You may observe these unexpected rx_freqlocked and rx_signaldetect signal behaviors due to incorrect Signal Detect circuit settings in Quartus® II 10.1 software for Cyclone® IV GX devices. To workaround this issue, install the following patch, re-generate the Megawizard™ files and re-compile the design.
- Download the version 10.1 patch 0.08 for Windows (.exe)
- Download the version 10.1 patch 0.08 for Linux (.tar)
- Download the Readme for the Quartus II software version 10.1 patch 0.08 (.txt)