This page compiles and runs simulation, using GHDL, on a UART transmit module, which I found on the WEB.

1. For a self study project, I needed some DUT. I found this simple UART, written in VHDL.
   For this DUT, I created, as an exercise, a complete specman verification environment. It includes three main parts:
   
   
   
   1. A unit level environment for the TX.
      
   2. A unit level environment for the RX.
      
   3. A full chip environment. The RX part of the DUT drives the TX one. All former code is fully reused to verify the full chip environment.
      The simplicity of connecting and reusing of the code, which was developed for each unit level environment is also shown in this small self study project.


2. The design was compiled using modelsim. At home I use the free VHDL simulator, GHDL. To inspect waves, I use GTKWAVE.


3. To compile it, I needed to slightly modify the TX code and create a nice bash script, adjusted for GHDL.


4. GHDL is more strict than any VHDL compiler I have ever used. So it gave an error if all unsigned library was used. So I had to change the TX code, so only the operators that I use from unsigned library are declared.
   --use IEEE.STD_LOGIC_ARITH.ALL;
     use IEEE.STD_LOGIC_UNSIGNED."+";
   


5. The GHDL bash script is more complex, than the TCL one, which it was originally tested with. The script can be optionally given each of the following switches:
   #clear - removes the compilation directory before start
   #no_comp - skips compilation
   #vcd run with vcd
   #200 run 200 us. This is an optioanlly parameter. Default is 100 us.
   The script is written in bash and uses bash shift command to simplify user input parameters handling.


6. The RX has a very similar script. The RX code can be compiled as is with GHDL.





7. The original code can be downloaded from : original code .
   The GHDL TX - transmit script can be downloaded from : script .
   The GHDL RX - receive script can be downloaded from : script .
   A specman test-bench (eRM) tested with ncsim specman

The script is described in detail in the following link: description .

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