Vision VHD-800 Spezifikationen PDF herunterladen (Seite 18)

Be aware of the fact that the compilation steps will take longer and longer. The compiler has to push all its efforts to the

limit for increasing constraints!

7 Example IV: Magnitude Comparator

Our ﬁnal example is located in the source ﬁle ./sourcecode/comparator.vhd and is a purely combinational 4-bit magnitude

comparator.

Student Task 15:

• Have a look at the VHDL code. Two binary inputs are compared to each other. If the ﬁrst number is equal,

smaller, or larger than the second number, separate outputs are set accordingly.

• Now, synthesize the code and investigate the log, reports and resulting netlist. Note that while elaborating

the VHDL ﬁle, you have to set the parameter WIDTH : set it to 4 (Hint: elaborate <design_name> \

-parameters "<parameters> = XX").

• Are there some additional cells, which you had not intended?

• Correct the source code such as to prevent those cells from being inferred. After having changed the source

code, you have to perform an RTL simulation to verify the correct functionality of it. For that, we have already

prepared a testbench, which is located at ./sourcecode/comparator tb.vhd. For the simulation, you can use the

script located at ./modelsim/comparator compile rtl.csh

• Show your source code correction and the simulation results to an assistant.

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Vision VHD-800 Spezifikationen Seite 18