ShiftBrites in stock now.
ShiftBrite is a simple device I am designing and producing. It allows easy control of a bright RGB LED. The interface is a straightforward clocked serial data line and a latch input. All signals are buffered and passed through for good performance over long cables and daisy chaining many devices. Many ShiftBrite devices can be controlled from any type of controller that supports clocked serial data output, which is practically all microcontrollers and even PC parallel port or FTDI bitbang adapters.
The controller IC is an A6281 from Allegro. This actually does all the necessary work to control three LED channels. It receives clocked serial data, generates regulated power for its internal logic, performs a 10-bit PWM cycle for each channel, provides current control up to 150ma per channel, and allows dot correction for improving the match between LEDs used together. It buffers the input signals and passes them straight through to the other side of the package. The A6281 is available in a 16-pad 3mm by 3mm package with thermal pad.
LEDs are a bright common-anode RGB part purchased directly from China on eBay. The seller is either TopBright or Shop4LEDs, I believe they are the same company. In large quantities, the pricing is very reasonable; in fact, my Chinese contacts were having difficulty sourcing similar LEDs anywhere near the same prices.
I am having the circuit board produced by OurPCB. They are also sourcing some of the parts and will assemble the complete devices. I won't post the exact pricing here, but if you have an idea for a device and need it produced, try getting a quote from OurPCB. You will likely be impressed at how low the barrier to entry is for mass-producing custom electronics products.
After I have verified the final product, I may be offering these devices for sale. I will most likely be able to price these in the $5.00 range, with discounts for multiple pieces.
I ordered samples of the A6281 from Allegro, and wanted to test the chips to make sure what I was reading in the datasheet matched reality. I decided to dead-bug wire the chip to a proto board for testing. The images below show some of this process and the results. This method did work just fine, I was able to successfully control a set of LEDs.
The circuit boards for the prototypes finally arrived, and I assembled some ShiftBrites. The common-anode LEDs from TopBright, I discovered, have an incorrect wiring diagram. The common anode lead is actually to the right of the notch, not below it. Fortunately this only means rotating the LED 180 degrees. The last photo below shows a second ShiftBrite chained to the previous one on a breadboard.
Submitted by Garrett on Sun, 03/09/2008 - 00:50.