Saturday, November 30, 2013

Blinky LED earrings

Getting into SMD fabricating has really opened the doors to all sorts of new ideas.

My first attempt at a wearable was sort of inspired in part by FLORA and the other wearable stuff at AdaFruit.

It's a 1 inch diameter board with 8 SMD LEDs mounted equidistantly around the outer edge. Each is hooked up to a digital pin on an ATTiny84. There's also a micro-switch input to the controller and the whole thing is powered by a CR1225 battery. A pair of them would be a pair of earrings.

Here, the purple color of OSH Park's boards is actually a good thing - the hope is that the actual earrings themselves are dark and unobtrusive, or at least as much as they can be. The usual garish green solder mask color would be awful in comparison.

The button will be used to select different blink patterns.

It's asking a lot for a CR1225 to drive even a single LED, so although the board was designed with series resistors for each LED, the initial prototype is going to be stuffed with "0 ohm" parts. The blink patterns are going to be designed so that only a single LED is on at once.

The real question is still going to be whether it's going to work at all. The risk is that pulsing the LED will cause the voltage from the battery to drop enough that it hoses the controller. I don't know what I would do to fix it, though, because there isn't room for something bigger, like a CR2032.

But the larger point here is that with through-hole versions of these components, there's just no way this would be even worthy of consideration.

I got the SMD LEDs in the mail today and broke a couple out to try them with a pair of AA batteries. I probably overdrove them a little, but they were quite bright.

We'll see.

No comments: