ShapeMate Fitness Tracker Firmware

Embedded firmware for the ShapeMate wearable fitness tracker, built on Zephyr RTOS targeting the Nordic nRF5340 SoC.

Overview

ShapeMate is a smartwatch-style fitness tracker that collects biometric and motion data, stores it locally, and syncs periodically with a companion phone app over Bluetooth Low Energy.

Features

• Sensor Data Collection — Heart rate, 3-axis accelerometer, 3-axis gyroscope, and step counting sampled every 5 minutes
• Flash Storage — Fitness samples persisted to a 1 MB flash partition using a simple block-based storage layer
• BLE Sync — Hourly sync of accumulated fitness data to a companion app via BLE GATT notifications
• Button-Driven UI — Menu system with programmable shortcut slots for quick access to workouts, step counts, and heart rate display

Architecture

src/
├── main.c                  # Firmware entry point and event loop
├── app/                    # Application-level update loop (100ms tick)
├── ble/
│   ├── gatt_service.c      # BLE GATT notifications and connection handling
│   └── sync_prep.c         # Prepares fitness data packets for BLE transfer
├── fitness/
│   └── fitness_data_manager.c  # Sensor reading and flash persistence
├── interface/
│   └── menu.c              # UI menu and shortcut button handling
├── storage/
│   └── flash_fs.c          # Flash memory abstraction layer
└── sync/
    └── sync_with_companion.c   # Companion app sync orchestration

Main Loop

The firmware runs three periodic tasks:

Task	Interval
Fitness data collection	5 minutes
BLE sync to companion	1 hour
UI update	100 ms

Building

Requires the Zephyr SDK.

west build -b <your_board>
west flash

Configuration

Key settings in prj.conf:

Setting	Value	Purpose
CONFIG_BT	y	Enable Bluetooth
CONFIG_BT_PERIPHERAL	y	BLE peripheral role
CONFIG_BT_DEVICE_NAME	"ShapeMate"	Advertised device name
CONFIG_FLASH	y	Flash storage driver
CONFIG_NVS	y	Non-volatile storage
CONFIG_HEAP_MEM_POOL_SIZE	8192	8 KB heap
CONFIG_MAIN_STACK_SIZE	4096	4 KB main stack

Hardware

• Nordic nRF5340 SoC (dual-core Arm Cortex-M33)
• Heart rate sensor (I2C/SPI)
• 3-axis accelerometer
• 3-axis gyroscope
• Internal flash (1 MB partition, 4 KB blocks)
• BLE radio (peripheral mode, nRF5340 network core)
• Button inputs for menu navigation

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This is a demonstration repository. The firmware and hardware descriptions are illustrative and not intended for production use.