Duplex Operation Mode Does Not Support Spread Spectrum Clocking Feature

Description

Designs targeting some Cyclone IV GX devices in duplex operation mode and with the Enable Spread Spectrum option turned on may fail to compile.

This issue affects all designs targeting Cyclone IV GX devices -- EP4CGX30 (F484), EP4CGX50, and EP4CGX75 -- with the Enable Spread Spectrum feature option turned on.

The design fails to compile.

Resolution

Use separate SDI RX and TX instances if your design requires the spread spectrum clocking feature.

The Enable Spread Spectrum feature is removed from the 11.0 version of the SDI MegaCore function.