7.6. Design Example: Dynamic PLL Reconfiguration
Stratix® PLLs allow you to dynamically update PLL coefficients during run time. Each enhanced PLL within the Stratix® device contains a register chain that allows you to modify the pre-scale counters (m and n values), output divide counters, and delay counters. In addition, the ALTPLL_RECONFIG IP core provides an easy interface to access the register chain counters. The ALTPLL_RECONFIG IP core provides a cache that contains all modifiable PLL parameters. After you update all the PLL parameters in the cache, the ALTPLL_RECONFIG IP core drives the PLL register chain to update the PLL with the updated parameters. The figure shows a Stratix® -enhanced PLL with reconfigurable coefficients.
This design example was created using a Nios® II Development Kit, Stratix® Edition. The file sourceprobe_DE_dynamic_pll.zip contains all the necessary files for running this design example, including the following:
- Readme.txt—A text file that describes the files contained in the design example and provides instructions about running the Tk GUI shown in the figure below.
- Interactive_Reconfig.qar—The archived Intel® Quartus® Prime project for this design example.
Figure 110. Interactive PLL Reconfiguration GUI Created with Tk and In-System Sources and Probes Tcl Package
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