PulseFit is a compact, energy-efficient, and wearable ECG monitoring device designed for sports and fitness enthusiasts. The project integrates cutting-edge hardware, efficient circuit design, and robust BLE communication to deliver real-time heart rate monitoring in an easy-to-use format. The device is ideal for users looking to track their cardiovascular health during physical activity.

1. Project Overview
2. Key Features
3. System Overview
4. Hardware Components
   • ECG Sensor
   • Microcontroller
   • Power Management
   • Peripherals
5. PCB Design
6. Power Consumption Analysis
7. Bill of Materials (BOM) and Cost
8. Usage Instructions
9. Development and Design History
10. Contributors

PulseFit is a wearable chest strap designed to monitor ECG signals and transmit data wirelessly to a connected device. The device leverages an AD8232 ECG sensor for accurate biopotential signal acquisition and a CC2640 microcontroller for data processing and BLE communication. With a battery life of over 40 hours, PulseFit balances functionality, portability, and cost, making it ideal for fitness tracking.

• Advanced ECG Monitoring: High-gain AD8232 sensor tailored for real-time heart rate analysis.
• BLE Communication: Integrates BLE 5.0 for seamless data transmission to smartphones or fitness devices.
• Compact and Lightweight: PCB dimensions of 5.1 x 2.39 cm, designed for user comfort.
• Rechargeable and Sustainable: LiPo battery with USB charging, providing up to 40 hours of use on a single charge.
• User Feedback: RGB and charge status LEDs for clear device status indication.
• Robust Design: Operates efficiently in extreme environments (-40°C to +85°C).

The PulseFit system includes the following subsystems:

1. Signal Acquisition:
   • Captures ECG signals using the AD8232 sensor.
   • Optimized for minimal interference and high signal integrity.
2. Data Processing:
   • Processes signals with the CC2640 ARM Cortex-M3 microcontroller.
   • Converts analog signals to digital values for BLE transmission.
3. Power Management:
   • Voltage regulator (MAX1759EUB) adapts battery voltage to 3.3V.
   • LiPo battery with USB recharging and thermal protection.
4. User Interaction:
   • RGB LED for operational feedback and Red/Green LEDs for charge status.
5. Wireless Communication:
   • A 2.4 GHz BLE antenna ensures efficient and reliable data transmission.

• Model: AD8232
• Purpose: Captures biopotential signals with minimal interference.
• Configuration: "Next-to-Heart" mode for enhanced cardiac signal strength.
• Specifications:
  • Low supply current: 170µA
  • Shutdown mode: 40nA
  • Integrated right-leg drive amplifier
  • High CMRR: 80 dB
• Advantages: Compact design with minimal external components for noise reduction.

• Model: CC2640 (Texas Instruments)
• Core: ARM Cortex-M3 @ 48 MHz.
• Features:
  • Integrated BLE 5.0 controller.
  • Ultra-low power standby mode (1.5µA).
  • Analog-to-Digital Converter (ADC) for ECG signal processing.
• I/O:
  • Dedicated GPIO for RGB LEDs and ECG sensor control.
  • JTAG interface for debugging.

• Battery: LP402025 LiPo (150mAh).
• Charger: MCP73831 USB charger with constant-current/voltage control.
• Voltage Regulator: MAX1759EUB for stable 3.3V output.
• LED Indicators:
  • Red: Charging.
  • Green: Fully charged.

• Electrodes: Gold-plated, dry electrodes for superior signal quality and durability.
• Antenna: 2.4 GHz patch antenna for BLE communication.
• Buttons: Reset button and power slide switch.

• Dimensions: 5.1 x 2.39 cm.
• Component Placement:
  • Antenna positioned for minimal interference.
  • ECG sensor placed close to the microcontroller for short signal paths.
  • Power components grouped together for efficient routing.
• Routing:
  • Trace width: 0.25 mm to minimize impedance.
  • Class 5C compliance for manufacturing standards.
• Ground Plane:
  • Provides noise shielding for critical components.

Average power consumption:

• Microcontroller: 3.02mA.
• ECG Sensor: 0.17mA.
• RGB LEDs: 0.51mA.
• Estimated Battery Life: ~40 hours (150mAh battery).

1. Setup:
   • Charge the device via USB.
   • Attach the chest strap securely with electrodes in place.
2. Operation:
   • Power on using the slide switch.
   • Observe RGB LED indicators for device status.
   • Pair with a BLE-compatible device to monitor ECG data.
3. Maintenance:
   • Clean electrodes after use.
   • Recharge battery as needed.

In this project, the main files are the following:

• A project directory with 2 subfolders :

  • "Temp" directory contains the entire project, both the Capture project and the Allegro board

  • "ORCAD_PERSONAL_LIBRARY" contains every .OLB for the schematic libraries, every footprint contained in the board and relative .psm in the subfolder "FOOTPRINTS" and every padstack (.pad) in the "PADSTACK" folder.

• The REPORT of the project (.pdf)

• The BOM containing every cost related to the device, with every price based on the purchase quantity (.xslx)

• The video demo of the project (.mp4)

• Slides of the video demo (.pdf)

• v1.1: Initial schematic and PCB design.
• v1.2: Introduced slide switch for improved usability.
• v1.3: Optimized electrode connectivity.
• v1.4: Improved component spacing and reduced manufacturing costs.
• v1.5: Added mounting holes for secure casing attachment.

• Alessandro Marchei
• Silvia Capozzoli

For full documentation and design files, please refer to the docs folder, which contains the 'pulsefit.pdf' for the entire report documenting the purpose and details of the entire project.