The XC7A50T-FTG256 has only 69 usable IO pins but radar_system_top
declares 182 port bits. Previous attempts to remove unconstrained
ports via TCL caused opt_design to cascade-remove all driving logic.
New approach: radar_system_top_50t.v is a thin wrapper that:
- Exposes only the 64 physically-connected ports (ADC, DAC, SPI, clocks)
- Instantiates radar_system_top internally with full logic preserved
- Ties off unused inputs (FT601 bus, ext trigger) to safe defaults
- Leaves unused outputs internally connected (no IOBs created)
Updated build_50t_test.tcl to use radar_system_top_50t as top module
and removed the now-unnecessary port removal TCL code.