Completed Python Logic Circuit Simulator

Project website

Logic gates are interesting, with a few of them you can create circuits with fairly complex functions. Most of the time, the function of the circuit is anything but obvious from just looking at it. For example, consider this one:
That's an adder. You set the inputs A and B to True or False ( 1 or 0), and the circuit will perform a binary addition where S will give you the sum of the two, and C_out the carry bit. The carry bit can then be fed into another full adder at C_in, and you'll also have two more inputs. This can be expanded to any size one wishes.
All currently functioning computers rely on such gates. Most likely, millions and millions of them are in your cellphone.

If you're at least a little familiar with formal logic, more specifically logical connections such as "and", "or", "nor", "xor" (="exclusive or") and so on, the way these circuits work will probably make sense to you very quickly.

I've written a few posts recently about a logic gate simulator I am writing in Python, pyGates. I won't say I finished it, because there are still a few bugs that come up every now and then, but it's far enough along for others to use. Here's a screenshot of what it currently looks like:


You can create new gates by simply dragging them from the left side of the screen, and destroy them by simply dragging them back there. This is actually the only part where I still get bugs every now and then, sometimes cables don't get destroyed properly, but I'll work on fixing this. For now, you can usually work around that by manually deleting the cable - detaching it from the other gate it is connected to, and clicking into empty space.

The website for the project, a zip file with everything you need and the raw source code is located at my website here: http://home.in.tum.de/~dowling/pyGates/.

More pyGates

I'm making some more progress on pyGates, as you can see above. To my surprise, all the logic in the circuits worked out the first time I tested it, which is unusual for my code... Anyway, the logic for the wires has turned out to be much harder than anything else (connecting, disconnecting, reconnecting, in-sockets vs out-out sockets, etc.) I'm close to having it all work out though. Next, I'll have to add functionality to be able to delete Gates, which should be fairly easy. Finally, I'll make the cables look nicer (right now its just a fairly shitty bezier curve, which it will remain, but hopefully less shitty), and then I'll share the source code either on here or on my webpage, since it's really a bit too long to post here in full.

(By the way, the above circuit will constantly change state when you actually build it)

Progress on pyGates

Yesterday I wrote a short paragraph about a project I recently started, a logic gate simulator written in Python (short: pyGates). I spent a night and most of todays classes coding on it, and it's starting to get to a point where it's almost usable. I still need to implement a few more things such as switches and lightbulbs, perhaps I'll add some higher-level logic chips later on, but the basic structure is put together and the wires will also finally behave properly (in terms of connecting to the right sockets and staying there, that is).

Next up is fixing up the graphics, the main thing here is to put in the standardized symbols for the different gates, and making the wires look nice (I'll probably have them hang down as though they were loose cables, similar to logicly). Below is a screenshot of what the program currently looks like (yes, the gates look the same even though they serve different functions).

pyGates

Something I've recently thought about was creating a small logic gate simulator which lets you build simple digital circuits. I've seen this elsewhere before (http://logic.ly/), with a very neat implementation but unfortunately that software now costs money. It shouldn't be too hard to brew something like this together, so I'll give this a shot over the next couple of days and see how it goes. I'll be using python for now just because I like working with it the most, but I might take this as an opportunity to learn JavaScript and host this online. I've already started working on this and have the basic structure together, all it is really is a pygame canvas with gate-objects and a few other things, but it may still take some time until it all comes together in a usable way. I'll keep you posted.