Worst slack values are Negative for Removal

HI ,

I modified the constraint file with this :

# Update -period with clock period (in nanoseconds) of the clock driving the fpga

create_clock -name sopc_clk -period 20 [get_ports PLD_CLOCKINPUT]

# Setting LED outputs as false path, since no timing requirement

set_false_path -from * -to [get_ports LEDG

[*]]

# Constraining JTAG interface# TCK port

create_clock -name altera_reserved_tck -period 100 [get_ports altera_reserved_tck]# cut all paths to and from tck

set_clock_groups -exclusive -group [get_clocks altera_reserved_tck]# constrain the TDI port

set_input_delay -clock altera_reserved_tck 20 [get_ports altera_reserved_tdi]# constrain the TMS port

set_input_delay -clock altera_reserved_tck 20 [get_ports altera_reserved_tms]# constrain the TDO port

set_output_delay -clock altera_reserved_tck 20 [get_ports altera_reserved_tdo]

# JTAG Signal Constraints constrain the TCK port

create_clock -name tck -period 100 [get_ports altera_reserved_tck]# Cut all paths to and from tck

set_clock_groups -asynchronous -group [get_clocks altera_reserved_tck]# Constrain the TDI port

set_input_delay -clock altera_reserved_tck -clock_fall 1 [get_ports altera_reserved_tdi]# Constrain the TMS port

set_input_delay -clock altera_reserved_tck -clock_fall 1 [get_ports altera_reserved_tms]# Constrain the TDO port

set_output_delay -clock altera_reserved_tck -clock_fall 1 [get_ports altera_reserved_tdo]

but still the worst slack time for removal is negative.

altera_reserved_tck 0.000 0.000 0.000 -2.347 0.000

Design-wide TNS 0.0 0.0 0.0 -2.347 0.0

altera_reserved_tck 43.109 0.181 42.831 -2.347 29.289 Worst-case Slack 6.011 0.082 3.704 -2.347 9.550

But it says that:

# Update -period with clock period (in nanoseconds) of the clock driving the fpga

Should nt we put the value in nanosec?