A real-time Battery Management System implemented on the STM32F407 Discovery board using FreeRTOS. This system continuously samples voltage, current, and temperature; computes state of charge (SoC) and state of health (SoH); detects faults; updates an OLED display; and transmits data over UART in JSON format.
- Dual ADC sampling using DMA (voltage & current)
- Periodic temperature monitoring
- State of Charge (SoC) and State of Health (SoH) computation
- OLED display output for live system stats
- Fault detection and buzzer alerts
- UART output (JSON format) for Wi-Fi module
- Wi-Fi integration via ESP8266
- Firebase Realtime Database push
- Android app for real-time monitoring
- Multi-tasking using FreeRTOS
The Battery Monitoring System is designed using a layered abstraction architecture, dividing the system into three key levels: Hardware Layer, Firmware Layer, and Software Layer. This modular structure ensures high cohesion within layers and low coupling between them, making the system robust, scalable, and easy to debug.
This layer includes all physical components that sense electrical signals, display system status, and control charging behavior. It forms the foundation of the entire Battery Management System (BMS).
-Measures charging current via Hall effect
-Sends analog output to STM32 ADC for sampling
-Steps down battery voltage to safe levels (<3.3V)
-Enables direct connection to STM32 ADC
-Detects battery surface temperature
-Outputs analog voltage proportional to temperature
-Shows real-time stats: voltage, current, SoC, SoH, temperature
-Triggers manual data upload or reset
-Connected to GPIO with internal pull-up
-Emits alert sounds on over-temperature or fault conditions
-Charges 18650 battery via USB Type-C
-Battery is the only component connected to this charger
-Provides main power storage
-Connected through current sensor and voltage divider
-Communicates with STM32 via UART
-Pushes data to Firebase Realtime Database
-Enables real-time mobile monitoring via custom Android app
-TP4050 module charges only the 18650 battery
-Charging current is monitored via ACS712
-STM32, sensors, display, buzzer, and Wi-Fi module powered by STM32 onboard LDO regulator
-LDO is fed from the DC rail or battery, ensuring system remains operational when charging or running standalone
-Initially planned for persistent data logging (e.g. charge cycles, runtime)
Removed due to I2C bus congestion and hardware layout constraints
This layer runs on the STM32F407 microcontroller and is responsible for data acquisition, control logic, and real-time task management. It orchestrates all sensor readings, computations, and communications using FreeRTOS.
-Simultaneously samples battery voltage and charging current using two ADC channels with DMA.
-Ensures efficient, non-blocking data collection.
-Reads NTC thermistor every 10 seconds.
-Used for thermal safety control and display updates.
-Calculates State of Charge (%) and estimates State of Health (%) based on usage history.
-Logic executed in a dedicated processing task.
-Displays live system stats like voltage, current, temperature, SoC, SoH, and fault flags.
-Display refreshes are throttled to avoid I2C bus congestion.
-Continuously checks for abnormal conditions (e.g., over-temp, short circuit).
-Triggers buzzer and safety logic when necessary.
-Periodically sends system status to ESP8266 via UART in JSON format.
-Enables seamless cloud integration.
Tasks separated by functionality:
-SamplingTask for ADC + temperature
-ProcessTask for SoC/SoH computation
-DisplayTask for OLED
-UploadTask for UART output
-BuzzerTask for audible alerts
Shared data protected using xSemaphore
The ESP8266 NodeMCU acts as the Wi-Fi bridge between the STM32 microcontroller and the Firebase Realtime Database.
-Listens to JSON-formatted data from STM32 over Serial.
-Parses the received JSON and uploads it to a specified node in Firebase Realtime Database.
-Automatically connects to the specified Wi-Fi SSID and password on startup. -Includes basic reconnection logic to maintain uptime.
-Only pushes data when new data is received or when a manual upload is triggered (optional future feature).
-ESP8266WiFi.h for Wi-Fi communication
-FirebaseESP8266.h for Realtime Database integration
-ArduinoJson.h for decoding STM32 JSON messages
The Android app provides a real-time, user-friendly interface for monitoring the battery system remotely via Firebase.
-Automatically fetches the latest battery data from Firebase and updates the UI every second.
-Clearly displays:
-Battery name & status
-Voltage, current, temperature
-Charging time and cycles
-Fault and charge-up flags
-Implements OnDataReceivedListener interface to handle Firebase fetch success/failure callbacks with proper UI messaging.
-Firebase Realtime Database for cloud backend
-ViewBinding for efficient and type-safe UI updates
-Handler + Runnable for periodic polling
-Android Studio + Kotlin as development stack
-MainActivity.kt handles lifecycle & UI updates
-FirebaseManager.kt abstracts Firebase data access
-Uses a listener pattern to decouple networking from UI logic
Firmware/: Contains your STM32CubeIDE project with FreeRTOS integration and all STM32-specific code.
ESP8266_Firmware/: Arduino sketch for the NodeMCU to receive UART data and push it to Firebase.
AndroidApp/: Android Studio project that listens to Firebase and updates UI.
Docs/: Place architecture diagrams, flowcharts, and any helpful visuals here.
README.md: This file β the central documentation hub for your project.