FPGA Based Ambilight Clone

The Philips Ambilight – a bunch of rear-facing RGB LEDs taped to the back of a TV – is becoming the standard project for anyone beginning to tinker with FPGAs. [DrX]’s is the best one we’ve seen yet, with a single board that reads and HDMI stream, makes blinkey lights go, and outputs the HDMI stream to the TV or monitor.

[DrX] is using an FPGA development board with two HDMI connectors – the Scarab miniSpartan6+ – and a strand of WS2801 individually addressable RGB LEDs for this project. With a bit of level shifting, driving the LEDs was easily taken care of. But what about decoding HDMI?

Most of the project is borrowed from a project that displays a logo in the corner of a 720p video stream. The hardware is the same, but for an Ambilight clone, you need to read the video stream and process it, not just write to it. By carefully keeping track of the R, G, and B values for each pixel along with the pixel clock,  the colors along the edge of a display can be averaged. It’s not as difficult or as memory-intensive as building a frame buffer; nearly all of the picture data is thrown out when assembling the averages around the perimeter of the display. It does work, though.

After figuring out the average color around the perimeter of the display, it’s just a simple matter of driving the LEDs. Tape those LEDs to the back of a TV, and there’s an Ambilight clone, made with an FPGA.

[DrX] has a few videos of his project in action. You can check those out below.

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This Cake is Not a Lie

Introducing the world’s first(?) edible and interactive RGB matrix cake — the ArCake.

[Treibair], one of our readers from Germany was inspired a few years ago with the LED cake we made here at Hackaday. Ours used angel food cake squares that allowed LED lights to shine through the squares from underneath the cake, where the LEDs are housed in the technologically advanced cake tray. It worked pretty well but we didn’t exactly recommend people to follow in our foodsteps.

That didn’t stop [Treibair] though, and he came up with his own unique twist on the cake! Instead of bothering with various cubes of angel food cake, he had a much more direct method.

It’s easy to do, just follow these steps:

  • Drill some holes in a cake
  • Put your jello in that cake
  • Make her open the box

And that’s the way you do it.

The resultant LED diffusers let lots of light through, while retaining their most important quality — tastiness. All in all, he made 30 jello filled holes which allowed him to place a 5 x 6 LED matrix underneath the cake. Now when he gives the cake to his wife, it will read her a Happy Birthday message, and then allow her to play a Jump’n’Run game using a Wii nunchuck controller!

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A Wooden LED Matrix Coffee Table

[johannes] writes in with a pretty impressive LED table he built. The table is based around WS2801 serially addressable LEDs which are controlled by a Raspberry Pi. The Pi serves up a node.js-driven web interface developed by [Andrew Munsell] for a room lighting setup. The web interface controls the pattern shown on the display and the animation speed.

[johannes] built a wooden coffee table around the LED matrix, which includes a matte glass top to help diffuse the lighting. An outlet to plug in a laptop and two USB charging ports are panel-mounted on the side of the enclosure, which are a nice touch. The power supply for the LEDs is also inside the enclosure, eliminating the need for an external power brick.

While [johannes] hasn’t written any software of his own yet, he plans on adding music synchronization and visualizations for weather and other data. Check out the video after the break to see the table in action.

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Deck the Halls with a Raspberry Pi Controlled Christmas Tree

You know the holiday season is getting close when the Christmas light projects start rolling in! [Osprey22] is getting a jump on his holiday decorations with his Christmas Tree light show controlled by a Raspberry Pi. Yes, we know he could have done it with an Arduino, or a 555, but the Raspi makes for a convenient platform. With a WiFi module, code changes can be made remotely. The Raspberry Pi’s built-in audio interface also makes it easy to sync music to flashing lights, though we’d probably drop in a higher quality USB audio interface.

[Osprey22’s] Raspberry Pi is running his own custom python sequencer software. It takes an mp3 file and a sequence file as inputs, then runs the entire show. When the music isn’t playing, the Pi loops through a set of pre-defined scenes, changing once per minute.

The hardware itself is pretty straightforward. The Raspberry Pi controls 8 solid state relays through its GPIO interface. 8 strings of lights are more than enough for the average tree. [Osprey22] topped the tree off with a star made of wood and illuminated by a string of 25 WS2801 RGB LED pixels.

Click past the break to see [Osprey22’s] tree in action!

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A Raspi Ambilight With HDMI Input

With the Raspberry Pi now most famously known as a $30 media PC, it only makes sense that the best uses for the GPIO pins on the Pi are used for an Ambilight. [Great Scott Labs] put up a great video on using the Pi as a uniquely configurable Ambilight with Hyperion and just about any video input imaginable.

This isn’t the first Ambilight clone [Great Scott] has put together, but for the first version the Ambilight functioned only under Raspbian and not any random HDMI input. The new version solves this by using an HDMI splitter box, feeding into an HDMI to composite converter, and finally into a USB composite capture dongle attached to the Raspi.

With the software in the instructions, the Raspi effectively mirrors the video coming from the video capture dongle. The Pi is running Hyperion to control a strip of WS2801 RGB LEDs, making the back of any TV glowey and blinkey.

Since [Great Scott] is using a component video signal as an input, the adapters necessary to have any device work with this Ambilight are readily available. We’d honestly like to see this build working with the old Commodore disk access screen border going nuts, so be sure to send that in if you ever get that working.

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Massive LED Display Makes Use of Reused Soda Bottles


What better way to make a giant LED display than out of old empties and bottle crates? This is the Mate Light (pronounced Mah-Tay).

We were first introduced to the ever popular Club-Mate soda at one of the first hackerspaces we visited during our Hackerspacing in Europe Tour. It’s a soft drink produced in Germany, which seems to be the exclusive non-alcoholic drink of choice for almost all hackerspaces in Western Europe. The spaces in the Netherlands and Belgium would even make road trips to Germany just to load up a van with the drink to bring back home. Personally we didn’t really understand what was so special about it, but maybe we just didn’t drink enough!

Anyway, this impressive display makes use of 640 empties arranged in 4 rows of 8 crates for a decent 16 x 40 resolution. Each bottle is wrapped in aluminum foil and contains one RGB LED with a WS2801 driver. Each row of crates is connected to a TI Stellaris Launchpad, which has four hardware SPI interfaces — conveniently the number of rows of crates used! From there, an ancient ThinkPad T22 laptop runs the control program over USB to the microcontroller board. Their first software implementation used a Python script which was painfully slow — they’re now putting the finishing touches on using a C script instead.

Stick around to see the display in all of its awesomeness.

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