The Making of Simon

I got a bug into my head several years ago to make an interactive Holiday Light display. At some point, I landed on Electronic Simon as the best interactive game that made sense. Colored Lights? Check!

Every holiday came around, and things were too busy, or I didn’t have the materials. This year, however, I realized that I worked for a company that made products that contained many of the electronic components I needed, just sitting there in the scrap bin of discarded prototypes. Relays! PIC microcontroller on a usable PCB!

I already knew that there were several open-source implementations of the Electronic Simon firmware for Microchip PIC microcontrollers out there. I settled on Andrew D. Vassalo’s as the simplest and easiest to port. He did his on a PIC 16F84, and I had on hand an assembled PCB with a PIC 16F690.

I had originally wanted 4 large letters or symbols up on the roof, and I wanted them big. Reality set in, and budget, and thus I started with a 4′ x 8′ of 1/4″ plywood that I had already, and some scrap 1×1″ and 2×4″ boards to for a frame.

My son, Rocketboy, volunteered to help paint the patterns on the board:

We found some LED lights of the four colors, 2×50 lights of each color. I mapped out where the lights would poke through the plywood, for a nice shape-defining look:

Drilled the holes…

Mounted the lights on the back with a stapler…

And tah-DAH!

Looks better at night.

Next, I needed a control console to mount up at the sidewalk so passers-by could play. More scrap plywood and 2x4s.

I ordered some arcade buttons from, $1.25 each, with built in LEDs. I drilled 1″ holes to place them in the console.

This is the tough part… I pulled a control board out of a discarded prototype from my job. It had the 16F690, a few FET transistors already wired to drive relays, and some easily wireable GPIO to input switch signals and output LED signals. In the end, the design was more or less like Andrew D. Vassalo’s schematic, with 4 extra pins used to drive FETs, which would be used to drive the relays for the holiday lights.

My original 5VDC power supply didn’t have the oomph to drive all four relays (600mA), so on a Saturday night with no easy access to a store that might sell an oomphier supply on short notice, I realized that our Apple iPod charger adapter was effectively a 5VDC 1 Amp supply. I co-opted it for the project, and it worked like a dream.

Below I mounted four 5VDC relays, also salvaged from discarded prototypes from work, in a plastic chassis from, you guessed it, a discarded prototype from work. The chassis already had built in 110 AC plugs I could use to plug the holiday lights in.

Fully assembled unit being tested by Scout.

I made a little stand so it could be used outside at the sidewalk.

The console in place, with the light board in the background, on some makeshift stilts to get it off the ground. I completely abandoned putting it on the roof once I saw (felt) how heavy it was.

Scout plays the game at night, to perfect results.

The machine in action, tested by RocketBoy: