After weeks of work we finally finished Electric Wasp. We’re pretty happy with it.
First run
Audio response at event
There are 2008 LPD8806 pixels driven by 2 Teensy 3.1s
First run
Audio response at event
Very cool!
Any tips or lessons learned?
How hard is it to transport?
It’s a bitch to transport, it’s 2.4x1.2m… Weighs around 80-100kg.
For a teensy 3.1 using multiple runs per strip you NEED 74HCT245 buffer chips between both the signal and clock lines. Otherwise you get nothing :/. Must be something to do with software SPI inside the teensy, I don’t have an oscilloscope to probe it.
I had 100-ohm series resistors between each line but sometimes that resistor value was slightly too high I found on runs where there was a bit of a distance between the start of the strip and the chip. Shit started getting weird until I dropped it to 50ohm. No idea why that was the case.
NEVER plug directly into the teensy for fear of ripping out the usb socket when the project is completed… oops.
We had a weird issue where the ground line fried on the board, and blew up a teensy that wasn’t even plugged in. This was when I wired the two power supply grounds together. I didn’t think this would be a problem but it happened twice, still not sure why. Never happened after I separated them.
Running white you need to inject power every ~250px before voltage drop becomes an issue, I did this anyway, but solved this problem by not running white.
I refuse to do any projects without diffusion light now, smooth pixels looks soooooo much better. We used 2mm thick stuff with a gap of around 25mm between the strips and the diffusion layer.
Infinity mirrors look cool. Don’t use transparent silicon when setting them in because of light diffraction inside the silicon.
I should have taken a video showing off the full DMX control, oh well, maybe later.
Better video I think of some the sine wave function.
You need the level shifters because the lpd8806 wants 5v signals and the teensy is putting out 3.3v signals (which really peak at around 3.1v and quickly settle into 2.9v). The apa102 seems a bit more resilient on that front, but I haven’t tried long cable runs with it, yet.
Cool, I realise that but I have never needed the level shifters when plugging directly into the teensy and using pins 11 and 13. Just when I specify the pins I need I had to put them in…
I’ve gotten reports of some people needing shifters on some pins and not others (hardware spi or not). Personally I’ve gotten into the habit of using shifters with ws2812’s with any wire length and with spi based chipsets with anything longer than a foot or two.
Good to know, I’ll just get some PCBs made with the chips and teensy’s all wired up so I can just plug and play from now on I think anyway.
2k pixels, I like you.
What are you using for diffuser?
It’s light diffusing acrylic. The stuff we got is opal coloured perspex.