arduino porkypine

[mtbf0]

here's myboarduino porkypine.

1 boarduino, 18 100ohm resistors, 6 rgb leds, 6 drinking straws, 18 channels of pwm at about 122Hz. lots of code.

it's really quite beautiful. unfortunately the colors are pretty washed out in the video. maybe i'll try shooting again with a little more ambient light.

there is currently no scripting capability. what you are seeing is commands sent to it over serial from a minicom script.

one has to be careful of bumping one's head on the mega168's current sourcing max. the most you're seeing in the video is 9 channels at 100% duty cycle and nine channels completely off at any one time. last night i had 15 channels at 50% and 2 at 100% and was getting some bizarre flickering. 18 channels at 50% looked ok, though. who knows?

have to play with the resistor values. the greens are super bright, the reds very bright, and the blues much weaker than the other 2 colors. i also figure that increasing the values will give more apparent control over the colors.

and, of course, have to get scripting going.

[cell]

sweet.

[Tcepsa]

Hehe, I love the straws; haven't seen that idea before!

[tendo]

I know I'm resurrecting an ancient thread, but if anyone is subscribed could you tell me about doing this on a massive scale? I'd like to build a gigantic one of these. Thanks!

[Tcepsa]

That sounds like a job for Shift Registers! Do a search for them on Hackaday.com; they recently had a decent tutorial on how to use them and chain them together. I am curious about whether there are other (better?) ways to do it as well...

[tendo]

Awesome, thanks. I'll look into that

[mtbf0]

check out the rainbowduino from seeed studios. 64 rgb leds.

the porkypine was a programming excercise. getting 18 channels of software pwm. i was inspired by the blinkm but couldn't see spending $14 per led. the porkypine in the video is tethered, but the one i use for a nightlight is scriptable. there are parts of the code that i've never tested and i haven't touched it for a good long time. if anyone would like a crack at it let me know.

[tendo]

Awesome. Thanks for the tip!

[mtbf0]

for another board with more complete hardware documentation see the emsl meggy jr.

for something that just drives crazy numbers of leds emsl also has the peggy 2 and peggy 2le.

keep in mind that all of these displays are multiplexed. the duty cycle on the rainbowduino and meggy jr is 1/8. on the peggy boards it's 1/25.

with the porkypine you can turn on all the leds at once, but you'll probably reset the chip and maybe fry it.

[Entropy]

I know I'm resurrecting an ancient thread, but if anyone is subscribed could you tell me about doing this on a massive scale? I'd like to build a gigantic one of these. Thanks!

What sort of arrangement do you want?

Matrix like the Rainbowduino mentioned earlier?

A fixed linear array?

A strand of "christmas light" style nodes that are individually controllable?

As you go from "matrix" to "flexible strand", things get more expensive and difficult as control has to be decentralized.

For a fixed linear array - take a look at the NXP PCA9635 - 16 high speed PWM channels off of an I2C bus. It's REALLY easy to drive from an AVR (I use my Boarduino as a master for testing, and eventually I'll be using the Boarduino as a DMX-to-I2C bridge).

To work with the PCA9635 you'll need a TSSOP-28/SSOP-28 breakout board (such as Sparkfun's for around $4/board, if anyone knows of a cheaper source I'd LOVE it) and a decent temp controlled soldering iron (such as the Aoyue 937 - about $50), along with some solder flux. TSSOP-28s aren't hard to solder if you use lots of flux, I used the "roll a ball of solder across the pins" technique and only had to clean up two solder bridges.