Noob Tries to Make a Pii U (Wii U Retropie Gamepad)

[BlueWeaselBreath]

I am a 33-year-old man, not extremely intelligent, with very little experience with electronics and getting a little too old to learn new things easily, but I’ve always wanted to gain skills in this area, so I’m going to try to build a Retropie machine in a Wii U gamepad! I have been inspired by the similar projects undertaken here by BanjoKazooie and IrieMars and will be referencing their threads heavily because, as alluded to earlier, I don’t know what the hell I’m doing. I won’t leave out any information that SHOULD go without saying, because I wouldn’t have known it had it not been explicitly explained elsewhere at some point. I won’t use jargon, without defining it, because I don’t know any.

I’ll be keeping a build log here 1) to keep myself accountable with this project so I maintain forward momentum; 2) so I can get assistance from the community if I hit a brick wall, which I most certainly will; and 3) to help and inspire other noobs who want to undertake this awesome project or others like it, but are completely befuddled and intimidated by the brilliant and knowledgeable folks on this forum who know what they’re doing.

After I’m done, I’m going to work it all up into a straight-up, easy-to-follow, How To guide (probably on an external site) that any schlub like me can follow, even if they’re not comfortable in the idiom of electronics.

The process will probably take me a very long time — many months at least — due to some realities of my time, budget, living situation, and inexperience, but I’m hoping that the progress will at least be regular, even if it’s slow. And I hope that the audience for whom this build log is intended will appreciate it!

I have ordered my first few parts — a Wii U gamepad, an LCD screen, and a circuit board for the screen. I have a Pi 3 already that I can use to test the video hookup but I’ll likely buy another one because that one is hooked up to my TV and I want to keep that one there.

Please feel free to send along any comments, suggestions, or encouragement, but — for reasons that should be clear above — keep it straightforward! Thanks!

[Trekintosh]

Good luck! I really appreciate how you're realistic about the project taking months, unlike myself who thinks I can bang out a project in a week that ends up taking a year.

I'm rooting for you! It'll be a great learning experience, that's for sure.

[xouliox]

Good luck.
Few days ago i stard a similar project with a wii u gamepad. But i go with a mini pc and windows 10 with retroarch and steam.
At the moment iam waiting for the display and the connectorboards for the teensy analog stick connections.

[BlueWeaselBreath]

Thank you for the kind words and encouragement!

One thing I can do before the parts arrive is to make up a definitive materials list for this particular build, based on a careful scouring, distillation, and compilation of various forums and posts of people doing this project. This post will be entirely dedicated to the gamepad parts you'll need, and the next will be the other components.

Parts Needed

1) Wii U Gamepad - you only need certain parts of the pad, outlined below, for this particular build. Maybe you can figure out how to use more of the original parts in your build, but here's all I know how to use for mine. Depending on what you find, it may be cheapest to buy a nonworking gamepad ($40-$50) and just remove the parts you don’t need (and re-sell them if they're working!). The best deal seems to be to buy the gamepad shell with just the buttons and connectors still in it and no other guts, but I couldn’t find that, so I ordered a full Gamepad with a wonky touchscreen and bad battery. I won’t need the touchscreen functionality and I’ll be getting a new battery anyway. Below are the parts of the Wii U Gamepad you’ll need (they can be purchased individually if necessary, but I did the math and it’s much more expensive to buy them all separately than to get a broken one -- if anything in my gamepad doesn't work, I can buy that component separately later).



1a) Gamepad shell/case - of course. This is what you’ll put everything in.


1b) Touchscreen digitizer - the clear plastic cover that goes over the fragile LCD screen, protecting it and turning your finger touches into inputs the Wii U understands. Even if your finished Pii U isn’t going to have touch screen capabilities, you need this piece to cover your screen. The original one that comes with the Wii U has an attractive bezel around it that will look good on your finished Pii U, but aftermarket ones may not, and a gap may be visible. You can’t use the original Wii U LCD screen with this build, but I hear on some gamepad units the LCD is fused to the digitizer, so if you can’t separate yours, you’ll have to get rid of them both and get a new digitizer.


