Pi

68 Articles

A Pi Calculating Pi For Pi Day

March 14, 2023 by 12 Comments

What is it about pi that we humans — at least some of us — find so endlessly fascinating? Maybe that’s just it — it’s endless, an eternal march of digits that tempts us with the thought that if we just calculate one more digit, something interesting will happen. Spoiler alert: it never does.

That doesn’t stop people from trying, of course, especially when “Pi Day” rolls around on March 14 every day  — with apologies to the DD/MM set, of course. This year, [Cristiano Monteiro] commemorated the day with this Pi-based eternal pi calculator. The heart of the build is a Raspberry Pi Pico board, which does double duty thanks to its two cores. One core is devoted to running the pi calculation routine, while the other takes care of updating the seven-segment LED display with the last eight calculated digits. Since the calculation takes increasingly more time the farther into pi it gets, [Cristiano] thoughtfully included a 1-Hz heartbeat indicator, to assure users that the display isn’t frozen; the video below shows how slow the display gets even just a few seconds after starting up, so it’s a welcome addition.

This is actually [Cristiano]’s second go at a Pi Day pi calculator; last year’s effort was a decidedly tactical breadboard build, and only supported a four-digit display. We applaud the upgrades, and if anyone wants to replicate the build, [Cristiano] has posted his code.

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Hackaday Links: November 6, 2022

November 6, 2022 by 20 Comments

Remember the chip shortage? We sure do, mainly because as far as we can tell, it’s still going on, at least judging by the fact that you can’t get a Raspberry Pi for love or money. But that must just be noise, because according to a report in the Straits Times, the chip shortage is not only over, it’s reversed course enough that there’s now a glut of semiconductors out there. The article claims that the root cause of this is slowing demand for products like smartphones, an industry that’s seeing wave after wave of orders to semiconductor manufacturers like TSMC canceled. Chips for PCs are apparently in abundance now too, as the spasm of panic buying machine for remote working during the pandemic winds down. Automakers are still feeling the pinch, though, so much so that Toyota is now shipping only one smart key with new cars, instead of the usual two. So there seems to be some way to go before balance is restored to the market, but whatever — just call us when Amazon no longer has to offer financing on an 8 GB Pi.

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It’s Pi All The Way Down With This Pi-Powered Pi-Picking Robot

September 20, 2022 by 14 Comments

While most of us live in a world where the once ubiquitous Raspberry Pi is now as rare as hens’ teeth, there’s a magical place where they’ve got so many Pis that they needed to build a robotic dispenser to pick Pi orders. And to add insult to injury, they even built this magical machine using a Raspberry Pi. The horror.

This magical place? Australia, of course. There’s no date posted on the Pi Australia article linked above, but it does mention that there’s a Pi 4 Model B running the show, so that makes it at least recent-ish. Stock is stored in an array of tilted bins that a shuttle mechanism accesses via an X-Y gantry. The shuttle docks in front of a bin and uses a stepper-controlled finger to flip a box over the lip holding them in its bin. Once in the shuttle, the order is transported to an array of output bins, where a servo operates a flap to unceremoniously dump the product out for packing and shipping. There’s a video of a full cycle below, but a word of warning — the stepper motors on the X-Y gantry really scream, so you might want to lower the volume.

The article goes into more detail on not only the construction of “Bishop” — named after the heroic synthetic organism from Aliens — but also the challenges faced during construction. It turns out that even when you try to use gravity to simplify a system like this, things can go awry very easily. There’s also a fair bit of detail on the software, which surprisingly centers around LinuxCNC. And there are plans to take this further, with another bot to do the packing, sealing, and labeling of the order. If they need all that automation down there, we guess we found all the missing Pis.

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Calculating Pi On The 4004 CPU, Intel’s First Microprocessor

April 15, 2022 by 26 Comments

These days we are blessed with multicore 64-bit monster CPUs that can calculate an entire moon mission’s worth of instructions in the blink of an eye. Once upon a time, though, the state of the art was much less capable; Intel’s first microprocessor, the 4004, was built on a humble 4-bit architecture with limited instructions. [Mark] decided calculating pi on this platform would be a good challenge. 

