Monthly Archives: May 2018

Enginursday: Boulder Bounces

via SparkFun: Commerce Blog

SparkFun recently teamed up with the Museum of Boulder to create a new exhibit called Boulder Bounces. It’s a re-creation of our Simon Says Soldering Kit, but using trampolines instead of buttons, and spotlights instead of LEDs.

The purpose of Boulder Bounces is to augment another exhibit called Sportsology, which has interactive areas where people can learn about their own agility and test their strength doing various sports activities. The museum wanted to add something geared toward toddlers to this area.

alt text

Digital mock up from the project proposal

Emily Zinn, their curator of education, had been to SparkFun for a collaboration involving their new makerspace, saw the original Simon Says trampolines and thought they would be the perfect addition!

alt text

The original Simon trampolines - currently located at SparkFun

Amazingly, the original trampolines have survived almost five years since their original Dunk Tank Hack Installation – they have even been on tour across the nation a couple times! They require very little maintenance (mostly cracking wires and LEDs), but I was very excited to create them a second time and improve on the original version.

Lots of improvements

alt text

Control panel with new gameplay modes

We’re most excited about the addition of two new gameplay modes: “Free Bounce” and “Whack A Mole.”

Free Bounce simply lets you jump for fun. You hear a sound and the spotlight fires each time you jump. If there is no jumping for 30 seconds, the exhibit will default into this mode.

Whack a mole is a bit more challenging. It plays just like the old carnival game; when you see a trampoline light up, you jump on it.

If you want to really test your memorization and jumping skills, then you can try Simon Says and memorize up to eight jumps to win!

Another major upgrade was the elimination of the center gap in the trampolines. I have always dreamed of welding a single frame for all of them, but with only three weeks to get this project completed, there simply wasn’t enough time. We found some hexagonal trampolines that fit together quite nicely instead.

alt text

Hexagonal trampolines with no center gap

As with any slight change to a design, this added complexity elsewhere. The custom covers became quite a challenge, but they sure came out looking awesome!

alt text

Custom hexagonal covers

The original installation used exercise trampolines that came with a very handy triggering switch.

alt text

Version 1 mechanical switch

These mechanical momentary switches work really well for most jumpers. However, some of the really lightweight jumpers didn’t cause enough movement to close the switch, and so the occasional jump was missed. To solve this, we switched to a more analog sensing approach, and used the Ultrasonic Sensor.

alt text

Version 2 used Ultrasonic Rangefinders

This allowed for a more precise measurement of the trampoline skin and we could sense even the slightest of movements – no toddler’s jump missed!

The original version involved a lot of hand soldering of wires. A lot of the connections were made directly to the ATMega328 pins on the Simon Says PCB:

alt text

Lots of hand wiring - wait, which ADC did I wire up?

For this new version, I designed a custom PCB to keep things organized.

alt text

Custom PCB design

I’ve had a couple requests from educators for assistance re-creating their own Simon trampolines installation, so I approached this next version with that in mind. I tried to keep it easy to re-create with less point-to-point hand soldering, so it was a little more accessible for a classroom with little soldering or coding experience. I also opted to use a Arduino Pro Mini to keep things easy to replace.

alt text

Some parts wired up during initial development

The ethernet cables (and connectors) also helped cut down on hand wiring connections, but with the addition of the control panels, there was still plenty of soldering to do:

alt text

The inside of the main control panel

The second version also included two more trampolines for the toddlers: “Mighty Mini” and “Hop and Hear.” They both include more sophisticated sounds and the Mighty Mini has a counting feature!

alt text alt text

Two additional trampolines

Design Challenges

One of the most challenging parts of this project, by far, was the fact that we only had three weeks to get it up and running. We underestimated the time needed for most of the installation steps, and did not add in enough buffer for any surprise problems. Bringing in new design techniques (hexagon shapes) and using new technologies (ultrasonic sensors, Tsunami sound boards) added some surprise extra development work that compounded the time crunch.

