A digital logic designer and circuit simulator

by Donckele • 5 years ago

131 18 5 years ago

sorry i'm a newb in this space (getting into fpga dev through chisel): is this basically ltspice? or is it more powerful? i'm guessing it's more powerful because you can specify asics using vhdl/verilog and you can also export the entire circuit (netlist?) to vhdl/verilog. basically i'm wondering if i can use this to start to understand verilog/vhdl since it could function is a graphical frontend. i'm also wondering if there's more mature tool for that same purpose.

anta40• 5 years ago

Perhaps think of it as Electronics Workbench/Multisim "clone".

etimberg• 5 years ago

I worked at National Instruments on multisim for 4 years. It's fully spice based, whereas this looks like just a digital logic simulator.

retrac• 5 years ago

Spice is primarily an analogue simulator. It can handle audio amplifiers just as well as simulating digital logic circuits.

Digital, as the name implies, doesn't deal with the analogue at all, it's a graphical logic simulator. Step-based, fixed signal values like 1, 0, not connected, high-impedance. Think visual Verilog, except somewhat limited.

There is some support in Digital for defining component behaviour in Verilog or VHDL. Once defined, you will get a graphic symbol you can put in your diagram, and all the wires will behave as specified in the code. It's also possible to translate a schematic in the software to Verilog or VHDL code.

Because of that, I do think it would be a good stepping stone to learning more about logic and hardware description languages. I've recommended it before to people who want to learn the basics. But it's still new, has some limits, and I don't think it would scale well to a large project.

anon_tor_123452• 5 years ago

great. thanks very much clearing that up for me.

Robotbeat2• 5 years ago

This is basically a rewritten Logisim clone which in some ways is cleaner.

There is also Logisim-Evolution, which also supports VHDL/Verilog and FPGA export.

pupdogg• 5 years ago

This reminds me, whatever happened to the hand drawn circuit simulation ink? If anyone recalls, that video went viral back in late 2000s

eatonphil• 5 years ago

This looks great! I was disappointed when Logisim was discontinued but it's good to see there are a number of clones or forks of it now being developed.

marcodiego• 5 years ago

Me too. Logisim possibly needed some clean up or cleaned up rewrite.

Robotbeat2• 5 years ago

Yes, that's basically what this is.

BUT, I've been using Logisim-Evolution, and it is very nice. An expansion of Logisim that, among other things, does VHDL/Verilog and supports a lot of FPGA boards.

dschuetz• 5 years ago

Is this version of logisim any way faster? If it's capable of fully simulating a CPU at 16 Mhz then I'm sold.

ajfjrbfbf• 5 years ago

You can simulate simple CPUs at 100-200 kHz. Faster than Logisim but not in the MHz range.

FullyFunctional• 5 years ago

The fastest open source general digital logic simulator I'm aware off is Verilator, but obviously the speed of simulation depends greatly on the design and whether you are also generating wave forms (for offline viewing)

Donckele2• 5 years ago

Does anyone know of a headless “simplistic” simulator that uses input config files to define wiring and then outputs the state after a “clock tick”?

sasvari2• 5 years ago

Been a while since I've been running this, but you can patch something together with GHDL [0] (or Xilinx's simulation suite (ISim)).

Define your circuit with VHDL/Verilog, create a testbench, run the scripts and export to VCD, and then look at the waveforms with GTKwave [1] or your waveform viewer of choice.

[0] http://ghdl.free.fr/

[1] http://gtkwave.sourceforge.net/

Donckele2• 5 years ago

Hey, thanks for the reply and I have checked out the links briefly. The programs seem pretty heavyweight to what I’m looking for.

peter_d_sherman• 5 years ago

"o Contains a library with the most commonly used 74xx series integrated circuits.

[...]

o Good performance: The example processor can be clocked at 120 kHz.

[...]

o A circuit can be exported to VHDL or Verilog. There is also direct support for the BASYS3 Board and the TinyFPGA BX board. See the documentation for details. The examples folder contains a variant of the example CPU, which runs on a BASYS3 board."

PDS: Looks really nice!

A digital logic designer and circuit simulator

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