Re: To build or not to build ...
Well, decided to take this project a step further and actually start collecting parts. However, I've ditched my original design and have decided to do individual control of the LED strips via I2C.
This means that:
I only have to run 4 wires to the digits, power and data.
Each digit can just be daisychained - so only 4 wires back to my uC
No multiplexing, so I gain a heap more brightness and can also drop the 2nd MCU off my design.
I was forced to learn Altium
I decided to use the common WS2801 LED driver chip, with 3 MOSFET's for driving my LED strips. I decided to design them so that they'd solder right onto the ends of the LED strip.
Because of this, I had to be able to put SMD components on both sides, which Fritzing doesn't yet do. A friend recommended Altium, and after going in circles trying to work out how to use it, I have a board design and off for fabrication in 24 hours
Total board size is only 10x23mm!
Means I can also fit 8 of them on a standard 5x5cm PCB, so I can get 80 boards for only $14 shipped. Downside is I'll have to cut them myself. Opted for a 0.8mm PCB instead of 1.6mm to hopefully make that process a bit easier.
Seeing as I have to assemble close to 80 of these, I also bought a cheap hot air soldering station, some angled tweezers and some solder paste to try my hand at some hot air SMD reflow soldering. This will also be useful for another possibly commercial SMD project/development in the future, so worth the investment.
This is the schematic (The connection to Byp instead of Vout on the vreg is a simple pinout fix)
This is a far superior way to my previous design, and ends up a little cheaper also.
Comparison to a AAA battery & how it'll mount on the strip:
If anyone is interested in these little boards, I can probably release the source/design, or even do kits if there is any interest.
On the same note, the laser cutter is coming along nicely and should be able to cut out the digits for this clock project out of styrofoam for a nice look.
Dan
