Marshmallow Shooting Gallery
We got our first marshmallow guns at Makerfaire NYC 2010 and they were a blast. After shooting each other we wanted to build some creative targets to shoot. Being the techies we are we weren't just satisfied with shooting soda cans off fences. Oh no, we had to bring this to the next level. For the marshmallow shooting gallery we wanted to design a range that was able to reset itself, trigger awesome effects and keep player scores. Also as more people built creative targets the gallery we wanted to make the system modular so it could expand year by year.
In order to make all the targets compatible we had to design some rules. The first was the targets need to have some electronics on them and make some kind of electrical signal. The easiest way to connect these distance targets was use old Ethernet cables, it's cheap and companies throw them out by the hundreds of feet when they upgrade.
The targets when hit would send some sort of signal to a base station. When the base receives the signal it would let the counter know to increment the players score.
Also this should be somewhat simple so you wouldn't need a massive micro controller to manage all of this. The easiest way we thought of doing it was to make each target send a pulse. A short pulse. The counter would count these pulses and increment it's score based on how many it received.
- Every Target module will have the following signals
VCC 5V - 5V power for the module GND - ground Player 1 - A pulse output to increments the counter for player 1 Player 2 - A pulse output to increments the counter for player 1 Reset - A reset signal from the base that tells the module to reset it's target
- Target modules will have a target for player 1 and player 2
- Target modules can output a rising edge for each time it is hit.
- Target modules should aim to draw 100mA at nominal use, at maximum it cannot draw more than 5V 500mA
For modules that cannot output a pulse train this module will be connected inline. It will trigger a single pulse every time it sees a rising edge. A simple D type flip flop should be able to do this using the clock as the input and the inverting output as the clear.
Alternatively the pulse can be put into an AND gate with one of the inputs being inverted through an inverter. The delay of the inverter will cause a momentary pulse every time the input goes high before the inverter can setup it's output.
This gate will take in all the inputs from all targets and have a single output to that players counter.
Multiple or gates can be cascaded to allow more targets.
The counter will count on a rising edge. If two targets are hit exactly at the same ms it will count as one point. If the pulses are short this should be a very unlikely event.
This will be a 2 digit seven segment display for player 1 and a second for player 2. They should be large and reset at the same time the master reset is hit.