26 lines
1.0 KiB
ReStructuredText
26 lines
1.0 KiB
ReStructuredText
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.. _file_format_pin_constraints_file:
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Pin Constraints File
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--------------------
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The *Pin Constraints File* (PCF) aims to create pin binding between an implementation and an FPGA fabric
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An example of design constraints is shown as follows.
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.. code-block:: xml
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<pin_constraints>
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<set_io pin="clk[0]" net="clk0"/>
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<set_io pin="clk[1]" net="clk1"/>
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<set_io pin="clk[2]" net="OPEN"/>
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<set_io pin="clk[3]" net="OPEN"/>
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</pin_constraints>
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.. option:: pin="<string>"
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The pin name of the FPGA fabric to be constrained, which should be a valid pin defined in OpenFPGA architecture description. Explicit index is required, e.g., ``clk[1:1]``. Otherwise, default index ``0`` will be considered, e.g., ``clk`` will be translated as ``clk[0:0]``.
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.. option:: net="<string>"
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The net name of the pin to be mapped, which should be consistent with net definition in your ``.blif`` file. The reserved word ``OPEN`` means that no net should be mapped to a given pin. Please ensure that it is not conflicted with any net names in your ``.blif`` file.
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