1c) Buttons/triggers/sticks - there’s the two shoulder buttons (L & R), the two triggers (ZL & ZR), the nine face buttons (A, B, X, Y, +, -, Home, TV, and Power), and the D-pad. The buttons have little conductive rubber backings that you may have to buy separately if you’re getting everything a la carte. You’ll also need the covers for the two analog joysticks (the joysticks themselves are little gadgets attached to circuit boards).


1d) Button circuitry - you’ll need the joystick mechanisms, which are attached to their respective circuit boards. The boards will need to each have a white ribbon cable connector. The buttons, when pressed, activate a flexible plastic circuit and connector, and you’ll need this too; actually two of them (one for left side, one for right). These come attached to the following part, in the original gamepad, as seen below.


1e) Button housing - big chunky white plastic pieces that hold the buttons and joysticks, one on each side. You can buy these with the flexible circuit/connectors attached.


1f) Speaker drivers – these are the two little round speakers in the Wii U, and unless you only ever want to use headphones with your Pii U, you’ll need the original speakers or replacement ones


1g) LCD mounting bracket – this is a large plastic rectangle with a grid of crisscrossing pieces that holds the original LCD screen into the Wii U. If you don’t have one of these, you’ll need some other solution to hold the screen up. Some modders have used a custom-made mount, and this also allows the other components to be mounted too, but the original bracket is a pretty simple solution.

1h) Screws – you’ll need the original Wii U screws, or a replacement set, to hold everything together. Some of the original screws are Phillips-head while other screws are tri-wing (requiring a screwdriver with a special Y-shaped tip). Nintendo uses these screws sometimes to make it harder for consumers to open up their hardware. You don’t need to buy tri-wing screws if you’re replacing them, just Phillips. There are a few different sized screws (all tiny) used in the gamepad, though, so that may complicate things a bit. I'll try to update this with some measurements when I have them all out.


1i) Lower button board (optional) – if you want to use the buttons (labeled “Home,” “TV,” and “Power”) and indicator lights along the lower region of the gamepad, you’ll need the circuit board that sits behind there and controls them. The original Wii U control board is the best solution, but some modders have custom-made their own. I didn't have the skills or wherewithal to make my own, so I'll be using the one included with the gamepad.

EDIT - added some images.

[BlueWeaselBreath]

Parts Needed (Continued)

Here are the non-Wii U components and materials you’ll need to do this particular build. I will update this gradually as I decide upon specific components, and I can link to them.


2) Raspberry Pi 3 - if you're on this forum, you probably know that the Raspberry Pi is a single-board computer. The Pi 3 is the best version for this project. You'll have to dismember the Pi that you use in your Pii U, so there's no going back.


3) LCD Screen - the original Wii U LCD unfortunately has wiring that is incompatible with the Pi unless you are very advanced at electronics and can obtain the right proprietary parts, so you'll need to get a new one. The 6.5" AT065TN14 is commonly used with the Pi, fits perfectly into the gamepad, and can be found many places online.


4) LCD Controller Board - the LCD screen won't do much without the driver board to run it, so you'll need that, too. It's model #VS-TY50-V2, and it often comes with a separate input board and a remote control, which you won't need for this project. Also, it's often sold together with the LCD screen, but for some reason getting them together can be more expensive than buying them separately. These have a 5V power input, but sometimes they come with a 5V USB input for the power and other times they come with a 5V DC barrel jack. It’s not important which it is, as you’ll be cutting the connector off anyway, but it might make it easier to test beforehand if you get a power connector that’s convenient for you.


5) Teensy Microcontroller - you'll need this gadget to translate the Wii U controller presses into a format that makes sense to the Pi. You will be able to specify with the Teensy what each controller input does. The Teensy 2.0 is good enough to do everything you need here, and small enough that it will fit nicely into the Wii U shell. There are more advanced versions of the Teensy, but they're larger (real estate in the Wii U will be precious) and more expensive than we need.