The first surprise came from the ultrasonic range sensors. I did some testing with two sensors on the old Simon Says installation, so I naively assumed this would be easy. I was able to get good readings from two sensors sequentially, but I didn’t do any testing with two trampolines being jumped on at the exact same time. I later found that when you have two rangefinders in close proximity shooting up at angled surfaces, there can be some really strange readings. The “send” signal from one sensor can incorrectly “echo” its way to the next sensor and cause errors. Ultimately, I was able to tweak the timing of the sequential readings and also filter out some of the erroneous data, but this extra troubleshooting added an extra 4-5 hours of work!

The second surprise came from the Tsunami Super Wav Trigger. I was experiencing some strange behavior - the Tsunami’s boards seemed to be missing triggers, making strange buzzing sounds and eventually crashing. After spending a day and a half troubleshooting, I eventually found that one of my uSD card settings was causing the issue - I had my file allocation size set incorrectly to four kilobytes. After I switched it to 32 kilobytes, my Tsunami boards worked flawlessly.

alt text

Formatting settings for Tsunami uSD card

What would I do differently for version 3?

Plan better for control panel access. Power worked out, but it was tight, and messy. Also, I’d like to have put access to programming lines and volume control without having to remove the front panel. It was stressful to think that it all had to be “perfect” before putting the faces on the panels, and that it’d be a pain to “rip” them off (velcro) for any adjustments.

Related to panel access, I would go with the RedBoard Edge for future designs like this. It has all of the necessary stuff ready to panel mount. We currently offer this via SparkX, and unfortunately it was out of stock while I was developing this.

alt text

RedBoard Edge would have been a good option for my control panels

I also should have made larger holes for cords into the control panels. I was only thinking about the cable diameter fitting through the wall of the frame; this lead to some unplanned drilling and wood shavings all over everything!

Ideally, I would have preferred more time to fine-tune the button control approach. Currently, the Pro Mini is listening to a resistor ladder on a single ADC. This required a fair amount of fine tuning the “windows” and de-bouncing. It currently will miss a very slight button press, but this actually isn’t that common because most participant smack the arcade buttons with all their might!

I would have used a different power solution to avoid the clicking of the beefcake relays - maybe the Lumenati 3x3 array for lighting?

I also should have tested the LED brightness on MODE LEDs - those greens are way too bright! I used 330 ohm resistors on everything, and found that this was way too bright for our 10mm gumdrop greens. Also, the Large 7-segments are pretty darn bright, wish I could have toned those down a bit.

I probably should have used interrupt-based buttons for mode changing, maybe by hooking all the buttons up to an interrupt pin and keeping them connected to their own dedicated GPIO. This way, the interrupt would fire, you could read all pins and know which one was pressed. I was running low on GPIO (in order to keep my custom PCB universal for all three control boards), so I opted for the resistor ladder approach.

Adding LED limiting resistors into the custom PCB design would also have been helpful. It was a pain to wire those from LED lead to bare wire, and I’d hate to change them at this point, but if they were in the PCB design this would have been much easier.

What Next?

We’re thinking about a potential revision to the Noisy Cricket to have screw pin terminals. We had trouble using even some small-gauge speaker wires with the standard 0.1" header breakout PTH pads. We ended up actually putting a screw pin terminal into the headers (as they are), and it gave us access to the GND/MONO-OUT that we needed, but this is less than ideal.

Our current in-house Simon trampolines could use an upgrade. I’m thinking about switching out the gumdrop LEDs for some sort of strips. Our Side-lit LED RGB strips would probably do the trick!

I wasn’t totally satisfied with my mounting approach to proto board. Those PTH headers should hold up, but I’d love to have some more solid standoff holding everything together.

The Tsunami allows you to “pitch bend” sound files, and I’d love to have lighter jumpers have high-pitched sounds, and heavier jumpers have larger, low-pitched sounds (could be especially fun with frog sound bits).

We’re also considering expanding the project into “The Hive” – seven hexagonal trampolines all connected and making sounds. Oh yeah!

Finally, I’d like to explore more lighting techniques. The spotlights came out cool, but I’m curious to know what we could do with lighting systems under the trampolines and custom covers made from a clear material.

