An SLA-Printed Pogo Pin Programming Jig

If you have a microcontroller to program, it can be an easy enough process to hook up a serial lead and perform the task. If however you have hundreds of microcontrollers on PCBs to program, connecting that lead multiple times becomes an impossibility. In manufacturing environments they have pogo pin jigs, an array of spring-loaded pins carrying the programming signals that line up perfectly with the appropriate pads on a PCB places on top of it.

[Conor Patrick] is working on an upgrade to the U2F Zero 2-factor authentication token, and he faces exactly this problem of needing to program a lot of boards. His pogo pin jig is very nicely executed, and he’s taken us through his design and manufacture process for it.

Starting with his PCB design in Eagle, he exported it to Fusion 360 in which he was able to create a jig to fit it. Into the jig model he placed the holes for his chosen pogo pins in the appropriate places, before printing it with an SLA 3D printer. He is particularly complementary about the pins themselves, a solder bucket design that comes from mill-Max, and was sourced via DigiKey.

The proof of the pudding is in the eating, and happily when his completed jig received its first board, everything worked as planned and the programming proceeded flawlessly. We’ve shown you other pogo pin jigs, but this one is particularly nicely executed.

Drill Jig Helps Mount WeMos D1 Mini

As far as ESP8266 boards go, the WeMos D1 Mini is a great choice if you’re looking to get started with hackerdom’s microcontroller du jour. It’s small, well supported, and can be had ridiculously cheap. Often going for as little as $3 USD each, we buy the things in bulk just to have spares on hand. But that’s not to say it’s a perfect board. For one, it lacks the customary mounting holes which would allow you to better integrate it into finished products.

This minor annoyance was enough to spring [Martin Raynsford] into action. He noticed there was some open area on the D1 Mini’s PCB where it seemed he could drill through to add his own mount points, but of course popping holes in a modern PCB can be risky business. There’s not a lot of wiggle room between success and heartbreak, and it’s not like the diminutive D1 Mini is that easy to hold down to begin with. So he designed a laser-cut jig to allow him to rapidly add mounting holes to his D1 Mini’s assembly line style.

For those who might be skeptical, [Martin] reports he’s seen no adverse effects from drilling through the board, though does admit it’s possible the close proximity of the metal screw heads to the ESP8266’s antenna may have a detrimental effect. That said, he’s tested them in his projects out to 25 m (82 feet) with no obvious problems. He’s using a 2 mm drill bit to make his hole, and M2 x 6 mm machine screws to hold the boards down.

The jig design is released as a SVG and DXF for anyone with a laser cutter to replicate, but it shouldn’t be too difficult to extrude those designs in the Z dimension for hackers who haven’t yet jumped on the subtractive manufacturing bandwagon.

When a project makes the leap from prototype to in-house production, designing and building jigs become an essential skill. From flashing firmware to doing final checkout, the time and effort spent building a jig early on will pay for itself quickly in production.

Trials and Tribulations in Sending Data with Wires

When working on a project that needs to send data from place to place the distances involved often dictate the method of sending. Are the two chunks of the system on one PCB? A “vanilla” communication protocol like i2c or SPI is probably fine unless there are more exotic requirements. Are the two components mechanically separated? Do they move around? Do they need to be far apart? Reconfigurable? A trendy answer might be to add Bluetooth Low Energy or WiFi to everything but that obviously comes with a set of costs and drawbacks. What about just using really long wires? [Pat] needed to connect six boards to a central node over distances of several feet and learned a few tricks in the process.

When connecting two nodes together via wires it seems like choosing a protocol and plugging everything in is all that’s required, right? [Pat]’s first set of learnings is about the problems that happen when you try that. It turns out that “long wire” is another way to spell “antenna”, and if you happen to be unlucky enough to catch a passing wave that particular property can fry pins on your micro.

Plus it turns out wires have resistance proportional to their length (who would have though!) so those sharp square clock signals turn into gently rolling hills. Even getting to the point where those rolling hills travel between the two devices requires driving drive the lines harder than the average micro can manage. The solution? A differential pair. Check out the post to learn about one way to do that.

It looks like [Pat] needed to add USB to this witches brew and ended up choosing a pretty strange part from FTDI, the Vinculum II. The VNC2 seemed like a great choice with a rich set of peripherals and two configurable USB Host/Peripheral controllers but it turned out to be a nightmare for development. [Pat]’s writeup of the related troubles is a fun and familiar read. The workaround for an incredible set of undocumented bad behaviors in the SPI peripheral was to add a thick layer of reliability related messaging on top of the physical communication layer. Check out the state machine for a taste, and the original post for a detailed description.

Feeding Dogs over Twitch is Latest E-Sport Craze

The modern social-networking fueled Internet loves two things more than anything: pets, and watching other people do stuff. There’s probably a scroll tucked behind a filing cabinet at Vint Cerf’s house that foretells anyone who can harness these two elements will gain control of the Internet Ready Player One style. If so, we’re thinking [Tyler Pearce] is well on his way to ascending the throne.

