I set out to design an affordable and accessible solution for dome lights that any builder can assemble without having to wait for a run. I based the design on the popular Arduino microcontroller but in theory, any microcontroller could be used. Many different configurations are possible, and you can build some or all of the system: The RLD, the FLD, the PSI, or any combination of these. The only restricting feature is that the HP lights are run from the PSI boards.
This solution covers all the typical lights in a dome:
Though Arduino is not the only microcontroller that can drive these lights, it's the one I prototyped with so my desciption here will refer to Arduino.
You can power the setup a couple of different ways:
A key feature of the design is that each board chains to another. For example, you might connect the RLD board to the 3 digital pins on the Arduino (or insert a Pro Mini board; see below), connect the top FLD to the RLD, connect the bottom FLD to the top FLD, connect the front PSI to the bottom FLD, connect the rear PSI to the front PSI. This is just one possible arrangement, and in reality you could connect them in any order you want. Just chain one board to the next.
The connection from one board to another is with a 5-conductor jumper wire with female pin connectors on the ends. You can make these yourself or buy them pre-made from sparkfun.com or eBay . For simplicity, each board has two sets of 5-pin headers, one for "IN" and one for "OUT". These 5 pins supply the 3 digital signals plus 5V DC and ground.
You will need to connect the first board in the chain to 3 digital pins on the Arduino (or use a Pro Mini onboard the RLD). That first board will also need to receive power, either from the Arduino itself or from an external source. From there, you can just chain the power from board to board.
One convenient way to connect a microcontroller is to insert a Pro Mini board in the 24-pin DIP socket on the RLD board. Since the Pro Mini has the same footprint as a 24-DIP IC, it will drop right into a standard socket. If you take this route, you will only need to supply power (either unregulated 6-20 volts or regulated 5 volts) via one of the screw terminals on that board, and all the other connections are already made for you via traces.
If you choose not to use a Pro Mini board, you would just connect your microcontroller of choice to the set of pins marked "IN" on the first board in your chain. The RLD has both the socket for a Pro Mini and the "IN" and "OUT" pins like all the other boards.
Note that if you go with the onboard Pro Mini, your RLD has to be the first board in your chain.
You should prepare your Pro Mini board by soldering 1x12 pin headers onto the BOTTOM of the board. Then you'll be able to insert it into the DIP socket. Also solder a 1x6 pin header onto the TOP of the board for connecting your programming cable. The prepared board should look like this:
Following is a list of parts necessary to assemble a set of droid lights.
| item | each | qty | total | source | part # | Incl shipping? | notes |
|---|---|---|---|---|---|---|---|
| 5-board set | 35.00 | 1 | 35.00 | pcb.laen.org | y | ||
| RLD board x.xx sq. in. | 0.00 | 1 | 0.00 | pcb.laen.org | y | ||
| FLD board x.xx sq. in. | 0.00 | 2 | 0.00 | pcb.laen.org | y | ||
| PSI board 2.76 sq. in. | 0.00 | 2 | 0.00 | pcb.laen.org | y | ||
| LED 3mm | 0.025 | 225 | 5.625 | eBay | y | ||
| LED 5mm | 0.025 | 27 | 0.675 | eBay | y | 6 each R, B, Y and G (for PSI) plus 3 white (for HP) | |
| DIP24 300 mil socket | 0.27 | 5 | 1.35 | Digi-Key | 3M5466-ND | n | these accept the MAX7219CNG chips |
| DIP24 600 mil socket | 0.27 | 1 | 0.27 | Digi-Key | 3M5467-ND | n | this accepts the Arduino Pro Mini |
| MAX7219CNG | 1.00 | 7 | 7.00 | eBay | n | order 1 or 2 extra | |
| cap 10uF | 0.52 | 5 | 1.56 | Digi-Key | 445-2863-ND or 445-2874-ND | n | each board requires one |
| cap 0.1uF | 0.15 | 5 | 0.45 | Digi-Key | 490-5369-ND | n | each board requires one |
| resistor 24k for FLD | 0.06 | 2 | 0.12 | Digi-Key | 24KH-ND | n | |
| resistor 28k for RLD | 0.11 | 1 | 0.11 | Digi-Key | 28.0KXBK-ND | n | |
| resistor 10k for PSI | 0.13 | 2 | 0.26 | Digi-Key | 10.0KXBK-ND | n | |
| screw terminal 100 mil | 0.75 | 1 | 0.75 | Digi-Key | A98333-ND | n | you'll need one of these if you're using the onboard Arduino Pro Mini |
| double row header strip | 0.03 | 5 | 0.09 | eBay | y | sellers typically offer strips of 40+ pins; break off groups of 5 | |
| jumper wire, 5-pin, 4" | 0.95 | 1 | 0.95 | sparkfun.com | PRT-10365 | n | this is to connect the two FLD boards together |
| jumper wire, 5-pin, 12" | 1.95 | 3 | 5.85 | sparkfun.com | PRT-10375 | n | for all other board-to-board connections |
| Arduino Pro Mini - 5V | 18.95 | 1 | 18.95 | sparkfun.com | DEV-09218 | n | |
| FTDI Basic Breakout - 5V | 14.95 | 1 | 14.95 | sparkfun.com | DEV-09716 | n | you'll need this to program the Pro Mini board, since it doesn't have onboard USB |
| total | 93.96 |
My current FLD and RLD board design is version 3. The PSI design is version 1.
You can read some information about my original (version 2) boards.
FreePCB (fpc) files. Download these if you want to edit or just view the board designs in the FreePCB application.
v3 FLD FreePCB file
v3 RLD FreePCB file
v1 PSI FreePCB file
Gerber files. You can use these files to order a set of boards from pcb.laen.org, or your favorite fabricator. You can also view or print the gerber files with GC-Prevue.
v3 FLD gerber files
v3 RLD gerber files
v1 PSI gerber files
You can order the 5 board set from pcb.laen.org. All you need to do is send an email to pcb-order@laen.org and ask for "R2D2 v3 board set" and you'll get the 5 board set for $35 shipped. He will reply to your email with confirmation and payment instructions.