Files
PLFM_RADAR/9_Firmware/9_2_FPGA
Jason 30279e8c4d fix(fpga): F-0.9 option A — BUFIO+BUFR for 50T ft_clkout (SRCC pin)
C4 is an SRCC pin (IS_CLK_CAPABLE=1, IS_MASTER=0 in the Vivado device
model), not an MRCC as earlier comments claimed. SRCC cannot drive BUFG
through dedicated routing, so the previous CLOCK_DEDICATED_ROUTE=FALSE
override forced fabric routing and burned ~5 ns on the ft_clkout path
(WNS -5.362 ns in the d36a4c9 build).

Swap to BUFIO + BUFR for USB_MODE=1 (50T/FT2232H): SRCC → BUFIO → BUFR
is the standard 7-series path for regional clock distribution. All
ft_clkout-domain logic (FT2232H FSM, toggle CDCs, USB FIFO flops) is
contained in bank 35 / one clock region, so regional distribution is
sufficient. USB_MODE=0 (200T/FT601) keeps the BUFG because D17 is a
proper MRCC pin.

Removed CLOCK_DEDICATED_ROUTE=FALSE from both the XDC and the build
script — no longer needed with dedicated BUFIO/BUFR routing.
2026-04-20 20:53:49 +05:45
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