6) USB Sound Card - devices that produce digital sound usually use a digital-to-analog converter (DAC) to turn the digital audio signal into a format your ears can recognize. The Pi 3’s headphone jack uses another type of conversion technology called pulse width modulation (PWM) that gets inferior sound to DAC, so it’s recommended to use an external DAC sound card for this project. You can get a cheap and simple one, even one made for external use, and just take off its case and pop the electronics into your Wii U case. I initially recommended finding one with a built-in jack, but I have since realized that if you want the volume control knob you install on the PiiU to control your headphone volume (and of course you do), you’ll need to remove the jack that comes on your sound card anyway (thus destroying it), as I did, in order to wire a volume control in there; thus, a built-in jack is not preferred, but not hugely difficult to remove if that’s all you can find. I recommend a 5V USB DAC board with a PCM2704 integrated circuit (a chip made by Texas Instruments that’s used in a wide array of USB sound cards). They can be found all over eBay by searching for the above keywords; they have the headphone jack built in, but you can just take it right off with plyers and soldering iron. You’ll also want to remove the USB connector from this board, so if you find a board without a headphone jack and USB connector preinstalled, that’s even easier!

So then you’ll also need to get a separate headphone jack, a standard 3.5mm jack. I will find and recommend one here soon enough.


7) Amplifier Board - you’ll also need an amplifier between your sound card and the speakers. You’ll want a Class-D amp (the class refers to the type of amplifier, and Class D produces sound in a highly efficient manner). Go for a 2x 3 Watt amplifier board (the 2x denotes two channels, i.e., stereo) with a PAM8403 amplifier chip.


8) Potentiometer (“pot” for short) - this is a resistor (a component that reduces electrical signal) with an adjustment knob to dial resistance up and down, which in this case will serve as your volume control. You’ll want a gear-shaped pot or a slider-style so it’ll look natural on with your Wii U gamepad. Pots are rated in Ohms, a unit of resistance, and for this use, something between 10k and 20k Ohms (the “k” stands for 1,000, of course) will work.


9a) Batteries - you’ll need some rechargeable batteries so you can play this Pii U on the go (otherwise, what’s the point?). Lithium-Ion (Li-Ion) batteries are best kind for this project, or Lithium-Polymer (LiPo) batteries (which are the same type of battery made of a different material). I would recommend a pair of 3.7V cells of at least 3400mAh (milliampere hours is a unit measuring the capacity of a battery — i.e., how long it lasts before running out). Higher capacity batteries mean longer playtime, but capacity is partly a function of size, so very high capacity batteries won’t fit in your Pii U. Also, the larger capacity battery you get, the longer it’ll take to charge, so don’t go nuts here — anything more than 8000 mAh (that’s TOTAL, if you have two battery cells in your setup) will probably take an inconveniently long time to charge. A note on nomenclature: technically each individual unit is a “cell,” and the whole setup is the “battery.” Just to be pedantic.

You could also look for a battery labeled 7.4V 2S, denoting that there’s two cells inside each one (and the total voltage of each cell adds up to create a battery with double the voltage, hence 7.4V). You could theoretically get longer battery life with a 2S battery if you find one with high capacity, but the problem will be space inside your Pii U, as large capacity 2S batteries tend to be pretty chunky. So I recommend you find two 3.4V (1S) cells and wire them in series, as I will do in this project, to effectively create your own 2S 7.4V setup. It’s very important that the two cells you use be identical! If you mix two different voltages, capacities, brands, etc. you’re likely to create a situation where they get charged unevenly and this leads to big problems.

