This FAQ provide the guide to router internal oscillator clock to the primary clock network in Radiant.
The “USE PRIMARY" option in Radiant Device Constraint Editor can be used to force-connect non-direct access ports to a primary clock spine through general routing. The specified net should be a clock net.
The USE PRIMARY physical constraint is needed when user intervention is required to route nets using primary and secondary clock resources. PAR uses various criteria for selecting the nets, including the number and type of loads, the availability of clock drivers, and the availability of clock trees.
Device Support
iCE40UP, LIFCL, LFCPNX, LFD2NX, LFMXO5, UT24C, UT24CP, LAV-AT
To set User Primary Net:
1.After opening the design project, choose Tools > Device Constraint Editor.
2.Select the Global tab at the bottom of the view.
3.Double-click the cell beside the ‘Use Primary Net’ and a dialogue will appear.
4.For each available clock, click on the “Selection” drop-down box and select either Primary / Prohibit.