Clocking - 1.1 English

AXI4-Stream Infrastructure IP Suite (PG085)

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1.1 English

Each AXI4-Stream Infrastructure IP module has a single clock input that must be driven with the exception of AXI4-Stream Clock Converter and AXI4-Stream Data FIFO. These modules allow for different clocks and must have both S_AXIS_ACLK and M_AXIS_ACLK connected.

The AXI4-Stream Clock Converter and Data FIFO allows systems with different clock domains to be designed. AXI4-Stream Clock Converter synchronous mode can be used when the endpoint IP has a phase-aligned, integer multiple clock ratio to the core switch's clock. This is often the case when the same MMCM or PLL is driving synchronous integer ratio clocks because the MMCM/PLL can also ensure phase alignment across their clock outputs. The AXI4-Stream Clock Converter and AXI4-Stream Data FIFO asynchronous clocking mode allows the attached endpoint IP to run at a completely unrelated clock frequency or phase to the core switch clock.

TIP:   To ease timing closure always drive synchronous clocks with the MBUFG primitive when possible. The MBUFG primitives can provide related clocks with ratios of 2, 4, or 8 by using a clock divider within the buffer. This primitive is available on Versal devices.

An optional feature for clock enables (ACLKEN ports) allows an extra level of control for essentially gating clocks. The clock enable signals can be used to control which clock edges are seen as real transfer cycles. Clock enables can be used for purposes like preserving global clock buffers, debug by stepping the clock enable to step through operational states in the system, and dynamic power savings. Clock enables can be controlled independently on each interface port and for the core switch.

The optional AXI4-Lite control register interface operates asynchronously from the AXI4-Stream clocks.