Even with all of these potential ideas for Version 3.0, we’re still really stoked on the end result of Boulder Bounces. Every project is a learning experience, and this was definitely not an exception.

We’d also like to send a big thank you to the Museum of Boulder for the opportunity to collaborate on this project! For more info on the museum and all of the other exhibits, please visit

alt text

Boulder Bounces will be on display at the museum for the next three months, so if you get a chance, please come check it out!

For design files and code, visit the GitHub repository here:

Boulder Bounces Github Repository

comments | comment feed

MagPi 70: Home automation with Raspberry Pi

via Raspberry Pi

Hey folks, Rob here! It’s the last Thursday of the month, and that means it’s time for a brand-new The MagPi. Issue 70 is all about home automation using your favourite microcomputer, the Raspberry Pi.

Cover of The MagPi 70 — Raspberry Pi home automation and tech upcycling

Home automation in this month’s The MagPi!

Raspberry Pi home automation

We think home automation is an excellent use of the Raspberry Pi, hiding it around your house and letting it power your lights and doorbells and…fish tanks? We show you how to do all of that, and give you some excellent tips on how to add even more automation to your home in our ten-page cover feature.

Upcycle your life

Our other big feature this issue covers upcycling, the hot trend of taking old electronics and making them better than new with some custom code and a tactically placed Raspberry Pi. For this feature, we had a chat with Martin Mander, upcycler extraordinaire, to find out his top tips for hacking your old hardware.

Article on upcycling in The MagPi 70 — Raspberry Pi home automation and tech upcycling

Upcycling is a lot of fun

But wait, there’s more!

If for some reason you want even more content, you’re in luck! We have some fun tutorials for you to try, like creating a theremin and turning a Babbage into an IoT nanny cam. We also continue our quest to make a video game in C++. Our project showcase is headlined by the Teslonda on page 28, a Honda/Tesla car hybrid that is just wonderful.

Diddyborg V2 review in The MagPi 70 — Raspberry Pi home automation and tech upcycling

We review PiBorg’s latest robot

All this comes with our definitive reviews and the community section where we celebrate you, our amazing community! You’re all good beans

Teslonda article in The MagPi 70 — Raspberry Pi home automation and tech upcycling

An amazing, and practical, Raspberry Pi project

Get The MagPi 70

Issue 70 is available today from WHSmith, Tesco, Sainsbury’s, and Asda. If you live in the US, head over to your local Barnes & Noble or Micro Center in the next few days for a print copy. You can also get the new issue online from our store, or digitally via our Android and iOS apps. And don’t forget, there’s always the free PDF as well.

New subscription offer!

Want to support the Raspberry Pi Foundation and the magazine? We’ve launched a new way to subscribe to the print version of The MagPi: you can now take out a monthly £4 subscription to the magazine, effectively creating a rolling pre-order system that saves you money on each issue.

The MagPi subscription offer — Raspberry Pi home automation and tech upcycling

You can also take out a twelve-month print subscription and get a Pi Zero W plus case and adapter cables absolutely free! This offer does not currently have an end date.

That’s it for today! See you next month.

Animated GIF: a door slides open and Captain Picard emerges hesitantly

The post MagPi 70: Home automation with Raspberry Pi appeared first on Raspberry Pi.

Mycronic MY600 solder paste jet printer first print

via Pololu Blog

Installation of our new Mycronic MY600 that arrived earlier this month is going smoothly. Here are a few pictures and a video from our first test print on a Pololu PCB panel.

Ninoos from Mycronic showing us how to use the MY600 solder paste jet printer.

First Pololu test panel in our new Mycronic MY600 solder paste jet printer.

The gantry is supported only on the left side!

First print on a Pololu PCB panel using Mycronic MY600 solder paste jet printer.

MY600 jet printer first print: Looks like we need a little more solder paste under the central chip and a little less on the leads.

That footage of the jet printer in action is not sped up!

Randomly generated, thermal-printed comics

via Raspberry Pi

Python code creates curious, wordless comic strips at random, spewing them from the thermal printer mouth of a laser-cut body reminiscent of Disney Pixar’s WALL-E: meet the Vomit Comic Robot!

