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PoC Testbenches

The PoC-Library can launch manual, half-automated and fully automated testbenches. The testbench can be run in command line or GUI mode. If available, the used simulator is launched with pre-configured waveform files. This can be done by invoking PoC's frontend script: poc.[sh|ps1] and passing the simulator command plus the entity to simulate.

PoC supports the following simulators:

• Cocotb + Mentor Graphics QuestaSim
• GHDL + GTKWave
• Mentor Graphics ModellSim (vSim)
• Mentor Graphics QuestaSim (vSim)
• Mentor Graphics ModellSim Altera Edition (vSim)
• Xilinx ISE Simulator 14.7 (iSim)
• Xilinx Vivado Simulator (xSim)

All Windows command line instructions are intended for Windows PowerShell, if not marked otherwise. So executing the following instructions in Windows Command Prompt (cmd.exe) won't function or result in errors! See the Requirements wiki page on where to download or update PowerShell.

Is PoC already configured on the system? If not, run the following configuration step, to tell PoC which tool chains are installed and where. Follow the instructions on the screen. See the Configuration wiki page for more details.

cd <PoCRoot>
.\poc.ps1 configure

Table of Content:

• Quick Example
• Running a Testbench
• Xilinx ISE Simulator
• Xilinx Vivado Simulator
• Mentor Graphics QuestaSim
• GHDL + GTKwave
• Debugging

---

Quick Example

The following quick example uses the Xilinx ISE Simulator to compile a testbench for the module arith_prng.vhdl (Pseudo Random Number Generator - PRNG). The VHDL file is located at <PoCRoot>/src/arith/ and virtually a member in the PoC.arith namespace. So the module can be identified by an unique name: PoC.arith.prng, which is passed to the testbench script.

Example 1:

cd <PoCRoot>
./poc.sh isim PoC.arith.prng

The CLI option switch isim chooses ISE Simulator (iSim) as the simulator and passes the module name as parameter to the tool. All required source file are gathered and "fused" to an executable. Afterwards this executable is launched in CLI mode and it's outputs are displayed in console:

(click to enlarge)

Example 2:

Passing a second option -g to the testbench tool, opens the testbench in GUI-mode. If a waveform configuration file is present (e.g. *.wcfg files for iSim), then it is preloaded into the simulator's GUI.

cd <PoCRoot>
.\poc.ps1 isim PoC.arith.prng -g

See the red frame in the lower left corner: If everything was ok: SIMULATION RESULT = PASSED is printed onto the simulator console.

(click to enlarge)

Running a Testbench

A testbench is supervised by PoC's <PoCRoot>\py\PoC.py, which offers a consistent interface to all simulators. Unfortunately, every platform has it's specialties, so a wrapper script is needed as abstraction from the host's system. On Windows it's <PoCRoot>\poc.ps1, on Linux and Darwin it's <PoCRoot>/poc.sh.

Darwin (Bash):

cd <PoCRoot>
./poc.sh <common options> <simulator> <module> <simulator options>

Linux (Bash):

cd <PoCRoot>
./poc.sh <common options> <simulator> <module> <simulator options>

Windows (PowerShell):

cd <PoCRoot>
.\poc.ps1 <common options> <simulator> <module> <simulator options>

The service tool offers several common options:

Common Option           Description
----------------------------------------------------------------------
-h   --help             Print a short help
-q                      Quiet-mode (print nothing)
-v                      Print more messages
-d                      Debug mode (print everything)
-D                      Debug wrapper script

One of the following supported simulators can be choosen, if installed and configured in PoC:

command                 Simulator
----------------------------------------------------------------------
asim <module>           Active-HDL Simulator
ghdl <module>           GHDL Simulator
cocotb <module>         Cocotb simulation using QuestaSim Simulator
vsim <module>           QuestaSim Simulator
isim <module>           Xilinx ISE Simulator
xsim <module>           Xilinx Vivado Simulator

GHDL + GTKwave

The command is named ghdl followed by a list of PoC entities. The following options are supported for GHDL:

Option(s)                 Description
----------------------------------------------------------------------
     --board=<BOARD>      Specify a target board.
     --device=<DEVICE>    Specify a target device.
-g   --gui                Start GTKwave, if installed.
                          Open *.gtkw, if available.
     --std=[87|93|02|08]  Select a VHDL standard. Default: 08

Example:

cd <PoCRoot>
.\poc.ps1 -v ghdl PoC.arith.prng --board=Atlys -g

Mentor Graphics QuestaSim

The command is named vsim followed by a list of PoC entities. The following options are supported for ISE Simulator:

Option(s)                 Description
----------------------------------------------------------------------
     --board=<BOARD>      Specify a target board.
     --device=<DEVICE>    Specify a target device.
-g   --gui                Start in GUI-mode.
                          Open *.wdo, if available.
     --std=[87|93|02|08]  Select a VHDL standard. Default: 08

Example:

cd <PoCRoot>
.\poc.ps1 -v vsim PoC.arith.prng --board=Atlys -g

Xilinx ISE Simulator

The command is named isim followed by a list of PoC entities. The following options are supported for ISE Simulator:

Option(s)                 Description
----------------------------------------------------------------------
     --board=<BOARD>      Specify a target board.
     --device=<DEVICE>    Specify a target device.
-g   --gui                Start in GUI-mode.
                          Open a *.wcfg, if available.

Example:

cd <PoCRoot>
.\poc.ps1 -v isim PoC.arith.prng --board=Atlys -g

Xilinx Vivado Simulator

The command is named xsim followed by a list of PoC entities. The following options are supported for Vivado Simulator:

Option(s)                 Description
----------------------------------------------------------------------
     --board=<BOARD>      Specify a target board.
     --device=<DEVICE>    Specify a target device.
-g   --gui                Start in GUI-mode.
                          Open *.wcfg, if available.
     --std=[93|08]        Select a VHDL standard. Default: 93

Example:

cd <PoCRoot>
.\poc.ps1 -v xsim PoC.arith.prng --board=Atlys -g