LED Serial Strip v1.0

LED Serial Strips v1.0

They’re in! I’ve finally gotten back the first factory run of serial LED strips and they look awesome. 50 meters of LEDs on a string and I’m really quite happy with them. I’ve tested about half of the batch and so far haven’t run into any build-quality problems. They just seem to all work.

In particular I’ve been impressed with how flexible the strips have been and how resilient (so far) they’ve been in the face of bending. Most LED strips that are available on the market now are coated with a rubbery like clear flexible coating which protects them from the elements and gives them additional strength. The factory was able to apply such a coating but I opted out of it since my intended application was indoors-only and I didn’t want the additional bulk. Also having them uncoated lets me change the color of the LED’s later if I need to. Thus without the coating these strips are significantly more fragile than your typical LED strip and yet they’ve put up with all the punishment I’ve dished out to them so far.

I actually didn’t receive these till about a week and a half or so before Maker Faire 2009, leaving me little time to put together any sort of serious demonstration since I was focused on making sure the 4-spoke monkeylectric wheel was running solid. However I brought them to the Faire anyways and at the very last second put together a primitive demo by stringing a couple 5-meter rolls around our tent with zipties and packing tape and driving them with an Arduino. I thought it all looked really gimpy but I got some nice comments on them anyways.

A surprising number of people asked me if I were was selling the the strips or if I was planning to. You know, that’s one of those interesting questions that the more people ask it, the more I’m inclined to say yes.

LED Serial Strip Driver Shield

Someone else asked me how I was driving the strips. For the demo, I hacked together a simple controller using an Arduino with a Proto Shield.

As far as how you drive the strips (asked by a commenter in a different post), here’s what you need.

   Pin 1 = V+ (4 to 7 volts)
   Pin 2 = LATCH
   Pin 3 = CLK
   Pin 4 = DATA
   Pin 5 = V-

LATCH, CLK, and DATA are used just as with a typical shift register. DATA gets latched into the shift register on the rising edge of CLK but the state of the shift register doesn’t affect the LED output pins until LATCH is driven high. Thus if you tie LATCH high all the time (as I do for the chasing-LEDs effect), then on every rising CLK edge the whole chain of LED’s will shift down by one. If you want to have more control, you can keep LATCH low and clock in a whole chain’s worth of new data before driving LATCH high again. Do this fast enough and you can give the illusion that you’re controlling the LEDs individually.

6 responses to “LED Serial Strip v1.0”

  1. Sparks McGhee says:

    :O Awsome!

    So your deign lets you cut the PCB between the boards or leave them attached for a longer strip right?

    Was your entire order red?

  2. xander says:

    Yup, you can cut the strip every 8 LED’s, or attach more strips to extend it.

    The entire order is red but the strips are uncoated so I can change the colors if I need to.

  3. Ian says:

    Looks awesome. Some of the videos on youtube that show the monkeylectric setup @ maker faire show them blinking in the background – pretty cool!

  4. Garrett says:

    Who are you using for a flex PCBA house? These looked really good at the Maker Faire. I have an idea for an RGB 12-bit per color version. 🙂

  5. xander says:

    I had these made by Signcomplex. I’d be curious to know more about your 12bpp color version!

  6. rcblob says:

    This is exactly the sort of thing i’m working on at the moment. I found some cool ICs (max6974) which can control 8 rgb leds with 12bit pwm per chanel per led 🙂
    Out of curiosity, how much did the factory run cost?

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