Archive for February, 2013

Update on Ambilight

Posted: February 26, 2013 in Ambilight
Tags: ,

As with all things in electronics the easiest most trivial projects are the ones that give you the most hassle. I have completed the build for my Ambilight system and am using a 3.5A 5V supply which is doing fine for now. Each LED can draw as much as 0.25W on full brightness so I’ll either just use half the LEDs for now or get a bigger power supply. The problem I’ve been having is that I’m getting strange results outputting the communications signal to the LED strip. During initial testing everything was going fine but I was only ever outputting green, red or blue at any given time. Now that I’ve put the whole thing together there seem to be some comms problems. On closer inspection of the WS2811 datasheet I’ve seen that VIH (the input voltage detected as a high) is 0.7VDD which with my 5V supply is 3.5V. The microcontroller I am using uses a 3V3 IO voltage so I can see how when communications get fast things would go wrong. I will try the system tonight with an arduino at 5V IO voltage and see if it fixes the problem.

On a side note Adafruit have updated their Flora Pixel to version 2 which I think uses the same WS2811 IC. As always the have a library on their github page which implements a really nice colour wheel demo. The FastSpi library that I’ve been using has also had an update recently which makes the code a lot cleaner. Have a look but be aware that it is just a preview release at the moment. I’ve uploaded my current working into a project on my github page but this will be cleaned up when I have a final working version. The boblight.conf I was talking about in my last post is there too.