Lithium-ion cells tend to be named for their size, and for this project, I’ll be using two 18650 batteries, which are shaped like AA batteries but larger — 18mm in diameter and 65.0mm in length, actually, hence the name 18650. A final important note here is that due to the chemicals used in Li-Ion and LiPo batteries, they’re very sensitive to mishandling and dangerous (flammable and all that, can cause injuries) in a way that your standard household batteries are not. If you know what you’re doing, electrically speaking, lithium cells are perfectly safe, but if you don’t, please read up on Li-Ion/LiPo battery safety before working with them so you don’t accidentally do anything to hurt yourself or burn down your bungalow.

You can get Li-Ion 18650 cells in either protected or unprotected form. Panasonic is a good, reliable brand if you want to buy the unprotected, which are a little bit cheaper. Protected cells are just unprotected cells that have been packaged with little protection circuitry on the ends of the cell that prevent the battery from being overcharged or undercharged, which keeps the battery from permanently dying or bursting into flame. A number of reliable companies such as Orbtronic, KeepPower, Eagletac, and Nitecore sell protected cells for high-end flashlights, and these have legit cells like Panasonics inside, which is a good bet. Protected cells are several millimeters longer than unprotected due to the extra circuitry and may add an extra bit of resistance, potentially leading to slightly decremented performance, but are safer for inexperienced builders than unprotected. If you buy unprotected cells, you NEED to get an extra component called a protection circuit module to safely use them (see corresponding section below).

I’m using a pair of KeepPower 18650 protected cells with a capacity of 3500mAh each. The consensus seems to be that 18650s can’t reliably get much more than 3400 or 3500 mAh with current technology, so be critical if you see higher capacity labeling on an 18650 and test them yourself.


9b) Protection circuit module - a protection circuit is a necessity for your battery cells, because if lithium batteries get overcharged or undercharged, they become damaged, and sometimes this can lead to fire. If you purchased unprotected cells, you need a separate protection circuit module/board to ensure this doesn’t happen (some charging modules have overcharge/undercharge protection, though, and if you have one of these, a separate protection board is less important; see Charging Module section, below). Another type of protection that is not directly offered by protected cells (or by most charging modules either) is balancing, which is important if you wire your cells in a series (and not needed if they are wired in parallel); if one cell is fully charged before the other, how does your charging module know to stop charging it but keep charging the other? Even some dedicated protection circuits don’t offer balancing protection, and it is less important than over/undercharge protection, which can indirectly help keep the cells in balance. If you have your cells in series and want to be safe, you can do as I did and find a board that offers balancing, though. Make sure your board is for the right number of cells (it’ll be labeled 1S, 2S, or so on).

To sum up, over/undercharge protection: critical. Balancing protection: useful. If you can’t find a board that offers both, get the over/undercharge protection (3 Amp or higher). Since I already have over/undercharge protection in my cells, I got a board designed to provide only balancing protection for a 2S battery. It can’t be used without over/undercharge protection, but it’s good if you have such protection in the cells or in your charging board.



10) Charging circuit (and port) - you’ll need this so you can recharge your batteries. A 5V 1A charger module will do the trick, and get one with a micro-USB port (or get one separately, read on), which will be what you plug in to charge it. You will also need a protection circuit (see previous section) to keep the batteries from overcharging, overdischarging, and otherwise getting ruined, but some charging modules have a protection circuit built in. If you’re going for a 3.7V (parallel) battery setup, look for a TP4056 charging board — it’s inexpensive and some listings are for newer models that have an inbuilt protection module. If you’re using a 2S 7.4V battery setup (two 3.7V cells in series) like I am, I recommend the TP5100 board. This board doesn’t tend to come with the actual USB charging port on it, so you’ll need to get it separately if you go with the TP5100, in the form of a Micro USB to DIP adapter board.


11) Voltage/Power converter - because the voltage from your batteries will not match the recommended input voltage for the Pi 3, which is 5V, a device called a DC-to-DC converter is needed, to change the voltage level coming from your batteries. If you went with the two 3.7V batteries, you can choose to wire them in parallel (each battery having its own circuit), which is simpler, or in series (one big circuit going through both batteries), which I will do here and will lead to better performance.

