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README.md

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+# ESP32 Modbus RTU Power Meter
+
+## Overview
+
+This project implements a compact **ESP32 C3 Super Mini-based Modbus RTU power meter interface** designed for monitoring electrical measurements from Modbus-compatible energy meters. The system has been developed and tested using the **Chint DDSU666 Single-Phase Power Meter**, although it is intended to work with any Modbus RTU compliant power meter after appropriate configuration.
+
+The device continuously reads measurement values from the power meter via an RS485 interface and provides multiple methods for visualizing the data:
+
+- Local display using a 128 × 32 OLED screen
+- Integrated Wi-Fi access point with a web interface
+    - Historical data visualization
+    - CSV export of recorded measurements
+
+The compact enclosure is designed to fit inside a **1TE DIN rail distribution box**, making it suitable for electrical installations where space is limited.
+
+<img src="pictures/device_1.jpg" width="600px">
+
+<img src="pictures/device_2.jpg" width="600px">
+
+
+###  Features
+
+- ESP32-C3 Super Mini based implementation
+- Modbus RTU communication over RS485
+- Compatible with the Chint DDSU666 and other Modbus RTU power meters
+- Local real-time display on a 128 × 32 OLED
+- Integrated Wi-Fi Access Point
+- Web interface for monitoring live measurements
+- Historical data visualization
+- CSV export functionality
+- Compact DIN rail enclosure (1TE)
+
+
+### Power Meter
+
+Developed and tested with:
+
+- Chint DDSU666 Single-Phase Power Meter
+
+The software should also operate with other Modbus RTU compatible power meters after adjusting the communication parameters and register definitions if necessary.
+
+#### Modbus RTU Configuration
+
+The following communication parameters must be configured on the power meter:
+
+| Parameter      | Value                      |
+| -------------- | -------------------------- |
+| Baud Rate      | 9600 (DDSU666: **BAUD-3**) |
+| Data Format    | 8N1                        |
+| Device Address | 008                        |
+
+These settings can also be modified in the source code if different communication parameters are required.
+
+### User Interface
+
+#### OLED Display
+
+The OLED display continuously shows the measured electrical values and is sized to fit within the 1TE enclosure.
+
+<img src="pictures/display.jpg" width="400px">
+
+
+#### Web Interface
+
+The ESP32 operates as a Wi-Fi Access Point with the following default configuration:
+
+- **SSID:** `PWR_METER`
+- **Password:** None (open network)
+- **Web Interface:** `http://192.168.4.1`
+
+The web interface provides:
+
+- Real-time measurements
+- Historical graphical visualization
+- CSV export of measurement data
+
+<img src="pictures/webpage.png" width="600px">
+
+
+## Hardware
+
+### Schematic
+
+The complete wiring schematic is shown below.
+
+<img src="hardware/RS485_OLED_Schaltplan.png" width="600px">
+
+### Enclosure
+
+The original enclosure design is based on the following Thingiverse project:
+
+**D1 Mini DIN Rail Case 1TE, RS485** by Hoich - https://www.thingiverse.com/thing:3337686
+The original design is licensed under: **Creative Commons Attribution – NonCommercial – ShareAlike**
+
+The enclosure has been modified to accommodate the OLED display. Additionally, a second flat enclosure variant has been created for applications where the OLED display is not required.
+
+The modified enclosure is licensed under **CC BY-NC-SA 4.0**, while the original enclosure design remains subject to its original Creative Commons license.
+
+<img src="case/1TE_Case_cleaned.png" width="400px">
+
+<img src="case/1TE_Case_Flat-Case.png" width="400px">
+
+### Assembly
+
+The design does not require a dedicated printed circuit board (PCB).
+
+All components are interconnected using point-to-point wiring inside the 3D-printed enclosure according to the schematic shown above.
+
+<img src="pictures/wiring_1.jpg" width="600px">
+
+<img src="pictures/wiring_2.jpg" width="600px">
+
+
+## Software
+
+### Software Architecture
+
+The software consists of two independent parts:
+
+1. **Firmware**
+
+   - Executes on the ESP32
+   - Reads Modbus RTU measurements
+   - Updates the OLED display
+   - Hosts the web server
+
+2. **Web Resources**
+
+   - HTML
+   - CSS
+   - JavaScript
+   - -> These files are stored in the ESP32 LittleFS filesystem and served by the embedded web server.
+
+The external libraries used by the project are referenced directly in the source code.
+
+### Programming the ESP32
+
+Both the firmware and the web resources must be uploaded.
+
+1. **Step 1 – Upload the LittleFS Filesystem**
+
+    Install the LittleFS extension for Arduino IDE.
+
+    - Download the `.vsix` extension from: https://github.com/earlephilhower/arduino-littlefs-upload/releases/
+    - Copy the downloaded file into:
+    ```
+    C:\Users\<USERNAME>\.arduinoIDE\plugins
+    ```
+    (Create the folder if it does not already exist.)
+
+    Upload the filesystem:
+
+    - Press **CTRL + SHIFT + P**
+    - Select:
+
+    ```
+    Upload LittleFS to Pico/ESP8266/ESP32
+    ```
+
+2. **Step 2 – Upload the Firmware**
+    
+    Upload the ESP32 firmware using the standard **Upload** button in the Arduino IDE.
+
+
+### Software Configuration
+
+If required, the following parameters can be modified in the source code:
+
+- Modbus slave address
+- Baud rate
+- Serial communication settings
+- Supported Modbus register mapping
+- Wi-Fi configuration
+- Display behavior
+
+
+## Sources/Useful Links
+
+- ESP32-C3 Super Mini Pinout: https://sigmdel.ca/michel/ha/esp8266/super_mini_esp32c3_en.html
+- Chint DDSU666 User Manual: https://chint.it/wp-content/uploads/product-docs/iStoragE/Manuali/iStoragE%20Meter%20DDSU666%20User%20Manual%20EN.pdf
+
+- LittleFS support: https://randomnerdtutorials.com/arduino-ide-2-install-esp32-littlefs/
+- The ESP32 firmware and web interface are based on examples from:
+    - https://randomnerdtutorials.com/esp32-websocket-server-sensor/
+    - https://randomnerdtutorials.com/esp32-web-server-gauges/
+    - https://github.com/ChartsCSS/charts.css
+