6441 - PLL for Nexus FPGAs: How to dynamically change the PLL output frequency?
Description:
On FPGA-TN-02095, locate Appendix C. PLL LMMI Operation.
The user can access the PLL dynamic parameters through the use of LMMI (Lattice Memory Mapped Interface).
Solution:
If the user wants to vary the output frequency (for example CLKOP frequency), the user need to modify the value of lmmi_divn (n = a,b,c,d,e,f wherein a is for clkop, b for clkos and so on).
Once the necessary offset address is written with the desired value, the user must write 1 to the Shadow_Reg_Update to propagate the changes.
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