Light Buddy 2 - The Design

 

Here is what the board looks like.  It is very simple, just a fancy way to control 6 LEDs to produce fixed (kind of) lighting effects.  No remote of any kind.

The voltage regulator, U2, will take up 16VDC and produce either 3.3VDC or 5VDC, haven't decided what voltage to run at.  The intended input is VUSB, so if it is 5VDC, it will just follow the input.  J9 is the power input (GND-VUSB-GND to help prevent incorrect connections).

J8 is a standard TTL/CMOS level RS-232 interface.  My intent is to allow the 6 outputs to be programmed in some fashion, TBD.  The problem is anyone who does this will need a RS232 to USB converter.  For me, this not a big deal, for some LEGO users, this may be a bridge to far.   So when you order it, I would program with the desired effects.  The buyer would pick from a selection of choices.  I have also considered a BT module that plugs onto J8 and J9.  Then you would use the Light Buddy Android App to update it.

The remaining parts are six N-FETs to drive the LEDs and protect the processor outputs from excessive current draw.

On the backside, the two circles is where small 1 x 1 round LEGO plates will attach to the PCB (super glue).  This allows the board to be mounted into the LEGO Model.

The processor is either PIC16F18326, PIC16F18346, PIC18F06Q40 or PIC18F06Q41 families.  They come in different memory sizes, I always start with the largest until I figure out how much I really need.

Finally, the absolute bane of my existence, connectors.  All of these are of the 2mm type.  But as you can see they are large compared to the board.  I have used smaller 1mm 2 pin connectors before, but they are very difficult to un-mate.  Everyone complains about them.  Obviously J8 doesn't need to be populated unless you intend on using the RS232 interface.  J9 could be soldered in.  That just leaves J1 for the LEDs.  They also could be soldered in, but that would make working with the LEGO model more difficult.  You should be able to plug in individual 2 pin 2mm male connectors into J1 for each LED.  I keep looking for a solution to this problem, but have not found anything yet.