PIC Mesh, Accessible Distributed Networking

Wireless networks have been reduced to a component, for most of us. We fit a device, maybe an ESP8266 module or similar, and as if by magic a network exists. The underlying technology has been abstracted into the firmware of the device, and we never encounter it directly. This is no bad thing, because using wireless communication without having to worry about its mechanics gives us the freedom to get on with the rest of our work.

It is however interesting once in a while to take a look at the operation of a real wireless network, and [Alex Wong], [Brian Clark], and [Raghava Kumar] have given us a project with the opportunity to do just that. Their PIC Mesh university project is a distributed wireless mesh network using 2.4GHz NRF24L01 transceiver modules and PIC32 microcontrollers. They have it configured for demonstration purposes with a home automation system at the application layer, however it could be applied to many other applications.

The real value in this project is in its comprehensive but easy to read write-up of the kind you’d expect from a university project. The front page linked above has an overview of how the mesh works, but there are also pages taking us through the hardware, the networking software layer, and the home automation application layer. If you have ever wanted to understand a simple mesh networking system, this is a good place to start.

We’ve covered quite a few mesh networks over the years, but sadly we can only link you to a few of them. We’ve had a mesh network using the Raspberry Pi, Project Byzantium’s “ad-hoc wireless mesh networking for the zombie apocalypse“, and a 1000-node Xbee network for testing purposes.

My Life in the Connector Zoo

“The great thing about standards is that there are so many to choose from.” Truer words were never spoken, and this goes double for the hobbyist world of hardware hacking. It seems that every module, every company, and every individual hacker has a favorite way of putting the same pins in a row.

We have an entire drawer full of adapters that just go from one pinout to another, or one programmer to many different target boards. We’ll be the first to admit that it’s often our own darn fault — we decided to swap the reset and ground lines because it was convenient for one design, and now we have two adapters. But imagine a world where there was only a handful of distinct pinouts — that drawer would be only half full and many projects would simply snap together. “You may say I’m a dreamer…”

This article is about connectors and standards. We’ll try not to whine and complain, although we will editorialize. We’re going to work through some of the design tradeoffs and requirements, and maybe you’ll even find that there’s already a standard pinout that’s “close enough” for your next project. And if you’ve got a frequently used pinout or use case that we’ve missed, we encourage you to share the connector pinouts in the comments, along with its pros and cons. Let’s see if we can’t make sense of this mess.

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Smart Sutures

Researchers at Tufts University are experimenting with smart thread sutures that could provide electronic feedback to recovering patients. The paper, entitled “A toolkit of thread-based microfluidics, sensors, and electronics for 3D tissue embedding for medical diagnosis”, is fairly academic, but does describe how threads can work as pH sensors, strain gauges, blood sugar monitors, temperature monitors, and more.

Conductive thread is nothing new but usually thought of as part of a smart garment. In this case, the threads close up wounds and are thus directly in the patient’s body. In many cases, the threads talked to an XBee LilyPad or a Bluetooth Low Energy module so that an ordinary cell phone can collect the data.

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Hackaday Prize Entry: A Good Electronics Learning Toolkit

The Maker movement is a wildly popular thing, even if we can’t define what it is. The push towards STEM education is absolutely, without a doubt, completely unlike a generation of brogrammers getting a CS degree because of the money. This means there’s a market for kits to get kids interested in electronics, and there are certainly a lot of options. Most of these ‘electronic learning platforms’ don’t actually look that good, and the pedagogical usefulness is very questionable. Evive is not one of these toolkits. It looks good, and might be actually useful.

The heart of the Evive is basically an Arduino Mega, with the handy dandy Arduino shield compatibility that comes with that. Not all of the Mega pins are available for plugging in Dupont cables, though – a lot of the logic is taken up by breakouts, displays, buttons, and analog inputs. There’s a 1.8″ TFT display in the Evive, an SD card socket, connectors for an XBee, Bluetooth, or WiFi module, motor drivers, a fast DAC, analog inputs, and a plethora of buttons, knobs, and switches. All of this is packed into a compact and seemingly sturdy plastic case, making the Evive a little more durable than a breadboard and pile of jumper wires.

You can check out a remarkably well produced video for the Evive below.

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In Bed With an Arduino, Fighting Sleep Apnea

Sometimes the journey is as interesting as the destination, and that’s certainly the case with [Marc]’s pursuit of measuring his sleep apnea (PDF, talk slides. Video embedded below.). Sleep apnea involves periods of time when you don’t breathe or breathe shallowly for as long as a few minutes and affects 5-10% of middle-aged men (half that for women.) [Marc]’s efforts are still a work-in-progress but along the way he’s tried a multitude of things, all involving different technology and bugs to work out. It’s surprising how many ways there are to monitor breathing.

