ATTannenbaum

attiny

It’s that special time of year again where the smell of baking cookies fill the house and shopping mall parking lots are filled with idiots and very angry people. [Kevin] thought it would be a good idea to build an LED Christmas tree and ended up building a great looking tree that’s also very simple.

In the video, the imgur album, and the github, [Kevin] shows us the simplest way to make a color-changing LED Christmas tree. The circuit uses LEDs to drop the voltage and to provide a nice glow around the base of the tree. After that, it’s just an ATtiny13 and some LEDs in a very nice freeform circuit.

Of course, if LED Christmas trees aren’t your thing, [hb94] over on reddit created an LED menorah. Pretty nifty he used an 8-position DIP switch for the circuit. Let’s just hope someone gave him a soldering iron for the last night of Hanukkah.

Driving A WS2811 RGB LED Pixel

[Alan] has been working on driving this WS2811 LED module with an AVR microcontroller. It may look like a standard six-pin RGB LED but it actually contains both an LED module and a microcontroller to drive it. This makes it a very intriguing part. It’s not entirely simple to send commands to the module as the timing must be very precise. But once the communication has happened, the LED will remain the same color and intensity until you tell it otherwise. You can buy them attached to flexible strips, which can be cut down to as few as one module per segment. The one thing we haven’t figure out from our short look at the hardware is how each pixel is addressed. We think the color value cascades down the data line as new values are introduced, but we could be wrong. Feel free to discuss that in the comments.

The project focuses on whether or not it’s even possible to drive one of these pixels with a 16MHz AVR chip. They use single-wire communications at 800 kHz and this really puts a lot of demand on the microcontroller. He does manage to pull it off, but it requires careful crafting in assembly to achieve his timing constraints. You can see a quick clip of the LEDs fading between colors after the break.

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Kick Off The Christmas Decorating With A Review Of 3 Types Of LED Strings

[Todd Harrison] has been on a quest to replace his incandescent Christmas lights with less power hungry LED lights. There are plenty of options out there, but so far he hasn’t found any have the appearance he’s looking for. Since last year he bought three different kinds to try out and has posted a review of each.

Check out the strand of Brite Star Symphony Lights he’s showing off above. There is a white ‘Try Me’ button that lights up the string while still in the package! This offers fifteen bulbs each twelve inches apart. The strand draws 8.4 Watts when in use, you can connect up to 30 strands in series, and they are RGB lights with several different blinking patterns. He spends nearly an hour on this strand in his video review.

Next on his list is a set of Brite Star Classic Style C7 lights. They are single color and are meant to look like traditional large-bulb incandescent strands. At 2.4 Watts per strand you can string together 87 sets of them. This video is much more concise at around twenty-five minutes.

Finally he looks at the Brite Star 50 Mini LED strings. These are the traditional white Christmas tree lights, except in LED. One bulb every four inches on the string adds up to a 2.4 Watt power draw. You can string 58 sets together for a 1000 foot long string. [Todd] spends less than eight minutes reviewing this set.

You can see an intro video after the break but the full reviews are linked in his article. He really liked the Symphony Lights but the other strands have some issues. He discusses what he sees as design flaws in those strands and has decided they’re not really usable because of flickering.

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Optimizing Your Electronics Projects With A Camera

What do you do when you have a microcontroller you’re trying to optimize? One method is using a debugger, but for AVRs and such that’s not a very common technique. For lower-level electronics projects, it’s nearly impossible, even. [Cnlohr] built a small Minecraft server that listens to in-game redstone circuits, but the performance of his real-world to block-world bridge wasn’t what he hoped. He came up with a pretty clever way of figuring out what was slowing his server down without any special gear at all.

[cnlohr]’s Minecraft server is just a simple AVR microcontroller, Ethernet adapter, and SD card affixed to a beautiful glass PCB. The performance of his server wasn’t what he expected; downloading a largish file from the server resulted in a download rate of about 55kbps, much slower than he expected. He wasn’t quite sure what the hangup was, so he took a camera and with a long exposure time took a very blurry picture.

The Minecraft server has a blue LED to show when the SD card was being accessed. In the picture above, [cnlohr] saw that SD card access was taking far too long, and if he wanted to optimize the code this would be the place to start.

Not bad for a dead-simple method of seeing where the code on your microcontroller project is slowing down.

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One Dimensional PONG, Take Two

Needing a Christmas present for his 4- and 5-year-old nieces, [John] built a one-dimensional PONG game, sure to be the delight of rosy-cheeked children on a Christmas morn.

The new and improved 1D PONG game is built around a digital RGB LED strip with an LPD8806 LED controller. The speed of the ‘ball’ is controlled by a pot on one side of the game. With each player pressing their button at the right time, the ball bounces back to the other player. Missing the ball awards a point to the other team and most likely an increase in the player’s frustration, greatly increasing the risk of this game being thrown across the room.

While it’s not an obscenely long 1D PONG game like [Jason]’s previous 5 meter version, it’s more than enough to keep a pair of kids occupied for more than a few minutes, a remarkable achievement for just a microcontroller, buttons, and a piece of LED strip.

You can get [John]’s AVR code in this pastebin or just check out the video after the break.

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Roomba And Virtual Walls Make Up This Theme Family Halloween Costume

It figures. You spend a ton of time making a cool set of costumes and then you can’t get your kid to pose for a picture. It’s okay though, we still get the point. This themed set of costumes dresses the little one as a Roomba vacuuming robot while mom and dad are suited up as virtual walls (modules that are used to keep the bot from falling down stairs, etc.). It’s fun and unique, but had it not been for some additional electronics this would have been relegated to a links post. For safety sake each costume was outfitted with a ring of LEDs. As a challenge, the lights were given the ability to sync up patterns with each other.

Each costume has a circular frame at the top with a set of RGB LED strings attached. To get them to display synchronized patterns an IR transmitter/receiver board was designed and ordered from OSHPark. Each costume has four of these modules so no matter where the wearers are facing it should not break communications. A demo of the synchronized light rings can be seen after the break

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Wireless Water Heater Monitor Uses Whatever Was Lying Around

[Chris] set out to build a monitoring system for his water heater. It doesn’t Tweet or send SMS messages. It simply lights up an LED when the water heater is active. The one thing that complicates the setup is that he didn’t want to pull any wire from the garage into the house. What you see above is the wireless setup he used to accomplish this goal.

This is an electric water heater, so [Chris] patched into the 230V heating element feed. When the water heater is idle this connection is cut off. He used a transformer to step the voltage down to 17V and rectified it before feeding a 7805 power regulator. The rest of the transmitter circuit consists of a 555 timer driving the coil seen on the left. It is made out of telephone wire, with each of the four conductors inside connected together to multiply the number of windings. The box of breakfast sausages hosts the receiver coil. His hardware takes the induced current from that coil and amplifies it, feeding the signal to the base of a transistor responsible for switching the status LED. This works through the 6″ thick garage wall, although he did have to use a battery on the receiving end as his wall wart was injecting way too much noise into the system to work.