188.8.131.52.1. Global Reset Logic
The PLL generates the main clock for this design. All logic, excluding the pcie ip, pr ip, and ddr4 emif run using this 250 MHz clock. The Intel Arria 10/Cyclone 10 Hard IP for PCI Express IP generates the global reset, along with the PLL reset signal. On power up, a countdown timer, tcd2um, counts down using the internal 50 MHz oscillator to a 830 μs delay. Until the timer reaches this delay, the PLL is held in reset, deasserting the locked signal. This action freezes the design. Because the PLL locked signal is ORed with the PCIe* reset, the design also is held in reset. Once the timer reaches 830 μs, the design functions normally, and enters a known state.
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