Software EtherCAT Slave on STM32F407VET6 with DP83848 Ethernet PHY

This project implements a fully software-based EtherCAT slave using the SOES (Simple Open EtherCAT Slave) stack on an
STM32F407VET6 microcontroller. Unlike traditional implementations that require a dedicated EtherCAT Slave Controller
chip (such as LAN9252 or ET1100), this project emulates the entire ESC in software using the STM32's built-in Ethernet
MAC and a standard DP83848 PHY.

Key Features:
- Complete EtherCAT Slave Controller emulated in 8KB RAM
- FMMU-based logical-to-physical address translation for process data
- SII/EEPROM emulation in flash for device identification
- EtherCAT datagram processing: APRD/APWR, FPRD/FPWR, BRD/BWR, LRD/LWR/LRW
- CoE (CANopen over EtherCAT) with full Object Dictionary and SDO support
- TwinCAT compatible with included ESI/XML device description file
- 3x digital outputs (LEDs) and 3x digital inputs (buttons) as example I/O
- UART debug