Description

This Answer Record describes how BUFGCE can be useful in operating the SEM IP safely.

Solution

A BUFGCE can be used with the SEM controller clock for a variety of purposes:

• When clock management (PLL,DCM or MMCM) is used, a BUFGCE should be used to suppress the clock toggling to the SEM controller until the clock is stable and the PLL/DCM lock is achieved.
   
• A BUFGCE may be used to disable or delay start-up of the SEM IP during debug.
  With the CE pin initially disabled, the BUFGCE will suppress the clock toggling to the SEM controller.
  The CE pin may be enabled programmatically at run-time by the system to start up the SEM IP.
  Alternatively, the icap_grant input to the SEM IP may be used to achieve the same purpose without disabling the clock.

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