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Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

Timing Constraint problem on set_input_delay

Hello.

I have encountered problems on the following timing constraint.

The case is draw in the attachment.

I do timing constraint as follows.

creat_generated_clock -add -name {SysClk} -source [get_pins {*|inclk[0]}] [get_pins {*|clk[0]}]

set_input_delay -clock [get_clocks {SysClk}] -max tAO -reference_pin [get_ports {A[0]}] [get_ports {D

[*]}] -add_delay

set_input_delay -clock [get_clocks {SysClk}] -max tAO -reference_pin [get_ports {A[1]}] [get_ports {D

[*]}] -add_delay

set_input_delay -clock [get_clocks {SysClk}] -max tAO -reference_pin [get_ports {A[2]}] [get_ports {D

[*]}] -add_delay

set_input_delay -clock [get_clocks {SysClk}] -max tAO -reference_pin [get_ports {A[3]}] [get_ports {D

[*]}] -add_delay

But the timing constraint is ignored for the reason as said in the tool.

"Reference pin A[0] is invalid.it is not clocked by the clock specified in set_input_delay/set_out_delay's -clock options."

So,why the warning occurs?And how to do timing constraint at this case?

11 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    Here's a text and document I sent to someone else asking about this. It's not as thorough as I'd normally like(which is why I haven't posted it on the wiki or anything like that), but hopefully gets you going. For flash, I've seen people interface to it really slow, in which case the simple method is easiest. They just don't want some enormous outlier. For trying to get it to run as fast as possible, the more complex method is best. Hopefully it helps.