMU

    • ESP32 connects to the WiFi network
    • sends IMU data to computer
    • Computer listens to all interfaces (IPs)
    • Extracts the RPY values
Serial Monitor Computer Router

  • WiFi_SocketUDP_2IMU

    ESP32_1 and ESP32_2 sends IMU data to computer

  • WiFi_SocketUDP_Sender_Receiver

    ESP32_receiver listen RPY data from ESP32 sender and ESP32_sender sends RPY data to ESP32_receiver and computer.

    We need to install "ArduinoJson" library:

    • Find the "ArduinoJson by Benoît Blanchon" library in the search results.
    • Click on the "Install" button.

    The description of the program:

    • ESP32_receiver (ESP32_Receiver.ino):
      • connects to the WiFi network
      • displays its IP address on setup
      • receives from ESP32_sender the IMU data
    • ESP32_sender (ESP32_Sender.ino)
      • connects to the same WiFi network
      • sends IMU data to ESP32_receiver and computer
    • Computer (Read_from_sender.py)
      • listens to all interfaces (IPs)
      • Extracts the RPY values received from ESP32_sender
Serial Monitor Receiver (IP: 192.168.0.161) Serial Monitor Sender (IP: 192.168.0.152)
Router Computer received data