摘要:
Structures and methods to facilitate channel bundling are disclosed. In one embodiment, signal distribution circuitry includes a data path with at least two registers coupled to adjacent sets of data channels in a bundle of data channel sets. In another embodiment, self-switch circuits allow channels in a bundle of channel-sets to switch from bundle-wide signals to locally generated signals after the bundle-wide signals have been synchronously distributed to all channel sets in the bundle. In a particular embodiment, signal distribution circuitry is used to distribute a divided clock signal. In another particular embodiment, signal distribution circuitry is used to distribute enable signals for first-in first-out circuits (“FIFOs”) located in channels of each data channel set in a channel set bundle. In a particular aspect of an embodiment, FIFO read and write operations across a channel set bundle are initiated such that a difference between read and write pointer signals is the same in each channel set.
摘要:
Clock data recovery (CDR) circuitry of a high-speed serial interface on a programmable integrated circuit device toggles, during the electrical idle period of the receiver of the interface, between its “lock-to-reference” (“LTR”) state and its normal “lock-to-data” (“LTD”) state. Whenever during this toggling mode the CDR circuitry toggles to the LTD state, it remains in that state for a predetermined interval and then returns to the LTR state, unless, while it is in the LTD state, it receives a signal from elsewhere in the receiver that data have been received and byte synchronization has occurred. The predetermined toggling interval preferably is long enough to obtain an LTR lock to minimize frequency drift, but short enough to avoid unnecessary delay in detection of the synchronization signal. Preferably, this interval is programmable by the user within limits determined by the characterization of the programmable device. Unreliable analog signal detection is thereby avoided.
摘要:
Clock data recovery (CDR) circuitry of a high-speed serial interface on a programmable integrated circuit device toggles, during the electrical idle period of the receiver of the interface, between its “lock-to-reference” (“LTR”) state and its normal “lock-to-data” (“LTD”) state. Whenever during this toggling mode the CDR circuitry toggles to the LTD state, it remains in that state for a predetermined interval and then returns to the LTR state, unless, while it is in the LTD state, it receives a signal from elsewhere in the receiver that data have been received and byte synchronization has occurred. The predetermined toggling interval preferably is long enough to obtain an LTR lock to minimize frequency drift, but short enough to avoid unnecessary delay in detection of the synchronization signal. Preferably, this interval is programmable by the user within limits determined by the characterization of the programmable device. Unreliable analog signal detection is thereby avoided.