Project: Connected Watch (Communicating Embedded Systems)

This project, carried out as part of the Master 1 , aimed to design and implement a functional connected watch. Drawing inspiration from the open-source ZSWatch project, the goal was to integrate disparate hardware and software components into a coherent embedded system.

1. Context and Problem

The main challenge was to develop a real-time application on the nrf5340 microcontroller using the Zephyr RTOS. The objective was to create a portable device capable of collecting data (sensors, time), displaying it on a touch-enabled graphical interface, and communicating it via Bluetooth Low Energy (BLE).

2. Project Objectives

• Master Zephyr OS as the real-time software base.
• Integrate and utilize motion and environmental sensors (IMU, temp/humidity) via I2C.
• Manage time persistently using an external RTC module (RV-8263-C8).
• Implement a graphical user interface (GUI) on a TFT touchscreen using the LVGL library.
• Establish BLE communication for data exchange with a smartphone (GATT services).

3. Features Developed

To meet the project requirements, the following features were implemented:

1. Multi-Screen User Interface (GUI)

   • Domain: Graphical display and interaction.
   • Objective: Display the time, sensor data, a pedometer, a compass, and a stopwatch.
   • Tools: Designed with Squareline Studio and rendered by the LVGL library.

2. I2C Sensor Management

   • Domain: Data acquisition.
   • Objective: Read data from sensors (Temperature, Humidity, 6-axis Accelerometer, Magnetometer).
   • Processing: Implemented a simple pedometer and compass.

3. Time Management (RTC) and Stopwatch

   • **Domain:**Timekeeping.
   • Objective: Reliably maintain the time and date (via external RTC RV-8263-C8) and provide a stopwatch function.

4. Bluetooth Low Energy (BLE) Connectivity

   • Domain: Communication.
   • Objective: Send sensor data to a mobile device via standard (ESS for Temp/Humidity) and custom (IMU) GATT services.

4. Technical Environment (Tech Stack)

• Hardware:
  • MCU: Nordic nrf5340
  • Sensors: ST IKS01A3 Shield (LSM6DSO, LIS2MDL, HTS221)
  • Display: Adafruit 2.8” TFT Touch Shield v2
  • RTC: Micro Crystal RV-8263-C8
• Software Ecosystem:
  • OS: Zephyr RTOS
  • SDK: nRF Connect SDK
  • IDE: Visual Studio Code
• Libraries and Tools:
  • Graphics: LVGL (Light and Versatile Graphics Library)
  • UI Design: Squareline Studio
  • BLE Debugging: nRF Connect for Mobile

Links

• GitHub: [https://github.com/M0x3m/Montre_Connectee_Projet]