8. Frequency-On-The-Fly for Si5397/96
Some applications require characteristics like input frequency to be modified while leaving clocks from other DSPLLs unaffected. This
Frequency-On-The-Fly functionality is fully supported by Si5397 hardware with the help of CBPro Command Line Interface (CLI) tool.
Frequency-On-The-Fly allows user to:
• Reconfigure the input frequency, output frequency, bandwidth, and LOL/OOF thresholds of a certain DSPLL. The clock output of the
target DSPLL is disabled during the reconfiguration, but the functionalities (for example, freerun, holdover, lock acquisition, hitless
switching) remain the same after it is done.
• Leave all other DSPLLs undisturbed, which means that all clock functions, like phase noise and lock status, remain the same.
Detailed explanation on how to set up Frequency-On-The-Fly with CLI tool is included in these two documents: “CBPro Tools & Support
for In-System Programming” & “CLI User’s Guide”
Figure 8.1. CBPro Tools & Support for In-System Programming
The following steps outline the procedure to initiate Frequency-On-The-Fly:
1. Create CBPro project as base frequency plan.
2. Create text files detailing the input/output frequency, bandwidth, and/or LOL/OOF thresholds of new plans. Plans are defined inde-
pendently for each PLL.
3. Use CLI FOTF tool (create a batch script) to auto generate register files for switching among different plans.
The CLI FOTF tool optimizes the VCO frequency for all of the plans “CLI User’s Guide” includes more in-depth and detailed syntax
explanation and function definition. Example files are bundled in CBPro at C:\Program Files (x86)\Silicon Laboratories\ClockBuilder Pro
\CLI\Samples\FOTF-For-Multi-PLL-Device.
Si5397/96 Reference Manual
Frequency-On-The-Fly for Si5397/96
silabs.com
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