Faulty ESP8266s Release Smoke, Then Keep Working?

[Ray] is in a bit of a pickle. All appeared well when he began selling an ESP8266-based product, but shortly thereafter some of them got hot and let the smoke out. Not to worry, he recommends ignoring the problem since once the faulty components have vaporized the device will be fine.

The symptom lies in the onboard red power indicator LED smoking. (Probably) nothing is wrong with the LED, because upon testing the batch he discovered its current limiting resistor is sometimes a little bit low to spec. Off by a hair of, oh, call it an even 1000x.

HAD - HotESPY3Yep, the 4700 ohm resistor is sometimes replaced with a 4.7 ohm. Right across the power rail. That poor little LED is trying to dissipate half a watt on a pinhead. Like a sparrow trying to slow a sledgehammer, it does not end well. Try not to be too critical, pick ‘n place machines have rough days now and then too and everyone knows those reels look practically the same!

The good news is that the LED and resistor begin a thermal race and whoever wins escapes in the breeze. Soon as the connection cuts the heat issue disappears and power draw drops back to normal. Everything is fine unless you needed that indicator light. Behold – there are not many repairs you can make with zero tools, zero effort, and only a few seconds of your time.

[Ray] also recommends measuring and desoldering the resistor or LED if you are one of the unlucky few, or, if worst comes to worst, he has of course offered to replace the product too. He did his best to buy from authentic vendors and apologizes to the few customers affected. As far as he knows no one else has had this problem yet so he wanted to share it with the community here on Hackaday as soon as possible. Keep an eye out.

If you have never seen smoke ISO9001-certified electronics repair before, there is a short video of this particular disaster upgrade caught live on tape after the break.

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RGB LED Matrices With The STM32 and DMA

A few years ago, [Frans-Willem] bought a few RGB LED panels. Ten 32×16 panels is a lot of LEDs, and to drive all of these panels requires some sufficiently powerful hardware. He tried working with an FPGA development board, but that didn’t have enough memory for 24-bit color. The microcontroller du jour – a TI Stellaris – couldn’t get more than 16 bits of color without flickering. With a bunch of LEDs but no way to drive them, [Frans-Willem] put the panels in a box somewhere, waiting for the day they could be used to their fullest capacity.

This day came when [Frans-Willem] was introduced to the STM32 series of chips with the F1 Discovery board. While looking for some electronic playthings to use with this board, he stumbled upon the LED panels and gave them one more try. The results are spectacular, with 33 bits of color, with animations streamed over a router over WiFi.

The panels in question are HUB75 LED panels. In the 32×8 panels, there are six data pins – two each for each color – four row select pins, and three control pins. The row select pins select which row of pixels is active at any one time. Cycle through them fast enough, and it will seem like they’re all on at once. The control pins work pretty much like the control pins of a shift register, with the data pins filling in the obvious role.

The code that actually drives the LEDs all happens on an STM32F4 with the help of DMA and FSMC, or the Flexible Static Memory Controller found on the chip. This peripheral takes care of the control lines found in memory, so when you toggle the write strobe the chip will dump whatever is on the data lines to a specific address in memory. It’s a great way to take care of generating a clock signal.

For sending pixels to this display driver, [Frans-Willem] is using the ever-popular TP-Link WR703N. He had originally planned to send all the pixel data over the USB port, but there was too much overhead, a USB 1.1 isn’t fast enough. That was fixed by using the UART on the router with a new driver and a recompiled version of OpenWRT.

All the software to replicate this project is available on Github, and there’s a great video showing what the completed project can do. You can check that out below.

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3D Printable LED Diffusors

While you can get an LED matrix in any size or shape, the really cool looking ones that are perfect for low-res displays all have diffusors. When they come from a nameless Chinese factory, these diffusors are thin sheets of plastic set into an extruded plastic frame. Since [Jan] has a 3D printer, he figured a custom diffusor was just a few bits of filament and a SCAD file away.

The basis for this custom LED diffusor was a LoL Shield given to [Jan] by the creator at the recent 31C3 conference. This shield is really only just 126 LEDs, multiplexed and in an Arduino form factor, and that many LEDs were just too bright and indistinct next to each other. The plan for a 3D printed diffusor was hatched.

After taking a few measurements, a pair of OpenSCAD files were whipped up and printed out. Assembly consisted of pressing 126 tiny little white diffusors into a frame, but once everything was attached to the matrix, the results were worth it.

Check out the video below for the before and after, demonstrating what a few bits of plastic can do to a LED matrix.

