For a new project I thought I'd like to do some RGB LED stuff. And I got the idea of making a small circuit (small enough to be put inside a ping-pong ball) that controlled one (or more) RGB LEDs from its physical orientation. Simply put, acceleration on the X, Y and Z axes would translate to intensity of the red, green and blue LED. And since there is always an acceleration of 1G towards the center of the Earth (also known as "gravity"), the color of the RGB LED would depend on its orientation.
So the system will comprise the following "blocks":
- 3 axis accelerometer
- LED driver. Or maybe the LEDs can be controlled directly from the MCU.
- RGB LED. One or two.
When looking for parts there's a few things to keep in mind:
- Size matters. It must be as small as possible. I only recently started working with SMD components but already I can't imagine having to deal with those clunky, Soviet tractor-like through-hole components. But I still haven't gone all the way into reflow soldering. So I'm looking for primarily SOIC, TSSOP and TQFP packages. QFN packages are actually possible to hand-solder but it's not fun at all and LGA and BGA are pretty much impossible. For many-pin devices, SOIC is actually kinda big with their huge 1.27 mm pitch and 0.5 mm pitch TSSOP would be preferable.
- Power. As little as possible. I plan on running everything off a single 3V coin cell so voltage should be 2.7 to 3 volts and amps should be as few as at all possible.
- Availability. I much prefer to be able to get everything from one, local provider.
So off to the intertubes for some Googling…