It’s not the easiest thing to do; a 4-bit processor can’t easily store long numbers, and the 4004 doesn’t have any native floating point capability either. AND and XOR aren’t available, either, and there’s only 10,240 bits of RAM to play with. These limitations guided [Mark’s] choice of algorithm for calculating the only truly round number. Continue reading “Calculating Pi On The 4004 CPU, Intel’s First Microprocessor” →

Thermal printer with a loop of thermochromic foil inserted in it, printing digits of Pi on the loop.The digits gradually disappear from the foil as it exits the printer.

Celebrating The Infinity Of Pi Day With Thermochromic Foil

March 21, 2022 by 8 Comments

It might take you some time to understand what’s happening in the video that Hackaday alum [Moritz Sivers] shared with us. This is [Moritz]’s contribution for this year’s Pi Day – a machine that shows digits of Pi in a (technically, not quite) infinite loop, and shows us a neat trick we wouldn’t have thought of.

The two main elements of this machine are a looped piece of thermochromic foil and a thermal printer. As digits are marked on the foil by the printer’s heating element, they’re visible for a few seconds until the foil disappears from the view, only to be eventually looped back and thermally embossed anew. The “Pi digits calculation” part is offloaded to Google’s pi.delivery service, a π-as-a-Service endpoint that will stream up to 50 trillion first digits of Pi in case you ever need them – an ESP8266 dutifully fetches the digits and sends them off to the thermal printer.

This machine could print the digits until something breaks or the trillions of digits available run out, and is an appropriate tribute to the infinite nature of Pi, a number we all have no choice but to fundamentally respect. A few days ago, we’ve shown a similar Pi Day tribute, albeit a more self-sufficient one – an Arduino calculating and printing digits of Pi on a character display! We could’ve been celebrating this day for millennia, if Archimedes could just count a little better.

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Simple Arduino Build Lets You Keep An Eye On Pi

March 15, 2022 by 10 Comments

Are you a math aficionado in need of a new desk toy? Then do we have the project for you. With nothing more than an Arduino and a seven-segment LED module, [Cristiano Monteiro] has put together a little gadget that will slowly work its way through the digits of Pi forever…or until you get bored of looking at it and decide to use the parts for something else.

On the hardware side, we really can’t overstate how simple this project is. A common four-digit LED display is connected up to an Arduino Nano, which is then plugged into the computer for power. [Cristiano] is using a breadboard here, but you could just as easily use four female-to-female jumpers to connect the two devices together. We suppose this would be a pretty good project for anyone who’s looking to get some practical experience with PCB design as well.

The real magic is in the software, which [Cristiano] has been kind enough to release under the MIT license. Calculating Pi on such a resource-constrained chip as the ATmega328P is far from ideal, but by porting over a C++ algorithm developed by [Xavier Gourdon] and [Pascal Sebah] for their paper Computation of the n-th Decimal Digit of π with Low Memory he was able to pull it off, albeit slowly.

Now if you’ve got slightly better hardware, say a pair of Xeon processors and 96 GB of RAM, you could calculate Pi out to a few trillion digits for fun, but it wouldn’t look as cool as this little guy blinking away.

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You Can Send MIDI Over I2C If You Really Need To

February 15, 2022 by 11 Comments

The Musical Instrument Digital Interface has a great acronym that is both nice to say and cleanly descriptive. The standard for talking to musical instruments relies on a serial signal at 31250 bps, which makes it easy to transmit using any old microcontroller UART with a settable baud rate. However, [Kevin] has dived into explore the utility of sending MIDI signals over I2C instead.

With a bit of hacking at the Arduino MIDI library, [Kevin] was able to get the microcontroller outputting MIDI data over the I2C interface, and developed a useful generic I2C MIDI transport for the platform. His first tests involved using this technique in concert with Gravity dual UART modules. After he successfully got one running, [Kevin] realised that four could be hooked up to a single Arduino, giving it 8 serial UARTS, or, in another way of thinking, 8 MIDI outputs.

At its greatest level of development, [Kevin] shows off his I2C MIDI chops by getting a single Raspberry Pi Pico delivering MIDI signals to 8 Arduinos, all over I2C. All the Arduinos are daisy-chained with their 5V and I2C lines wired together, and the system basically swaps out traditional MIDI channels for I2C addresses instead.

There’s not a whole lot of obvious killer applications for this, but if you want to send MIDI data to a bunch of microcontrollers, you might find it easier daisy-chaining I2C rather than hopping around with a serial line in the classic MIDI-IN/MIDI-THRU fashion.

We’ve seen [Kevin]’s work before too, like the wonderful Lo-Fi Orchestra. Video after the break.

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