The age of the thermal printer!

Thermal printers allow you to instantly print photos, data, and text using a few lines of code, with no need for ink. More and more makers are using this handy, low-maintenance bit of kit for truly creative projects, from Pierre Muth’s tiny PolaPi-Zero camera to the sound-printing Waves project by Eunice Lee, Matthew Zhang, and Bomani McClendon (and our own Secret Santa Babbage).

Vomiting robots

Interaction designer and developer Cadin Batrack, whose background is in game design and interactivity, has built the Vomit Comic Robot, which creates “one-of-a-kind comics on demand by processing hand-drawn images through a custom software algorithm.”

The robot is made up of a Raspberry Pi 3, a USB thermal printer, and a handful of LEDs.

Comic Vomit Robot Cadin Batrack's Raspberry Pi comic-generating thermal printer machine

At the press of a button, Processing code selects one of a set of Cadin’s hand-drawn empty comic grids and then randomly picks images from a library to fill in the gaps.

Vomit Comic Robot Cadin Batrack's Raspberry Pi comic-generating thermal printer machine

Each image is associated with data that allows the code to fit it correctly into the available panels. Cadin says about the concept behing his build:

Although images are selected and placed randomly, the comic panel format suggests relationships between elements. Our minds create a story where there is none in an attempt to explain visuals created by a non-intelligent machine.

The Raspberry Pi saves the final image as a high-resolution PNG file (so that Cadin can sell prints on thick paper via Etsy), and a Python script sends it to be vomited up by the thermal printer.

Comic Vomit Robot Cadin Batrack's Raspberry Pi comic-generating thermal printer machine

For more about the Vomit Comic Robot, check out Cadin’s blog. If you want to recreate it, you can find the info you need in the Imgur album he has put together.

We ❤ cute robots

We have a soft spot for cute robots here at Pi Towers, and of course we make no exception for the Vomit Comic Robot. If, like us, you’re a fan of adorable bots, check out Mira, the tiny interactive robot by Alonso Martinez, and Peeqo, the GIF bot by Abhishek Singh.

Mira Alfonso Martinez Raspberry Pi

The post Randomly generated, thermal-printed comics appeared first on Raspberry Pi.

Experimenting with 3D Printing on Fabric

via SparkFun: Commerce Blog

I’ve been seeing a lot of 3D printing on fabric around on the internet lately. I found this technique extremely intriguing based on my interests in wearables and combining tech and craft, and I was excited to try it using our Lulzbot printers.

Before we jump in, I want to give credit to my inspiration. There have been tons of similar projects, but most credit for the development of this technique can go to David Shorey, who wrote about his work in Make Magazine. His work definitely piqued my interest, but I really decided to give it a go when I saw this necklace on imgur. I loved the idea of not only using this to make a scaling malleable surface, but also to create a visual floating effect against the skin.

I started my experiments by following the processes I read about online. It’s pretty straight forward but it does take some finesse. If it was broken down into a step-by-step format it might look something like this:

  1. Make/download a model and prepare the g-code for the printer
  2. Start the print
  3. Pause the print after 2-3 layers have been printed
  4. Manually move the Z-axis up
  5. Stretch the fabric over the printed materials
  6. Manually move the Z-axis back down to one position above where it was before you lifted it
  7. Resume print
    (All prints used standard print settings for the LulzBot Taz 5 with 2.85 mm ABS. G-code was generated using Cura.)

I decided to start making some floating bracelets. The first design was super simple, and was mostly a test to see if my general idea would work. You will notice I used tiny magnets for my clasp, which worked really well.

3D printed bracelet

3D printed bracelet

alt text

I wanted to make the design a bit more whimsical, so I put a model together with a handful of floating stars. This is where things started to get a little… annoying. It turns out that their sharp angles were having a hard time sticking to the print bed. When the nozzle made a sharp turn, it would start to pick up the filament it had just laid down with it, making a big mess of melted plastic. Because I am not a quitter, I managed to “successfully” print a pared-down version of the design after close to 30 attempts, but it was pretty clear that this direction was not the best for this technique on the printer I was using (calling it a success is a stretch because the print had a few holes and some stars in the model didn’t make it during the final print.)

