Cyclone® V Hard Processor System Technical Reference Manual

ID 683126
Date 8/28/2023
Public
Document Table of Contents

3.3.2. Hardware-Managed and Software-Managed Clocks

When changing values on clocks, the terms hardware-managed and software-managed define who is responsible for successful transitions. Software-managed clocks require that software manually gate any clock affected by the change, wait for any PLL lock if required, then ungate the clocks. Hardware-managed clocks use hardware to ensure that a glitch-free transition to a new clock value occurs. There are three hardware-managed sets of clocks in the HPS, namely, clocks generated from the main PLL outputs C0, C1, and C2. All other clocks in the HPS are software-managed clocks.