Files
NawfalMotii79-PLFM_RADAR/9_Firmware
Jason 9f3eb756f9 build(mcu): add linker script + USB CDC glue (PR 2 — firmware links)
Closes the link for the STM32F746ZGT7 bring-up:

- linker/STM32F746ZGTx_FLASH.ld: 1 MB flash @ 0x08000000, 256 KB RAM @
  0x20010000 (SRAM1+SRAM2 contiguous), 64 KB DTCM for stack/heap, 16 KB
  ITCM. Standard Cube-style section layout.
- 9_1_3_C_Cpp_Code/usb_device.{h,c}: MX_USB_DEVICE_Init wiring CDC class
  + interface into hUsbDeviceFS.
- 9_1_3_C_Cpp_Code/usbd_conf.{h,c}: HAL PCD bridge — hpcd_USB_OTG_FS,
  USBD_LL_* callbacks, HAL_PCD_MspInit (PA11/PA12 AF10, OTG_FS clock,
  OTG_FS_IRQn), static allocator for USBD_malloc.
- 9_1_3_C_Cpp_Code/usbd_desc.{h,c}: device + string descriptors, VID
  0x0483 / PID 0x5740 (STM32 VCP), serial derived from 96-bit UID.
- 9_1_3_C_Cpp_Code/usbd_cdc_if.{h,c}: CDC_Transmit_FS + class callbacks;
  host-to-device bytes forwarded via weak CDC_on_receive hook so
  USBHandler can override from C++ without a hard dep.

Makefile:
- default target now 'link' (produces firmware.elf/.bin/.hex).
- APP_CPP no longer excludes main.cpp; LIB_CPP no longer excludes
  gps_handler.cpp.
- USB_C picks up Core + CDC class .c files (minus *_template.c).
- Drops vendor system_stm32f7xx.c — the app-customised copy in
  9_1_1_C_Cpp_Libraries/ is the real one; keeping both caused duplicate
  symbols.

Incidental fixes to main.cpp (pre-existing bugs exposed by first real
compile):
- DIAG_GPIO at main.cpp:662-663 was called with 3 args; macro takes
  (subsys, name, port, pin). Passed the STATUS0/STATUS1 port+pin pair.
- PI used at main.cpp:1589-1594 for atan2 conversions but never
  defined. Added a local #define PI 3.14159265358979323846f near the
  top of the file.

Result: firmware.elf = 118 548 B text / 776 B data / 12 672 B bss.
Fits comfortably in 1 MB flash; DTCM stack/heap clears 64 KB with room.
2026-04-23 07:53:41 +05:45
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