3D printed bracelet

alt text

The shapes needed to be more simple, making them easier to print and stick to the bed. At this point I started wondering if I could get just a simple pulsing LED into my printed modules using a super bright white LED, LilyTiny, small battery, JST connector, resistor and a piece of protoboard. I decided that if I included some electronics, each module should be self contained as to avoid shattering the illusion of floating object with wires or conductive thread.

I started this leg of my experimentation by getting a rough idea of how much space a simple circuit and battery might take up and printing a loose design. Something I noticed right away was that the delicate fabric cannot withstand a super bulky module.

3d Printing test

I tried to minimize the size by replacing the super-bright white LED with a flat LilyPad LED. Unfortunately this guy wasn’t bright enough. I decided to let go of the pulsing of the LED to bring down the height of the circuit without compromising brightness, and just go with a a battery, resistor (hidden underneath the protoboard), LED and JST connector to make the smallest circuit possible. Below is an image of my circuit progression.

circuit iteration

I went through a bunch of iterations with the module design off fabric first, to nail it down before needlessly wasting fabric materials. The module needed to be in two parts - a base and a cap - so that I could easily put the electronics inside, plug the battery into the JST connector for use, access the battery connector for recharging and so on. I probably went through about 10 iterations before I finalized my design. In a few cases I made my walls too thin, and in some too thick. I initially planned to use magnets to secure the two parts of a module, but this meant making the walls a lot thicker than I wanted too.

3D printing mistakes

I eventually managed to create a design that would simply use pressure to hold the top and bottom together. I decided to hide the battery in the base to save on some space and keep it secure.

electronics module

electronics module

electronics module

Once I nailed everything down as a free-standing module, I moved on to print on fabric. With all the practice from my previous experiments, I was able to execute a few clean fabric prints pretty quickly. The final result of several electronics modules on fabric looks pretty ok, but I think could be refined a lot more.

final 3D print

final 3D print

I learned a few things about 3D printing on fabric as I developed my designs and tested them out.

First, if you’re thinking about printing on fabric, before you incorporate the fabric, print two to three layers first. One layer is not enough; four is probably too much. Second, the fabric needs to be SUPER taught, especially if it’s a cheap nylon like I was using. If the nozzle even grazes the fabric, it will burn a massive hole and basically ruin your entire print. I lost a lot of good fabric to the nozzle drag, which brings me to my third lesson: Don’t bring the Z-axis back down to its original position, but rather one notch above where it had been. The melted extruded plastic will still stick to the layers below and you won’t risk burning your fabric as much with that extra space.

The image below illustrates the technique I used to stretch the fabric on the print bed. I used a combination of binder clips on the edges with some masking/painters tape on the bed to keep the fabric flat against it.

taught fabric

I’m pleased with what I discovered during this process, but I definitely think I could spend a few more weeks finessing the incorporation of electronics - both on the hardware end and on the model design. I definitely think this is the kind of project that might require some custom PCB design, which is a good next step for me!

If you are interested in setting up your own 3D printing work space, check out our 3D printing tools. If you are interested in 3D printing but don’t have a printer, check out your local library or makerspace! If all else fails, you can always order prints online from companies like Shapeways.

Let us know what you think about 3D printing on fabric in the comments below!

comments | comment feed

Arduino time attendance system with RFID

via Dangerous Prototypes


A how-to on building a time attendance system with MFRC522 RFID Reader and Arduino from Random Nerd Tutorials:

Before getting started it’s important to layout the project main features:
*It contains an RFID reader that reads RFID tags;
*Our setup has a real time clock module to keep track of time;
*When the RFID reader reads an RFID tag, it saves the current time and the UID of the tag in an SD card;
*The Arduino communicates with the SD card using an SD card module;
*You can set a check in time to compare if you are in time or late;
*If you are on time, a green LED lights up, if you are late, a red LED lights up;
*The system also has a buzzer that beeps when a tag is read.

More details at

Check out the video after the break.