errors · bitdewfpga bit, the XDC check before place and route (nextpnr alone prints the raw lines below)
blink.xdc:27: ERROR [pin-used-twice]: pin U16 is given to 2 ports, clk (blink.xdc:5) and led[0] (blink.xdc:27): one pin takes one port, so nextpnr would stop here. Fix: give each port its own pin: copy their lines from the course's Basys3_Master.xdc (clk is on W5, led[0] is on U16).
blink.xdc:27: ERROR [pin-used-twice]: pin U16 is given to 2 ports, clk (blink.xdc:5) and led[0] (blink.xdc:27): one pin takes one port, so nextpnr would stop here. Fix: give each port its own pin: copy their lines from the course's Basys3_Master.xdc (clk is on W5, led[0] is on U16). https://nosey-dewdrop.github.io/dewfpga/errors/pin-used-twice/nextpnr alone prints a warning and then stops, naming a site instead of a line:
Warning: Conflicting outputs: IO 'led[0]' and IO 'clk' are both constrained to package pin 'U16' (site 'IOB_X0Y3/IOB33/PAD'); only one of them can drive the pad
ERROR: Cell 'clk' cannot be bound to bel 'IOB_X0Y3/IOB33/PAD' since it is already bound to cell 'led[0]'Why does it happen?
A line in the XDC was copied for a new port and its pin was not changed, so two ports ask for one pad. One pad has one driver.
What is the fix?
Give each port its own pin, from the course's Basys3_Master.xdc:
set_property -dict { PACKAGE_PIN W5 IOSTANDARD LVCMOS33 } [get_ports clk]
set_property -dict { PACKAGE_PIN U16 IOSTANDARD LVCMOS33 } [get_ports {led[0]}]