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Ambilight for your Piano (Hero)

That old upright piano still sounds great, and now it can easily have its own special effects. [DangerousTim] added LED strips which change color when he tickles the ivories. The strips are applied along the perimeter of the rear side of the upright causing the light to reflect off of the wall behind the instrument. This is a familiar orientation which is often seen in ambilight clone builds and will surely give you the thrill of Guitar Hero’s brightly changing graphics while you rock the [Jerry Lee Lewis].

Key to this build is the electret microphone and opamp which feed an Arduino. This allows the sound from the piano to be processed in order to affect the color and intensity of the LED strips. These are not addressable, but use a transistor to switch power to the three colors of all pixels simultaneously.

We think there’s room for some clever derivative builds, but we’re still scratching our heads as to how we’d use addressable pixels. Does anyone know a relatively easy way to take the mic input and reliably establish which keys are being played? If so, we can’t wait to see your ambilight-piano-clone build. Don’t forget to tip us off when you finish the hack!

WiFi Lamp Challenge – 5 Hour Speedrun

“We want to get this done quick, not right.”

[CNLohr]’s favorite desk lamp broke, so he gave himself a challenge: convert the lamp to LED and control it via WiFi within 5 hours, from scratch. He video recorded and narrated the whole process and did a nice job of explaining the tricky parts and failures along the way, fast forwarding us through the slow parts.

Some bits and pieces were simple and obvious: gut the old bulb, wire some LEDs, add a few power resistors, toss in a power supply from “like a monitor or something, don’t care” for the LEDs, add in what looks like an LM2596 adjustable power supply for the logic, some kind of ATMega, that new ESP8266 (Wi07C), splice on a power cord, etc. Standard stuff.

To our readers who’s hacks tend to start with soldering irons and screwdrivers, the video shows harder parts of designing an electronics project: creating the PCB in software (he used KiCad), lithographically transferring the circuit to a PCB, bismuth solderpasting & populating the board, and writing and documenting his code on Github. Perhaps most reassuringly, he also showed the consequences of every greedy shortcut and the process of troubleshooting around them.

If you have ever tried to follow a recipe from a cooking show and noticed how easy it all seems when everything is measured and prepped beforehand – and then what a disaster it is when you try it – the same is revealed here. Overall, it is a very thorough demonstration of what it actually takes to design a project – not just perfect circuits and perfect steps to follow.

In the end he got it done in the nick of time an hour late because he cannot add. Close enough.

Thanks [gokkor] for the tip.

World’s First Smart Snowboard Changes Music According To Your Actions

Ever wanted a soundtrack to your life? For a couple of minutes at a time, Signal Snowboards creates that experience with a smart snowboard that varies your music depending on the tricks you perform on your way down the mountain.

The sign on the door says “School For Gifted Hackers”. Inside [Matt Davis] helped interface audio with an accelerometer – something he regularly does with all manner of hacked devices. At first the prototype was an iPhone mimicking the motions of a snowboarder the way fighter pilots describe dogfights with their hands. The audio engine that pulls those mostions to sound is open source and anyone is welcome to do their own tuning.

Once the audio was figured out the boys took it back to their shop and embedded the sensors into a new snowboard. The board is equipped with GPS, an accelerometer, a few rows of LEDs and a bluetooth board to connect to the phone app. It’s all powered by an on-board LiPo battery and a barrel jack out the side to charge it. Channels were cut by hand with a router then electronics sealed in place with epoxy. Not wanting to “just strap some Christmas lights onto a snowboard” the lighting is also connected to the sensors and is programmable.

See the video below of them making the board and taking it out for a test run on Bear Mountain.

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FPGA Ambilight Clone Packs a Ton of Features

[Stephen] designed a standalone Ambilight clone built around an FPGA and recently added many new features to make his design even better. His original design was based around a Spartan 3-E FPGA, but his new design uses the Papilio One board with a Spartan-6 LX9 FPGA. This gives him dedicated DSP hardware and more RAM, allowing him to add more processing-intensive features.

[Steven]’s new board can drive up to 4096 LEDs total, and each LED is colored from one of 256 segmented screen areas. The output of the LEDs is smoothed over a configurable time period which makes the result a bit more pleasant. [Steven] also added color correction matrices and gamma correction tables to make up for differences in LED coloration and so the output can be fine-tuned to the color of the wall behind the TV.

Finally, [Steven] added multiple configurations which can be stored in Flash memory. The FPGA can detect letterboxes and pillarboxes in the video stream and change to a corresponding configuration automatically, so settings rarely need to be manually adjusted. He also added an extensive serial interface to configure all of the parameters and configurations in Flash. Be sure to check out the video after the break to see his setup in action.

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