Smart Socks -- Heart Failure Detector

Week 8 Progress: BLE Android App Development and Testing Objective: To implement and test the BLE (Bluetooth Low Energy) communication feature on the Android mobile application, enabling real-time reception of status, alarm, and ADC data from the ankle-worn hardware device. BLE Communication Principle (Android BLE Overview): BLE is a wireless protocol designed for short-range, low-power communication. It works via a client-server model, where: Peripheral (Server) : The ankle-worn device (XIAO nRF52840), advertises services and characteristics. Central (Client) : The Android phone scans for nearby BLE devices, connects to a chosen peripheral, and subscribes to its characteristics. On Android, the workflow is as follows: Scan for nearby devices using BluetoothLeScanner . Connect to a selected device using connectGatt() . Discover Services to identify the available UUIDs. Enable Notifications for a given characteristic via descriptor 0x2902 . Receive Upd...

Week 7 Progress: BLE Transmission Testing on XIAO nRF52840 Objective: To verify the BLE (Bluetooth Low Energy) functionality of the Seeed Studio XIAO nRF52840 microcontroller and test real-time data transmission from the ankle monitoring system to a mobile app. Hardware Background: The microcontroller used is the Seeed Studio XIAO nRF52840 , a compact and powerful board designed for wireless sensing applications. Key features relevant to this project include: Processor : Nordic nRF52840 (ARM Cortex-M4F, 64 MHz) Memory : 256 KB RAM, 1 MB Flash Connectivity : Integrated BLE 5.0 support Power : Supports 3.3V to 5V input, battery-friendly Size : 21 x 17.5 mm, ultra-compact for wearables Peripheral I/O : 6 analog/digital I/O pins, I2C, UART, SPI support This microcontroller was chosen for its low power consumption, BLE capability, and small footprint—ideal for integrating into the wearable ankle device. Implementation: The board was programmed using the Arduino...

Week 6 Progress: Functional Testing and Hardware Integration Objective: To test all essential functionalities of the newly assembled circuit board, including analog signal acquisition, power stability, and microcontroller operation. Finalize hardware integration by mounting the system onto a flexible wearable base. Implementation: With soldering complete, I carried out basic functional testing on all major subsystems of the board: Power module (battery and Type-C charging) nRF52840 microcontroller Analog inputs from flex sensors Op-amp impedance buffer circuit Microcontroller check: After replacing the previously damaged board in Week 5, the new nRF52840 was connected via USB. A minimal test sketch was uploaded to validate analog input functionality and BLE advertising. Serial output and onboard LED feedback were used to verify the program was running correctly. Analog input test: Connected flex sensors and manually bent them to simulate ankle mov...

Week 5 Progress: Hardware Debugging and Final Soldering Completion Objective: To complete the remaining soldering tasks and verify the full functionality of the ankle monitoring hardware, including power delivery, sensor connectivity, and microcontroller integrity. Implementation: Continued soldering work from Week 4, focusing on finalizing wire connections and mechanical stability of the circuit. After completing initial soldering last week, I attempted to test the nRF52840 microcontroller ; however, it failed to power up and showed no response during USB and BLE testing. Upon closer inspection and multimeter probing, I concluded that the board was likely damaged during prolonged soldering in the previous week. Corrective Actions Taken: Replaced the damaged microcontroller board with a new one of the same model. Redid all soldering connections carefully, using reduced soldering time per pin to avoid overheating. Verified all power, GND, and signal connections be...

Week 4 Progress: Soldering and Initial Hardware Integration Objective: To assemble the hardware system by soldering key electronic components onto a compact custom circuit layout, with the goal of achieving a fully wearable and functional ankle monitoring device. Implementation: Design Decision: To ensure better comfort and wearability, I chose not to use pin headers , opting instead for direct soldering of all components. Component Integration: Based on the approved component list, I soldered the following key modules: Seeed Studio nRF52840 microcontroller (main controller) Flex sensors (x2) Resistors for voltage divider Op-amp module (impedance buffer) 3.7V Lithium battery connector Type-C charging module Wires and connectors for external integration Challenges Faced: Solder pads were very small , especially on the nRF52840 board, making precision soldering difficult. In multiple cases, solder failed to adhere properly to the pad or f...