Debugging the Eeonyx conductive fabric approach
Debugging the Eeonyx conductive fabric approach

His attempts started out using a MobSenDat Kit, which includes an Arduino compatible board, and an accelerometer to see just what his sleeping positions were. That was followed by measuring blood O2 saturation using a cheap SPO2 sensor that didn’t work out, and one with Bluetooth that did work but gave results as a graph and not raw data.

Next came measuring breathing by detecting airflow from his nose using a Wind Sensor, but the tubes for getting the “wind” from his nose to the sensor were problematic, though the approach was workable. In parallel with the Wind Sensor he also tried the Zeo bedside sleep manager which involves wearing a headband that uses electrical signals from your brain to tell you what sleep state you’re in. He particularly liked this one as it gave access to the data and even offered some code.

And his last approach we know of was to monitor breathing by putting some form of band around his chest/belly to measure expansion and contraction. He tried a few bands and an Eeonyx conductive textile/yarn turned out to be the best. He did run into noise issues with the Xbee, as well as voltage regulator problems, and a diode that had to be bypassed.

But while [Marc]’s list of approaches to monitor sleep is long, he hasn’t exhausted all approaches. For example there’s monitoring a baby using lasers to detect whether or not the child is still breathing.

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Wireless Robotic Gripper With Haptic Feedback

We’re not sure what kind of, “High School,” [Sam Baumgarten] and [Graham Hughes] go to that gave them the tools to execute their robotic gripper so well. We do know that it was not like ours. Apparently some high schools have SLS 3D printers and Solidworks. Rather than a grumpy shop teacher with three fingers who, despite that, kept taking the safety off the table saws and taught drafting on boards with so many phalluses and names carved into the linoleum, half the challenge was not transferring them to the line work.

Our bitterness aside, [Sam] and [Graham] built a pretty dang impressive robotic gripper. In fact, after stalking [Sam]’s linkedin to figure out if he was the teacher or the student, (student) we decided they’re bright enough they could probably have built it out of scraps in a cave. Just like [HomoFaciens], and Ironman.

The gripper itself is three large hobby servos joined to the fingers with a linkage, all 3D printed. The mechanical fingers have force sensors at the contact points and the control glove has tiny vibrating motors at the fingertips. When the force of the grip goes up the motors vibrate more strongly, providing useful feedback. In the video below you can see them performing quite a bunch of fairly fine motor skills with the gripper.

The gripper is mounted on a pole with some abrasive tape, the kind found on skateboard decks. At the back of the pole, the electronics and batteries live inside a project box. This provides a counterbalance to the weight of the hand.

The control glove has flexible resistors on the backs of the fingers. The signal from these are processed by an Arduino which transmits to its  partner arduino in the gipper via an Xbee module.

[Sam] and [Graham] did a great job. They worked through all the design stages seen in professional work today. Starting with a napkin sketch they moved onto digital prototyping and finally ended up with an assembly that worked as planned. A video after the break explaining how it works along with a demo video.

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The Foghorn Requiem

Foghorns have been a part of maritime history since the 19th century, providing much needed safety during inclement weather to mariners out at sea. Over time, their relevance has slowly reduced, with advanced navigational aids taking over the task of keeping ships and sailors safe.

The sounds of the foghorns are slowly dying out. Artists [Joshua Portway] and [Lise Autogena] put together the Foghorn Requiem, a project which culminated on June 22nd 2013, with an armada of more than 50 ships gathered on the North Sea to perform an ambitious musical score, marking the disappearance of the sound of the foghorn from the UK’s coastal landscape.

ship_layoutUp close, a foghorn is loud enough to knock you off your shoes. But over a distance, its sound takes on a soulful, melancholy quality, shaped by the terrain that it passes over. The artists tried capturing this quality of the foghorn, with help from composer [Orlando Gough] who created a special score for the performance. It brought together three Brass Bands – the Felling Band, the Westoe Band and the NASUWT Riverside Band, almost 50 ships at sea and the Souter Lighthouse Foghorn to play the score.

Each of the more than 50 vessels were outfitted with a custom built, tunable foghorn, actuated by a controller box consisting of a TI Launchpad with GPS, RTC, Xbee radio and relay modules. Because of the great distances between the ships and the audience on land, the devices needed to compensate for their relative position and adjust the time that they play the foghorn to offset for travel time of the sound. Each controller had its specific score saved on on-board storage, with all controllers synchronized to a common real time clock.

Marine radios were used to communicate with all the ships, informing them when to turn on the controllers, about 10 minutes from the start of the performance. Each device then used its GPS position to calculate its distance from the pre-programmed audience location, and computed how many seconds ahead it had to play its horn for the sound to be heard in time on the shore. The controllers then waited for a pre-programmed time to start playing their individual foghorn notes. The cool thing about the idea was that no communication was required – it was all based on time. Check out the video of the making of the Foghorn Requiem after the break, and here’s a link to the audio track of the final performance.

This is a slightly different approach compared to the Super Massive Musical Instrument that we posted about earlier.

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