If you go with a parallel setup, you’ll need to increase your voltage to power your Pi (yeah, there’s two of those 3.7V batteries but if you’re wiring them in parallel, the voltages wouldn’t add up, they stay constant); to increase your voltage, you’ll need a boost (or “step-up”) converter. The recommended one for this project is the Adafruit Powerboost 1000 Basic. It’s designed to take in voltages as low as 1.8V and boost them to just over 5V.

If, on the other hand, you want to wire your two 3.7V batteries in series as I’ll be doing in my project (chaining them up this way means you add their voltages), or if you went with the larger 2S battery for your Pii U, your battery voltage would be 7.4V, meaning your voltage is too high for the Pi! In this case, you’ll need the opposite type of converter, a buck (or “step-down”) converter. A good one of these would be the Pololu 5V, 5A Step Down Voltage Regulator D24V50F5.


12) Power switch - to help keep it slim, the Raspberry Pi doesn’t come with a power switch on it. It powers on automatically when it’s plugged in, and powers off via a software/operating system command. Of course, the typical power-on method won’t work in your Pii U since it will always be attached to a power source (i.e., the battery) inside your gamepad, so you’ll need a power switch to turn it on (and off too, if you get fancy with it). If you know what you’re doing, this is a simple circuit you can make yourself, but I don’t know what I’m doing so I’ll probably end up buying it. Why can’t you use the existing power button on the gamepad’s lower button board, you ask? Sure, you can! But recall that it originally was connected to the Wii U gamepad motherboard, so you’ll still need to wire it to a new switch circuit, so get an on/off switch no matter what. I am using the Pololu Mini Pushbutton Switch, Model SV.


13) HDMI flat cable - to attach your LCD screen to your Pi, you’ll need an HDMI cable. But you’ll want a short, flexible flat cable (FFC) so it takes up as little room as possible. Of course, advanced users can just desolder and remove the HDMI connectors from the Pi and LCD and connect an FFC straight to the two boards. This saves room inside your gamepad shell! But it’s also tough and risky if you don’t know what you’re doing, and I don’t want to risk damaging my components so I’ll just use the damn HDMI as-is. (In case you’re interested, HDMI stands for High Definition Multimedia Interface.)

14) MicroSD to SD adapter cable - the Pi has a MicroSD card slot, which is used for booting and file storage. Once you have your Pi in the middle of your finished Pii U, you’ll want easy access to that slot, so it behooves you to get a flexible ribbon cable to extend from the Pi slot to the edge of the gamepad shell, so it’s externally accessible. If you get a cable with an SD slot, rather than another MicroSD, on the far end, then you will be able to use either a full-size SD card or (with an adapter) a MicroSD card, so I recommend getting a male MicroSD to female SD cable adapter.


15) FPC to DIP adapters (connectors and boards) - to connect the original Wii U gamepad controls to the Teensy microcontroller so you can use them with the Pi, you’ll need an adapter, because the original controls are flexible printed circuits (FPC), but the Teensy is going to need wire connections, not FPCs. Luckily, you can get FPC connectors presoldered to printed circuit boards (PCBs) that are designed for what’s known as dual in-line package (DIP) connectors — those black rectangular components with two rows of pins. But instead of DIP components, we’ll just be soldering the output wires directly to the boards. Then you connect the input FPCs from the WiiU controls to the FPC connectors on your little boards, and boom, you’ve got an adapter. You’ll need two of these for the project, one for the left side controls and one for the right. If you’re hardcore, you can get the FPC connectors and PCBs separate and solder them yourself, but this is by all accounts a tedious and extremely challenging task, so just buy them preconnected. You want an adapter board with i) a 10 pin FPC connector with 0.5mm spacing, and ii) a 10 pin DIP connector with 2.54mm spacing.

