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Teardown: XBox 360 USB Controller

By All About Circuits

Courtesy of All About Circuits

In this teardown, we will look at the internals of an Xbox 360 USB controller to see just how far gaming controllers have come. This controller doesn’t have a battery, but it can be used for Xbox 360 and PC gaming (Which comes in handy if you’re a Steam fanatic!)

The Controller

Back in the day, gaming controllers used either tactile or rubber membrane switches to allow the player to interact with video games. Now, controllers have all kind of integrated electronics and fancy actuators to maximize gaming experience. For example, many shooter games rely on vibrators (along with trigger buttons) to give the impression that a gun is actually being fired. So, in this teardown, we will see what goes inside a modern controller and how they are put together.

The controller has many buttons including the colored X, Y, A, and B buttons, the four direction pad, two analog stick controllers, two bumper buttons, two trigger buttons, a start and back button, a mic / headphone jack at the front, and a menu button (shiny X logo button on the front).

The back of the controller

The back of the controller

The back of the controller reveals 7 screws that keep the unit together (the 7th screw is located under the sticker). The white sticker shown in the picture is most likely a form of anti-tampering where the warranty is voided upon breaking it (i.e. if the user accesses the screw underneath the sticker is broken and thus the supplier cannot be sure if the damage was caused by the user). Below the sticker is the mic and headphone jack which is important for online gaming (mainly to abuse other players in FPS games such as Halo).

Close-up of the mic and headphone jack

Close-up of the mic and headphone jack

One of the seven screws that keep the unit together

One of the seven screws that keep the unit together

The controller uses a USB cable that can be plugged into a windows computer (i.e. it is recognized as a user input device). This allows the controller to be used with PC games in a similar fashion to games found on the Xbox (for example, Black Ops on the PC is not the same without an Xbox 360 controller).

USB cable connector

USB cable connector

Two bumper buttons and trigger buttons

Two bumper buttons and trigger buttons

Inside The Controller

With the screws removed, the inner workings of the controller can be seen. Some features which can be spotted very quickly include the dual vibrators, trigger actuators, and the main IC that controls the controller.

The xbox controller revealed

The Xbox controller revealed

The vibrators consist of motors with offset weights and the motors themselves are surrounded by foam padding. The offset weight shifts the center of mass away from the motor shaft which is why the unit wobbles when in operation (this is also why washing machines like to walk around when an item such as a brick is placed in). The motor is surrounded by foam, most likely to prevent damage to the unit when the motor wobbles.

One of the two vibrators found in the controller

One of the two vibrators found in the controller

While this is purely opinion, I find the trigger actuator very impressive due to the use of levers and shafts to convert a linear action (pulling the trigger) into a rotational movement. This is needed because the trigger input uses a potentiometer and instead of using an expensive sliding potentiometer, a cheap rotary potentiometer was chosen instead. As the trigger is pulled, it rotates around a point which pulls down on a lever. The end of this lever is connected to a small potentiometer which translates the trigger pull into a change of resistance.

Trigger actuator and potentiometer

Trigger actuator and potentiometer

 

Top Side Of The PCB

Removing the PCB immediately reveals the use of a rubber membrane with carbon contacts for the buttons. While there are many that prefer the mechanical feel of tactile switches, rubber keys provide good action for their cost.

The rubber membrane that sits below the buttons

The rubber membrane that sits below the buttons

The topside of the PCB shows many gold contacts (for use with the rubber membrane), and two thumb-stick actuators that provide user input for situations where precise control is needed. The thumb sticks consist of two potentiometers at right angles to provide position information on two axis (up-down and left-right). The thumb sticks also have tactile switches that can detect when the user presses into the sticks.

Thumb-stick mechanism

Thumb-stick mechanism

Bumper button

Bumper button

PCB Components

The bottom side of the PCB shows the main IC under an epoxy coating (called chip-on-board). These consist of a silicon die directly mounted onto the PCB and then wired up using gold wires to pads found on the PCB. This provides a cheaper alternative to using an IC with a package as the manufacturing stage involved with packaging the silicon die is skipped. However, this is only economical for large quantities which is why it is typically found only on PCBs that sell in the hundreds of thousands.  

The gold pads that surround the chip-on-board are most likely the remnants of an IC that was packaged (as opposed to the chip-on-board method). This may be one of two reasons; First, early production runs use a package IC until sales show that switching to chip-on-board is economical. Second, it may be for prototyping reasons where a package IC is used instead.

The main IC that controls the controller

The main IC that controls the controller

The PCB also shows many component pads that are unused which may have been as a result of switching from a packaged IC to a chip-on-board or the discovery that many of those parts were unnecessary. One other common cause for such an absence of components is due to EM control (or the lack of it). Firstly, the product is designed to pass EMC regulations (hence the many resistors, inductors, and capacitors), but once in production, many of the noise reducing components are removed (as they do not add functionality), to reduce cost (and thus increase profit). This is a very common theme for off brand products manufactured in China.

The main IC that controls the controller

Many parts “missing” on this PCB

More parts missing (such as the inductors top left)

More parts missing (such as the inductors top left)

Summary

This controller shows typical manufacturing techniques to keep costs down (removal of redundant parts) but also demonstrates some clever mechanical actuators to record motion and detect user inputs. What is fascinating is how gamers were satisfied with just a few buttons in the past. Now, controllers barely have enough buttons and sensors to keep gamers happy!

 

 Diagram made in Scheme-It