Description
The ALTDDIO_OUT megafunction uses a multiplexer where the select pin is driven with a clock signal, and the inputs are two registers with a 1 and 0 connected to the data pins. This structure is implemented using a dedicated circuit in the device Input/Output Element (IOE).
The paths from these registers to the mux are guaranteed to close timing when the path from the clock to the output does so only this path is analyzed in the TimeQuest™ Timing analyzer.