NeoPixel Matrix Simulation Lets You Virtually Groove To The Lights

You are stuck at home quarantined and you want to do some Arduino projects. The problem is you don’t have all the cool devices you want to use. Sure, you can order them, but the stores are slow shipping things that aren’t essential these days. If you want to get a headstart while you are waiting for the postman, check out Wokwi’s Playground. For example, you can write code to drive a virtual NeoPixel 16×16 matrix. There’s even example code to get you started.

There are quite a few other choices in the playground including Charlieplexed LEDs, a keypad, and an LCD. There are also challenges. For example, in the traffic light challenge, you are given code that uses a task scheduler library to implement a traffic light. You have to add a turn signal to the code.

In addition to LEDs in various configurations, the site has some serial bus components, an LCD, a keypad, and a NeoPixel strip. There are also a few tools including an EasyEDA to KiCad converter and a way to share sourcecode similar to Pastebin.

Of course, simulations only get you so far, but the site is a fun way to play with some different I/O devices. It would be very nice if you could compose for the different components together, but you could work your code in sections, if necessary. You can do similar things with TinkerCad circuits. If you want to install software, there’s a simulator for you, too.

Commercial Circuit Simulator Goes Free

If you are looking for simulation software, you are probably thinking LTSpice or one of the open-source simulators like Ngspice (which drives Oregano and QUCs-S), or GNUCap. However, there is a new free option after the closing of Spectrum Software last year: Micro-Cap 12. You may be thinking: why use another closed-source simulator? Well, all the simulators have particular strengths, but Micro-Cap does have very nice features and used to retail for about $4,500.

The simulator boasts a multipage schematic editor, native robust digital simulation, Monte Carlo analysis, 33,000 parts in its library, worst-case and smoke analysis, Smith charts, and it can even incorporate spreadsheets. There’s a built-in designer for active and passive filters. Have a look at the brochure and you will see this is a pretty serious piece of software. And now it’s at least free as in beer.

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Circuit Simulation In Python

Using SPICE to simulate an electrical circuit is a common enough practice in engineering that “SPICEing a circuit” is a perfectly valid phrase in the lexicon. SPICE as a software tool has been around since the 70s, and its open source nature means there are more SPICE tools around now to count. It also means it is straightforward enough to use with other software as well, like integrating LTspice with Python for some interesting signal processing circuit simulation.

[Michael]’s latest project involves simulating filters in LTspice (a SPICE derivative) and then using Python/NumPy to both provide the input signal for the filter and process the output data from it. Basically, it allows you to “plug in” a graphical analog circuit of any design into a Python script and manipulate it easily, in any way needed. SPICE programs aren’t without their clumsiness, and being able to write your own tools for manipulating circuits is a powerful tool.

This project is definitely worth a look if you have any interest in signal processing (digital or analog) or even if you have never heard of SPICE before and want an easier way of simulating a circuit before prototyping one on a breadboard.

Darwin Approves: Berkeley Evolves Analog Design

Digital design is hard. But in the right environment, digital circuits are more forgiving than analog. That 3.3V signal coming out of the chip has to drop a lot along the way to not be a logic level at the destination. If you are trying to push the boundary then digital design has much of analog design, but mostly you get a bit of a pass on many things that plague analog designers. Berkeley’s AI research group has been experimenting with using deep learning to evolve analog IC design.

Analog ICs are plagued with noise sources and often don’t have the margins that digital circuit designers enjoy. According to the post by [Kourosh Hakhamaneshi], designers often build a few blocks and attempt to lay them out in a way that should work and meet other requirements. Then they employ simulation, make changes as required, and simulate again. Accurate simulations can be very time intensive. You can read the actual paper, too, should you want to dig into the details.

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Circuit VR: Advanced Falstad Logic With Geniac

I find that if I’m trying to make a point with a student or a colleague about a circuit, sometimes the Falstad online simulator is worth a few thousand words. You can draw the circuit, play with the values, and even see the current flow in an intuitive way as well as make traditional measurements. The simulator not only handles analog but also digital circuits. At first glance, though, the digital functions appear limited, but if you dig deeper, there is a custom logic block that can really help. I dug into this — and into how switches work in the simulator — the other day in response to a Hackaday post. If you use Falstad, read on!

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Apollo Guidance Computer Saved From The Scrap Yard

NASA needed a small and lightweight computer to send humans on their journey to the Moon and back, but computers of the day were made out of discrete components that were heavy, large, complicated, and unreliable. None of which are good qualities for spaceflight. The agency’s decision to ultimately trust the success of the Apollo program on the newly developed integrated circuit was an important milestone in computer history.

Given the enormity of the task at hand and the monumental effort it took, it’s surprising to learn that there aren’t very many left in existence. But perhaps not as surprising as the fact that somebody apparently threw one of them in the trash. A former NASA contractor happened to notice one of these historic Apollo Guidance Computers (AGC) at an electronics recycling facility, and thankfully was able to save it from getting scrapped.

The AGC was actually discovered in 1976, but it was decided to get the computer working again in time for the recent 50th anniversary of the Moon landing. A group of computer scientists in California were able to not only get the computer up and running, but integrate it into a realistic simulator that gives players an authentic look at what it took to land on the Moon in 1969.

Restoring a computer of this age and rarity is no easy feat. There aren’t exactly spare parts floating around for it, and the team had to go to great effort to repair some faults on the device. Since we covered the beginning stages of the restoration last year, the entire process has been extensively documented in a series of videos on YouTube. So while it’s unlikely you’ll find an AGC in your local recycling center, at least you’ll know what to do with it if you do.

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Spice With A Sound Card

In years gone by, trying out a new circuit probably would have meant heating up a soldering iron. Solderless breadboards have made that even easier and computer simulation is easier still, but there’s something not quite as satisfying about building a circuit virtually. [Thedeuluiz] has a way to get some of the best of both worlds with the RTSpice project.

The idea is simple in concept, although not as simple in execution. The program does a Spice-like simulation of a circuit and can accept input and produce output from a PC’s sound card. Obviously, that means you can’t simulate RF circuits — at least not at the input and the output. It also means the simulation has to run lightning fast to keep up with the sound card sample rate. According to the author, it works best with modest circuits but exactly how big you can go will depend on your hardware.

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