16) USB jack - if you want to be able to easily plug in a keyboard for configuration purposes or a flash drive to load games to your machine, you’ll need to have a USB-A (that’s the standard one you always see in computers) female jack accessible from your Pi. Sure there’s already some on there, but they take up a lot of room in the gamepad shell, and they would be in the middle of the gamepad when you close it up, not easily accessible. The goal is to remove the USB jacks from the Pi and then run wiring from the area where the USB jack used to be to a USB jack that’s farther away, i.e., accessible from the exterior edge of the finished gamepad. If you can remove the original jacks from the Pi without destroying them, good on you, but this is much harder than it sounds, so you will probably need to get a new one. You’ll need a USB 2.0 or 3.0 (the Pi can’t take full advantage of 3.0, so 2.0 is sufficient and probably cheaper).


17) Ribbon cable - to connect the controllers, you’ll need some 10-conductor copper ribbon cable. That’s 10 wires attached side-by-side, and get the rainbow kind so you can differentiate them as you work with them. The most common pitch (i.e., spacing) is 1.27mm, which is fine. And the common wire thicknesses for these are between 22 and 26 gauge, and any should be fine, with a smaller gauge preferred if you have any choice in the matter (higher numbers are smaller in the American Wire Gauge). A meter’s worth of cable should be plenty unless you somehow goof up and need extra.


18) Silicone hookup wire - you’ll also need to connect all your components and run power to them and whatnot, so you’ll want some more copper wire, this time with two conductors. 22 gauge is fine here (too-small wire will mean more resistance and decreased performance). The wire with black and red silicone jacket are what you want, since that is the standard color-coding for electronic wiring of positive and negative, as you well know.


19) Battery holders (optional) - You’ll need to hook up your battery cells to the rest of your circuitry. If you have a brick-shaped or flat LiPo battery, it will likely have your positive and negative wires running out of it, ready to connect. But if you get the cylindrical 18650 cells I recommended, you’ll need some way of connecting them. You theoretically can solder the wires straight into the terminals of a Li-Ion cell, but it’s a somewhat involved process that can be frustrating and dangerous without the right knowhow and special tools.

A much easier solution, which I recommend here, is to get a battery holder for each of your cells. You want the (usually black) plastic rectangular spring-loaded compartment — like the type of setup you’ve seen your whole life whenever you pop batteries into a gadget — with a lead wire coming out of each end. The benefit of these is that it’s easy to pop the batteries in and out if you need to change them, and it’s much safer than trying to solder Li-Ion batteries. The downside is they will take up a little extra space inside your Wii U shell and likely add some resistance to your circuit, potentially compromising performance a tad. Depending on your skill level, your decision may vary, so I am listing battery holders as optional.


20) Resistors (optional) - You want to be able to monitor how much life is left in your battery so it doesn’t die while you’re playing! If you use a 3.7V battery setup, there are a few possibilities for creating a battery monitor with just the components above, but I’m using a 7.4V battery, which has too high a voltage to connect directly into the 5V Teensy (which can monitor the voltage and show indicators or take action when the voltage is at a certain level). So I will be using two 2.2k Ohm resistors to create a voltage divider — a simple device that takes an input voltage and divides it so the output voltage is smaller. This particular value of resistor results an output voltage of exactly half (3.7V) of the original battery voltage. This is now low enough to run into the Teensy (which, recall, has a 5V capacity), which will read this voltage as the battery charges and discharges. Since the Teensy is reading a voltage half that of the true battery voltage (due to our divider), we’ll know that the true voltage of the battery at any given time is twice the value that the Teensy is seeing. Simple!

