Using the PLL Clock Calculator
The PLL Clock Calculator provides a graphical way for you to set up the advanced PLL block. When you open the calculator, the GUI appears in automatic mode, which provides basic settings. You can:
- Choose the feedback mode (Local, Core, or External).
- Turn signals on (gray x) or off (green arrow) by clicking the icons next to the signal.
- Specify the signal names.
- Specify the phase shift.
- Choose which clock has feedback (for core feedback mode).
The Topaz PLL supports dynamic phase shifting. To enable it, click the Dynamic button for the clock output. The calculator adds three additional pins that you use to control the dynamic shifting. You need to specify the pin names.
As you make selections, the calculator determines the values for the pre-divider, multiplier, post divider, and clock dividers that meet your settings. The GUI prompts you if you make selections that are impossible to solve.
In manual mode, the interface displays the PLL's internal block diagram, and provides boxes for you to set the values for the pre-divider, multiplier, post divider, and clock dividers. As you adjust the values, the calculator prompts you if you make settings that result in FVCO values that are out of range or are impossible to solve. When you turn manual mode off, the calculator adjusts the output clock frequencies to match the manual settings. If you have incorrect settings for the pre-divider, multiplier, post divider, and clock dividers, when you turn manual mode off, the calculator adjusts the values to ones that allow a valid solution.
When you are finished using the calculator, click Finish to save your settings and close the GUI.