AR# 8258: 2.1i : 9500 : Hitop : WARNING: CPLDFitter- The property SLOW set on the instance "<inst>" conflicts with the previous setting FAST.
AR# 8258
2.1i : 9500 : Hitop : WARNING: CPLDFitter- The property SLOW set on the instance "<inst>" conflicts with the previous setting FAST.
Description
Keywords : 9500, fast, slow, slew
Urgency : standard
General Description:
The 9500 devices have an option to set the slew rate to either fast or slow. In the constraint file you can add the following constraint.
net <name> slow;
When an attempt to implement the design takes place, hitop ignores the constraint with the following warning:
WARNING:CPLDFitter - The property SLOW set on the instance "<inst>" conflicts with the previous setting FAST. Both settings are ignored in favor of the fitter default.
This warning occurs when the design was synthesized from FPGA Express. FPGA Express places FAST attribute on output signals which then confuses the fitter software when it sees a SLOW constraint in the UCF.
解决方案
1
One solution is to
1) Edit Synthesis constraints for FPGA Express 2) Click on the Ports tab 3) Set the slew for the nets in there. 4) The netlist will now have a slow attribute for that net.
2
Another resolution is to manually edit the netlist removing any attribute of 'fast' on that net or replacing it with 'slow'.