Hardware Hacking: Making A Laser Gun

By Les Pounder. Posted

You'll need: Nerf Laser Ops Pro Alphapoint
Cost: £34.99
Where: Amazon Link

Nerf is mostly known for its range of foam dart-based guns that are sold around the world. However, the firm has recently released its Laser Ops range, which combines its plastic weaponry knowledge with Bluetooth and infrared (IR). What can we do with it, and can we hack it? Well, what are we waiting for?

General Construction

The guns are made of a stiff, yet easy-to-work, plastic that can be worked using hands and light power tools. The chassis is made up of three main parts: a left and right side that has the profile of the gun, and the solid front ’barrel’ section that is sandwiched between the profile pieces. The chassis is held together with 16 machine screws and a light amount of friction. When taking the gun apart, we see that the functional parts, barrel, IR dome, and the status panel are all modules that can be removed with ease.

Power

Just under the barrel there is a single machine screw, which when removed gives access to a pull-out tray that is used to store 4 × AA (LR6) batteries, totalling 6 V. We tested the guns with four rechargeable batteries (4.8 V) and they worked exceptionally well. This means that we can use a 5 V USB power bank; for example, those ‘candy bar’-shaped USB batteries fit in the space as if made for it. All we need to do is fabricate a male USB A power lead that connects to the gun’s power connections. This can be 3D-printed so that the battery slots in, or we can hack a USB lead to provide a quick power solution.

Electronics

At the rear of the gun there is a single circuit board. This board controls all of the functions present. It plays a sound when the trigger is pressed; it responds to a ‘hit’ and updates the rear status panel – very reminiscent to that used in the Halo video games. The main board has connectors for the status panel, which is a simple three-colour LED setup that shows the ammo and health status using green, yellow, and red. This board can be easily removed and repurposed in another project. The IR dome, a large purple plastic dome which sits on the top of the gun, houses three IR sensors which cover 270 degrees. The IR sensor unit can be removed and connected to an Arduino, which can be used to sniff out the IR transmissions, and possibly copy them for use with a sneaky extra gun. The dome also houses two typical LEDs that light up when the player is shot – these can be easily replaced should you wish to add a little flair to your gun.

On the top of the gun there is a semi-transparent plastic shell that houses an RGB LED, which is also inside a half shell of white plastic that diffuses the glow of the LED. This LED is used to show which team the player represents – typically games are red versus blue, which means that friendly fire is disabled. However, if the gun is set to purple, then any player can shoot any other player – this is selected by pressing the magazine load, located at the bottom of the grip when powering up the gun. Simply bump the magazine until the desired colour is selected, then press the trigger to start. This leads nicely on to the trigger and magazine reload electronics, which are simple open switches that connect to the main board. Be careful opening the unit: because the trigger has a spring to return it after each shot, it will ping away across your workshop.

If you look closely on the main board, you will see a Bluetooth connectivity chip – this enables your gun to connect to an optional app on your phone, which shows live health and ammo status. This 121MB app also provides live GPS location data for players (if they are also using the app) and it can be used with VR goggles to create a virtual shooting gallery using VR drones, or set up team battles in a lobby system.

The main board houses all of the electronics for Bluetooth, sound effects, and keeping track of our health and ammo

At the top of each gun is a dome that contains three IR receivers, giving us 270 degrees in which we can be hit

Infrared

The Nerf Laser Ops Pro guns use IR signals similar to those found in the remote controls for your TV, Blu‑ray, and cable boxes. But why? Well, lasers are a bit dangerous and will cause eye damage. But IR is safe and it has decent range, which we can easily change via a switch on the gun. So, setting the gun for outside use means we can run around and hide, taking shots when enemies approach. So what can we do with IR? Well, using an Arduino, Raspberry Pi, or other board and an IR receiver, we can determine the contents of the IR transmission. Once we understand what the guns send, we can instruct the Arduino to send that transmission. So we can build our own IR guns that react to sound, sensors, and start firing. Or, we can create our own targets that react to being shot, and maybe shoot back!

Conclusion

If you’re building a prop weapon for a convention, then the Nerf Laser Ops Pro range is an ideal base on which to build. The electronics are modular and easy to hack, and they can be used in other prop weapons quite easily: all you need is an Arduino, a multimeter, and a little patience while you determine the pinout for the IR sensor, LEDs, etc. In fact, the status panel is begging to be used in a Master Chief cosplay.

Hacking a better power source using USB batteries is a quick and easy project, and one that should be the first thing that you do. The next step is to hack the Bluetooth connection and use it to trigger effects in remote devices. Reload the magazine and have your prop future soldier cosplay light up. We can do this using a Raspberry Pi, scanning for Bluetooth MAC addresses. When discovered, it can trigger a reaction. All you need is a Pi and a little Python code!

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