Bug 1 (FPGA): status_words[0] was 37 bits (8+3+2+5+3+16), silently
truncated to 32. Restructured to {0xFF, mode[1:0], stream[2:0],
3'b000, threshold[15:0]} = 32 bits exactly. Fixed in both
usb_data_interface_ft2232h.v and usb_data_interface.v.
Bug 2 (Python): radar_mode extracted at bit 21 but was actually at
bit 24 after truncation — always returned 0. Updated shift/mask in
parse_status_packet() to match new layout (mode>>22, stream>>19).
Bug 3 (STM32): parseFromUSB() minimum size check was 74 bytes but
9 doubles + uint32 + markers = 82 bytes. Buffer overread on last
fields when 74-81 bytes passed.
All 166 tests pass (29 cross-layer, 92 GUI, 20 MCU, 25 FPGA).
Three-tier test orchestrator validates opcode maps, bit widths, packet
layouts, and round-trip correctness across FPGA RTL, Python GUI, and
STM32 firmware. Catches 3 real bugs:
- status_words[0] 37-bit truncation in both USB interfaces
- Python radar_mode readback at wrong bit position (bit 21 vs 24)
- RadarSettings.cpp buffer overread (min check 74 vs required 82)
29 tests: 24 pass, 5 xfail (documenting confirmed bugs).
4th CI job added: cross-layer-tests (Python + iverilog + cc).
Jason