21) Noise filter - To avoid noise in your audio signal, it is recommended that you incorporate a component known as a choke. A choke is an inductor (inductors store energy in a magnetic field when electrical current is passed through them) that blocks high-frequency AC current while allowing low-frequency current to pass through. It might make sense to use a common mode choke, a type of choke that suppresses noise on both lines by having two separate windings. Unfortunately, while I’ve had many components recommended to me by user Banjokazooie, to whom I am grateful, the specs involved are so complex to a noob like me that it is currently hard for me to tell you what to look for in a way that will be illuminating. I’ve been told that the interference spike you could get without using this component is around 700 kHz, but when shopping for these components, the specs always describe the impedance (in microhenries) but often don’t describe the frequency range or amperage. I’ll welcome any help in this regard, and please explain it to me as if I’m a ten year old, so I know what to recommend to people. If you get brave and try building this without the choke filter, let me know what happens — I expect there would be some bad noise.


22) Heat sink(optional) - To avoid the Pi overheating while you use it, you may want to put a heat sink on it. These are just inexpensive pieces of aluminum that stick to some of the main Pi components using conductive adhesive to conduct heat away. The Pi that I have hooked up to my TV overheats when I play Playstation or even SNES games on it, so I thought it'd be a good idea to play it safe with this Pii U project to avoid this happening. It protrudes another centimeter or so, taking up precious space, but I think it's worth it for the peace of mind. These often come two in a pack, with a big heat sink for the CPU and a small one for the Ethernet controller. Since we've removed the Ethernet port, the Ethernet controller is unlikely to get too hot, so you don't really need the small one, but I went ahead and stuck both of them on anyway, because what the hell. Make sure you get a legitimate brand, because ones with bad adhesive can insulate the heat rather than conducting it away, and make things worse. Please excuse the stock photo, but I forgot to photograph mine before I attached them.


23) Insulating plastic - If the back of the new LCD screen you’re installing has exposed metal, then there’s the possibility that it could conduct the electrical signal that you actually want to remain within the circuitry you’ve built, thus shorting the circuit and ruining everything. This would be a bad thing! So get a thin layer of plastic to cover up the metal on the back of that LCD. I bought a 50-cent notebook with a plastic cover from Staples and cut out a 9cm x 15.5cm rectangular piece of plastic. Easy!


—————-
EDIT(S): I have added more information gradually to better help you find the components you need and give you more info about the components in case you’re as clueless as I was before starting this project. I’ve also added battery holders as an optional component. Also, I decided to use a 7.4v battery setup, so have changed my recommendation for the charger module to the TP5100, although I have kept the info on the TP4056 there as well. I now recommend 22 gauge for the main hookup wire. I also added resistors as an optional component for 7.4V setup, to create a battery monitor.

8/10/19 - Added info about noise filter.

8/9/20 - Added info about insulating plastic.

[BlueWeaselBreath]

Wii U Gamepad Teardown

I got my Wii U gamepad in the mail, so let’s do a teardown!



It was advertised on eBay as missing a battery. Also, the top-left of the touchscreen was nonresponsive. Both of these things were fine for the Pii U project. I don’t mind telling you it was $40 (USD). Upon receiving it, I noticed a small scratch or gouge on the screen. Also, the battery cover had a broken screwhole and was missing a screw (and thus stuck out on that open corner). Some foul-looking schmutz was caked on the back of the gamepad and inside the battery compartment. My guess is that it’s some sort of dried adhesive but it almost looks like the plastic is melted.



Turn the gamepad facedown and remove the screws holding on the battery compartment on. Unplug the battery if you have one (I didn’t). Then pry up the ten little rectangular screw covers around the edges on the back of the gamepad (those were missing on mine too) and unscrew these screws with a tri-wing screwdriver. The back will now pry off easily. Slowly! There will be one little set of wires stretching between the two halves of the Wii U, as shown. Gently pull the little white connector with tweezers or fingernails to unplug it, and you can separate the two halves of the gamepad.

https://i.imgur.com/EmmBKIT.jpg
Don’t lose the volume slider, a small black rectangle that may be loose at this point. Put it somewhere safe, just in case you want it later.


Take out the L & R shoulder buttons and set them aside so they don’t get lost. Now let’s get that bottom button board out of there.


