Friday, 25 October 2013

Electronic quick draw toy gun

While we're waiting for the pcbs to arrive to assemble our first "proper" boardgame prototypes, we've been trying out different ideas for re-using the technology in different board games. One idea that has generated some interest is a Wild West skirmish game.

Of course, no Wild West game would be complete without the fast-draw shootout at High Noon.
Originally we thought that, in a two player game, each player could have a button. After a specific signal, first to hit the button wins the shootout. It seemed like a quick and easy way to add an extra element to a Wild West themed board game.

But then, of course, we had to go one step further. With guns.

These were little plastic toy guns (are toy guns hard to find these days or what?!) from a local pound store. Or it may have been a 99p store. But you get the idea - cheap, plastic guns, with a hammer on an elastic band. Perfect!

The idea now is that two players face off, first to draw their gun and pull the trigger wins the shootout.
That's great - except just replacing the pushbutton idea with pulling the trigger means a player could - in theory at least - leave their gun in the holster, shoot themselves in the foot and claim to have won the shoot out.

We needed a way of checking to see if the gun was at least out of it's holster - a simple tilt switch would suffice! We did originally try using two tilt switches, to measure if the gun was roughly horizontal, but this proved problematic: if we checked the state of the tilt switches at the point where the hammer came down on the gun (the point at which it would normally fire a bullet) the vibration of this could sometimes cause a false reading: the gun may be perfectly horizontal, but because of the shock/movement, the tilt switch reported no connection.

So the design was simplified - the tilt switch can detect when the gun is vertical, and when the gun has passed through the horizontal plane. Once the gun has at least passed through horizontal, we set a flag and transmit this data when the trigger is pulled. It's not perfect, because the player could be pointing the gun at the ceiling rather than at their opponent and still register a successful shot - but it's better than them being able to shoot at the floor and claim to have fired on their opponent first.

For testing, we've got wired connections going to a breadboard. But also on the breadboard is a 433mhz transmitter (the little square thing with four legs) and on another board we've a receiver. So we're able to send data wirelessly from the gun to a host controller, meaning we can stuff all our electronics inside the gun and have a completely wire-free controller.

Here Stephen is testing the gun-flicking action - registering when the gun has been raised to horizontal (i.e. removed from it's holster) and registering when the trigger has been pulled (and the gun has been fired).

Although there are wires everywhere and it doesn't look anywhere near finished, we concluded that this was a successful test: everything we wanted to test worked, and the gun did report - over a wireless radio connection - it's status when the trigger was pulled.

Now all we need to do is find a supplier of larger toy guns - with a gun designed for a small child's hands, you're just as likely to flip the gun out of it's holster and throw it across the room as to get your grown-up-sized fingers around the handle properly!

No comments:

Post a Comment