Our goal for World Maker Faire 2014 is to have a non-video video game with us: Pi Pal Asteroid Blast. Using your laser cannon blast away the asteroids and save Chip as he flies through space on his way to the Maker Faire. (Yes, we know Chip is always in trouble somehow.) We hope the game is fun and shows makers of all ages what is possible with a little imagination and some basic knowledge. The game is controlled by a Raspberry Pi and programmed with Scratch GPIO.
Sometimes people see an end result and think they could never do the same thing because they believe the person who built it has all this “expertise.” Let me assure you folks, I am learning as I go here and anything I learn so can you. They key with any project is to break it down into small bite size pieces. My first task was to learn how to control the GPIO of the RPi. I did that with some LEDs. Next I had to learn how we could detect a laser hit. I looked up how to use photo resistors. Next I had to learn how to turn the LEDs on and off and sense when the photo resistors sensed the laser. I could do all this in Python, but I wanted it use Scratch so we could easily have some on screen interaction. Scratch GPIO does exactly that. For now, to keep things simple, we using a laser pointer as our blaster.
Using a breadboard we have hooked up two photo resistors as our sensors and two LEDs as our hit indicators. The photo resistors are set up to pull-up the pin on the RPi. When the RPi pin goes from 0 to 1, Scratch GPIO detects this and lights the LED and alerts on screen which sensor you hit. Even with only two sensors my son and I found ourselves playing and challenging each other for almost an hour. Who could shoot from further away, faster, one hand behind the back, quick draw? I think blindfolds are next. In typical 10 year old fashion we moved from the idea of a hand held blaster to a laser cannon. Construction of the laser cannon has also begun.
We will keep updating on our progress and you can learn right along with us. By the way, how many days left to Maker Faire?