DIY Ambilight – part 3

Finally the new LED strip arrived so now I had al the pieces to connect everything together.

I started by cutting the LED strip to the desired length. I had a total of 96 LEDs so I cut it in pieces of 8, 21, 38, 21, and 8 LEDs. In Hyperion it looked like this:

The next step was to put the strips on the back of the TV and solder them together again. Note: check for the arrow on every section so it points in the same direction. It doesn’t matter if its clockwise or counter clockwise because you can change this in Hyperion.

Now connect all the other pieces. Is used a 4-port USB hub to power the PI and the HDMI splitter and converter. The hub is connected to a USB port of the TV.

Unfortunately the video grabber I used didn’t work. When I tried to take a grabber screenshot I got an error: VIDIOC_S_STD ERROR 25, Inappropriate ioctl for device. Hmm…

A quick search learned my that the chipset of the grabber wasn’t supported. So I ordered another grabber based on a link I found. Different chipset but the same error. This time I got a version 2 grabber and in the link they used a version 1 grabber… So I ordered a third grabber. So now I’m waiting for that to arrive… TBC


DIY Ambilight – part 2

A while back I started with an Ambilight project based on a Raspberry PI and Hyperion. All the parts were delivered so I could finish the installation. The last part was to cut the LED strip into 5 pieces and solder them back together so they could be mounted on the TV.

The moment of truth… Failure! The last part of the strip (the last 7 LEDs) were all white so I thought something was wrong with the soldering. I removed the last part and tried again. Nothing! Now not one LED lit up…

So back to the shed… After a while and trying shorter pieces of LED strip I still didn’t have a working solution. The logging of the software (Hyperion) however looked ok. I saw the software start and also changes in the color of the LEDs was visible in the log. So I started to suspect the PI.

I installed Raspbian instead of Openelec to be able to use some troubleshooting tools. I used gpiotest (based on this article) and things didn’t look good:

It looked like I fried the gpio pins 🙁

One possible reason for this is that I accidentally put 5V on one of the used pins.  These are 3.3 volt logic pins. A voltage near 3.3 V is interpreted as a logic one while a voltage near zero volts is a logic zero. A GPIO pin should never be connected to a voltage source greater than 3.3V or less than 0V, as prompt damage to the chip may occur as the input pin substrate diodes conduct.

So I ordered a new PI and did the test again. This looked a lot better:

So I got a working PI again. Now I have to wait for a new LED strip 🙂

To be continued…