Forum Discussion

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

Critical Warning: Timing requirements not met

hi， these days,I'm learning timing constraints,and I failed to finish to my work. the reports say,from node “ set_ip_req” to node "set_ip_req_r",the slack is -0.818.the launch clock ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

--- Quote Start ---

A 27Mhz clock and 100Mhz clock are not synchronous to each other. You have to cut timing between them, as there's no way the edges will consistently align. Your design either needs to be able to handle that, or you need a circuit that allows the data to go between(hand-shaking, dual-clock FIFO, etc.)

--- Quote End ---

? you mean I can ignore this warning?or use the key word "set timing cut assignment"?