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7 Series FPGAs SelectIO Resources User Guide www.xilinx.com 123
UG471 (v1.5) May 15, 2015
IDELAYCTRL
In VHDL, each template has a component declaration section and an architecture section.
Each part of the template should be inserted within the VHDL design file. The port map of
the architecture section should include the design signal names.
IDELAYCTRL
IDELAYCTRL Overview
If the IDELAYE2 or ODELAYE2 primitives are instantiated, the IDELAYCTRL module
must also be instantiated. The IDELAYCTRL module continuously calibrates the
individual delay taps (IDELAY/ODELAY) in its region (see Figure 2-16, page 125), to
reduce the effects of process, voltage, and temperature variations. The IDELAYCTRL
module calibrates IDELAY and ODELAY using the user supplied REFCLK.
IDELAYCTRL Primitive
Figure 2-14 shows the IDELAYCTRL primitive.
IDELAYCTRL Ports
RST - Reset
The reset input pin (RST) is an active-High asynchronous reset. To ensure proper IDELAY
and ODELAY operation, IDELAYCTRL must be reset after configuration and the REFCLK
signal is stable. A reset pulse width T
IDELAYCTRL_RPW
is required.
REFCLK - Reference Clock
The reference clock (REFCLK) provides a time reference to IDELAYCTRL to calibrate all
IDELAY and ODELAY modules in the same region. This clock must be driven by a global
or horizontal clock buffer (BUFG or BUFH). REFCLK must be F
IDELAYCTRL_REF
± the
specified ppm tolerance (IDELAYCTRL_REF_PRECISION) to guarantee a specified
IDELAY and ODELAY resolution (T
IDELAYRESOLUTION
). REFCLK can be supplied directly
from a user-supplied source or the MMCM and must be routed on a global clock buffer.
X-Ref Target - Figure 2-14
Figure 2-14: IDELAYCTRL Primitive
REFCLK RDY
RST
IDELAYCTRL
ug471_c2_12_011811
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