Synthesis Warning: Removing unused instance VDB-5034

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• 1492 - Synplify Pro: How do users prevent the Synplify synthesis tool from removing an unused input pin from my design?

  Users can prevent Synplify from removing an input pin by setting the syn_force_pads synthesis attribute on the input port. Below a Verilog example: input myinput /* synthesis syn_force_pads=1 */; Below a VHDL example: attribute syn_force_pads: ...

• 2214 - Diamond: What is the procedure to prevent unused IO logic from getting optimized out during Synthesis and MAP in Lattice Diamond, while using GUI or Active-HDL batch mode?

  Lattice Diamond tool prevents unused, unconnected IO logic from getting generated, but sometimes user might want to keep a particular IO assignment and the related logic. Below is the procedure to prevent unwanted optimization: add the following ...

• Synthesis warning: Skipping pad insertion on <pin> due to black_box_pad_pin attribute.

  Description: In synthesis, the user may encounter this warning if the synthesis tool skips the IO pad insertion when a 'black_box_pad_pin' attribute is found on the port. Solution: Users may refer to the following from Radiant Help for ...

• 2997 - Lattice Diamond: How does the synthesis tool treat the unused input and output ports declared in the RTL code and not used(logic is not being assigned to the IO Ports)?

  The synthesis tool will remove the unused Input ports declared in the design. For unused Output ports, the tool can either tie them to the GND or leave them tri-stated. You can check this in the RTL view of the Synthesis tool. It is recommended to ...

• 3800 - Diamond: How to prevent the synthesizer from optimizing away any unused I/Os, and still like to have the unused I/Os as placeholder in the design?

  Description: Nets and wires that are not driven will be optimized by the tool to reduce the number of resources during synthesis. In order to place it even if the nets and wires are not driven by any load, attributes syn_keep/noclio, and ...