In an effort to make the Overwatch Twitch streams of his betrothed even more enticing, [Tyler] came up with a way for viewers to feed their dog Larry by dropping a command in the chat. There’s a surprisingly complex dance of software and hardware to make this reliable and visually appealing, but it’s worth it as showmanship is important in the brave new world of competitive e-sports. We’re assuming that’s what it says in the issue of ESPN Magazine with the Fortnite player on the cover, but nobody at Hackaday would qualify for a subscription to it so we don’t really know for sure.

A server running on the computer provides a slick administrative dashboard for the treat system, including a running log of who fed Larry and when. There’s also a number of checks in place to prevent too many treats being dispensed in a short time period, and to keep an individual from spamming the system.

On the hardware side, he’s using two NodeMCU ESP8266 microcontollers connected to a local MQTT broker: one to handle the lighting and one to run the 3D printed auger that actually pushes the food out. The printed auger is powered by a standard hobby servo, and even includes an IR sensor to automatically stop spinning when it detects a treat has been dispensed. [Tyler] reports the auger works quite well, though does have a tendency to jam up if overfilled.

We’ve seen all manner of automated pet feeders over the years, even ones with their own email accounts. So it was probably only a matter of time until they came to Twitch. If you can install Linux with it, why not use it to feed your dog? Or somebody else’s, as the case may be.

DIY Arduino Soldering Iron Hits Version 2.0

A few months ago we brought word that [Electronoobs] was working on his own open source alternative to pocket-sized temperature controlled soldering irons like the TS100. Powered by the ATMega328p microcontroller and utilizing a 3D printed enclosure, his version could be built for as little as $15 USD depending on where you sourced your parts from. But by his own admission, the design was held back by the quality of the $5 replacement soldering iron tips he designed it around. As the saying goes, you get what you pay for.

But [Electronoobs] is back with the second version of his DIY portable soldering iron, and this time it’s using the vastly superior HAKKO T12 style tip. As this tip has the thermocouple and heating element in series it involved a fairly extensive redesign of the entire project, but in the end it’s worth it. After all, a soldering iron is really only as good as its tip to begin with.

This version of the iron deletes the MAX6675 used in V1, and replaces it with a LM358 operational amplifier to read the thermocouple in the T12 tip. [Electronoobs] then used an external thermocouple to compare the LM358’s output to the actual temperature at the tip. With this data he created a function which will return tip temperature from the analog voltage.

While the physical and electrical elements of the tip changed substantially, a lot of the design is still the same from the first version. In addition to the ATMega328p microcontroller, version 2.0 of the iron still uses the same 128×32 I2C OLED display, MOSFET, and 5V buck converter from the original iron. That said, [Electronoobs] is already considering a third revision that will make the iron even smaller by replacing the MOSFET and buck converter. It might be best to consider this an intermediate step before the DIY iron takes on its final form, which we’re very interested in seeing.

The first version of the DIY Arduino soldering iron garnered quite a bit of attention, so it seems there’s a decent number of you out there who aren’t content with just plunking down the cash for the TS100.

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Voice Controlled Stereo Balance With ESP8266

A stereo setup assumes that the listener is physically located between the speakers, that’s how it can deliver sound equally from both sides. It’s also why the receiver has a “Balance” adjustment, so the listener can virtually move the center point of the audio by changing the relative volume of the speakers. You should set your speaker balance so that your normal sitting location is centered, but of course you might not always be in that same position every time you listen to music or watch something.

[Vije Miller] writes in with his unique solution to the problem of the roving listener. He’s come up with a system that can adjust the volume of his speakers without having to touch the receiver’s setup, in fact, he doesn’t have to touch anything. By leveraging configurable voice control software running on his computer, his little ESP8266-based devices do all the work.

Each speaker has its own device which consists of a NodeMCU ESP8266 and X9C104 digital potentiometer inside of a 3D printed case. The audio terminal block on the gadget allows him to connect it inline between the speaker and the receiver, giving [Vije] the ability to adjust the volume through software. The source code, which he’s posted on the Hackaday.io project page, uses a very simple REST-style API to change speaker volume based on HTTP requests which hit the ESP8266’s IP address.

The second part of the project is a computer running VoiceAttack, which lets [Vije] assign different actions based on what the software hears. When he says the appropriate command, the software goes through and fires off HTTP requests to the nodes in the system. Everything is currently setup for two speakers, but it shouldn’t be too difficult to expand to more speakers (or even rooms) with some adjustment to the software.

It’s not the first voice controlled speaker we’ve ever seen, but it does solve a very specific problem in a unique way. We’d be interested in seeing the next logical step, which would see this technology integrated into the speaker itself.

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Less is More: A Micromatrix Display in a Square Inch

In your living room, the big display is what you want. But in an embedded project, often less is more. We think [bobricius] will agree since he submitted a tiny 4×5 LED display into our square inch challenge. The board features an ATtiny CPU and twenty SMD LEDs in a nice grid. You can see them in action, scrolling to some disco music in the video below.

There is plenty of room left in the CPU for bigger text strings — the flash memory is just over 10% full. A little side-mounted header makes it easy to program the chip if you want to change anything.

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