Smart Weather Monitor System (SWMS) – Monochrome LCD + LM35

This version of SWMS runs on STM32F401RBT6 (RaayanMini) with a 16x2 monochrome character LCD and an LM35 analog temperature sensor.

It reads temperature from the LM35 via ADC, shows time, date and temperature on a 16x2 HD44780-compatible LCD, and periodically pushes the current temperature to a remote server using an ESP8266 (AT commands over UART).
An external I²C RTC keeps track of date/time, and there is basic offline logging to an I²C EEPROM/FRAM when WiFi is down. All the logic is split into FreeRTOS tasks, so different functionalities run in parallel instead of one big blocking loop.

This is a prototyping firmware developed by Kernel Masters students – the goal is to explore ADC, I²C, UART, RTOS basics and simple IoT-style communication on STM32F4, not to build a production-grade weather station.

🛠 Hardware & Tools

• MCU Board: STM32F401RBT6 (RaayanMini, LQFP64)

• Temperature Sensor: LM35 (analog, 10 mV/°C) → connected to ADC1

• Display: 16x2 monochrome character LCD (HD44780-compatible) in 4-bit mode

• RTC: DS1307/DS3231 module over I²C1 (0x68)

• Non-Volatile Log (optional): I²C EEPROM (0x50) for basic offline logging

• WiFi Module: ESP8266 in AT-command mode on UART

• Status LEDs: RED/GREEN on GPIOs for WiFi status indication

• RTOS: CMSIS-RTOS (FreeRTOS backend)

• IDE / Toolchain: STM32CubeIDE v1.18.0

• Project config: .ioc file (CubeMX configuration) included in the repo

Exact pin mapping is configured inside the .ioc file and generated code; that is the single source of truth for pins and peripherals.

🔧 What the Firmware Does (High Level)

1. Power-On & Init

   • Initializes HAL, clocks and peripherals from the CubeMX config.

   • Brings up the 16x2 LCD, shows a simple splash screen.

   • Checks for RTC presence on I²C (0x68). If not found, it reports the error on LCD and stops.

   • Initializes the ESP8266 with a sequence of AT commands (echo off, station mode, join AP, etc.).

   • If WiFi init fails (module not found / wrong SSID/password), it prints a message on LCD and waits.

2. Runtime Behaviour (After RTOS Starts)

   • Task 1 – Display (dispDT)
     Reads time/date from RTC over I²C and updates the LCD with HH:MM:SS and DD/MM/YY.
     When a fresh temperature value is available, it also updates the T:xx°C field on the LCD.

   • Task 2 – Temperature (readTemp)
     Samples the LM35 via ADC at a fixed interval, converts ADC counts to a temperature value, and signals other tasks using a binary semaphore.

   • Task 3 – WiFi Status & Logging (checkIntStatus)
     Periodically checks AT+CIPSTATUS.

     • If WiFi is OK, it lets the upload task run.

     • If WiFi is down, it logs a simple record (timestamp + temp) to an I²C EEPROM.

   • Task 4 – Upload (upTemp)
     When WiFi is OK and a new temperature is ready, it opens a TCP connection and sends a simple HTTP GET with the latest temperature using the ESP8266.

3. Status Indication

   • A pair of LEDs (RED / GREEN) show WiFi link status (disconnected / OK).

   • The LCD always shows current time, date, and temperature, so the system is still useful even if WiFi is not working.

🧵 RTOS Task Layout

Task Name	What It Does	Notes
dispDT	Reads RTC, updates LCD (time/date/temp)	Uses I²C RTC + LCD driver
readTemp	Samples LM35 via ADC and computes °C	Runs periodically, sets “new temp” flag
checkIntStatus	Checks WiFi status + decides upload/log path	Uses AT+CIPSTATUS, toggles LEDs
upTemp	Sends HTTP GET with temperature over ESP8266	Runs only when WiFi OK + new temp present

Binary semaphores are used for synchronization between sensor, status, and upload tasks.

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🚀 Getting Started

1. Clone the Repository

Download the repository as .zip
Extract the .zip file

2. Import into STM32CubeIDE

1. Open STM32CubeIDE v1.18.0

2. Go to File → Open Projects from File System…

3. Point it to the project root and import.

4. You should see the project with its .ioc file.

2.5. Regenerate HAL Drivers / Middleware (Important)

The repo’s .gitignore usually excludes auto-generated HAL, CMSIS and Middleware sources.
If Drivers/ and Middlewares/ are missing or incomplete:

1. Open the .ioc file in STM32CubeIDE.

2. Click Project → Generate Code (or the “gear” icon in the CubeMX toolbar).

3. Confirm that:

   • Core/ (user code) is present

   • Drivers/ and Middlewares/ are now generated

Without this step, the project will not build.

3. Configure WiFi Credentials & Server

Open the WiFi/ESP8266 source file (for example wifi.c) and update:

#define WIFI_SSID "your-ssid"
#define WIFI_PASSWORD "your-password"

If you want to send data to your own server instead of the hard-coded one, adjust the IP/URL and HTTP GET string inside the upload function (around AT+CIPSTART and the formatted "GET /... string).

4. Wire the Hardware

• Follow the pin mapping defined in the .ioc file.

• Ensure:

  • LM35 output goes to the configured ADC pin (e.g. ADC1_INx).

  • LCD data and control lines match the GPIOs in the LCD driver.

  • RTC and EEPROM/FRAM are on the configured I²C bus.

  • ESP8266 TX/RX are on the correct UART pins.

  • All modules share GND and run at 3.3 V where required.

5. Build & Flash

1. Connect the RaayanMini (STM32F401) board via ST-Link.

2. In STM32CubeIDE:

   • Click Build to compile.

   • Click Run or Debug to flash the firmware.

On reset, you should see:

• LCD splash → RTC check → WiFi init messages.

• Once WiFi connects successfully, LCD will switch to live time/date/temperature view.

• RED/GREEN LEDs will start reflecting WiFi status.

• Temperature readings will be periodically uploaded via HTTP GET.

• If WiFi fails, basic logs are written to I²C EEPROM/FRAM instead.

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⚙️ What This Project Teaches / Demonstrates

• Using FreeRTOS (CMSIS-RTOS) to split functionality into multiple coordinated tasks.

• Interfacing with LM35 (ADC), RTC + EEPROM (I²C), and ESP8266 (UART AT) in one design.

• Doing BCD conversions and time/date formatting from an external RTC.

• Implementing small but real state checks like WiFi link status and a fallback logging path.

• Building a simple but clean 16x2 LCD UI for embedded systems instead of relying only on UART printf.