FDT mode3

Renesas FDT officially supports only Boot Mode 2 with separate RX/TX lines. This project allows working in Boot Mode 3, where RX and TX are merged into one MODE line (half-duplex). A Python + Qt5 software bridge converts half-duplex to full-duplex for FDT, filters echo, and manages timing. Communication passes through a virtual COM bridge (com0com) and a USB-to-RS232 adapter (FTDI). Precise timing is critical — latency must be reduced to 3 ms to avoid packet loss. Renesas claims USB adapters don’t work reliably with their bootloader — this project proves the opposite. Tested on one R8C controller; the project is experimental, a second major Python + Qt5 development in progress. ✔️ It works. Stable flashing over USB in Boot Mode 3. Verified.