See the thin wires on the right of the charging board leading to the near field communicator (NFC) module (this is what reads Amiibo)? Unplug it from the NFC chip by pulling gently.


Then look at the tiny little ribbon on the left of the charging board leading to the button board underneath (it's in the center of the picture above). Disconnect it by popping open that tiny brown part of the connector like a little hatch or flap, then pulling the ribbon out. This kind of connector is called a zero insertion force (ZIF) connector, so if you need to use much force to get it out, you’re not doing it right.


When it’s out, remove the charging board by lifting it straight up.



Next, there’s a white plastic molded spacer to remove. Take out the two Phillips screws, then unthread the microphone wires that goes over the right side. Now that white plastic comes up.



Disconnect the ZIF connector on the motherboard holding the fat ribbon that connects the lower button board to the motherboard, then your button board comes right out!



Next, let’s get those big white button casings out. Take out the Phillips screws surrounding each one, then unthread the speaker driver writing that crosses over the casing on the left (which holds the right trigger button because the gamepad is upside down).


Each casing is attached to the motherboard with another ZIF connector, so pop those open and lift the casing right up out of there.



This will uncover the analog joystick boards (one on each side), and those can be taken out too! They are each held in place with two tri-wing screws and attached to the motherboard with a connector. Push down on the white tab and gently pull out the connector, and lift the joystick boards free.


Now is a good time to take out the conductive rubber backings from the buttons and set them aside. Now the buttons will be loose, so take them out, too. When you remove them, be sure to do so by haphazardly turning this half of the gamepad upside down without holding the buttons in, so they all fall out simultaneously and bounce everywhere across the table and floor, like I did, so you lose them and have to spend five anxious minutes on your hands and knees rounding them up.


Now it’s time to take out the motherboard. There are a few wire connectors to gingerly unplug (with tiny tweezers or fingernails), including the speaker drivers.


The wireless module at the top-left of the board is stuck with an adhesive to the motherboard, but it can be peeled right off with a little force. Now remove the screws all around the motherboard.



Finally, remove the three FPC ZIF connections (one fat one and two teensy ones) by lifting up the little hatch as before. The motherboard will lift right out, and the near field communication module on the right can come out too.


Now you can remove the speaker drivers and microphone (the mic is that little piece covered in the clear silicone that sits at the bottom of the gamepad, as shown above).



The dual antennas at the top of the gamepad can now be unthreaded from the screen bracket and removed.




Now, unscrew the four screws in screen bracket, remove it, and the LCD and touch screen digitizer will lift right out. I’ve heard that on some models, these are fused together, but mine were only lightly stuck together with an adhesive that allowed me to separate the two components and slowly peel them apart.


Don’t forget to unscrew the two little screws holding the stylus holder in, and remove it from the inside of the shell.


Also, the rumble assembly is above the inside of the battery compartment, and can be unscrewed as well. I wasn’t able to pry mine off for some reason, but no sweat, because I just shaved it down in a later step when I shaved down the rest of the WiiU shell interior.

My gamepad is now in pieces inside a plastic shoebox. Now time to wait on the rest of my components to arrive (as I can afford to order them) and start building!

[Trekintosh]

I just want to say you are doing an absolutely fantastic job documenting this. Looks like a super pro tutorial at this point.

[BlueWeaselBreath]

Preparing Your Pi

In order to make your Raspberry Pi fit into your Pii U, you’ll have to slim it down by removing the unnecessary junk from it. This is one of the most challenging and tedious parts of the project. I was greatly helped in this endeavor by Adafruit’s Diet Raspberry Pi guide, which you should read too, and by IrieMars’s sudomod thread.

I must give credit where it is due and acknowledge that the layout of my guide image was directly modeled off of IrieMars’s own.

Ok, ideally, you’d slim down the Pi by desoldering each component and then removing it gently from the board. But in actuality, desoldering circuit board components properly takes a lot of skill and good tools, so you’ll be most likely damaging each of the unneeded components enough to remove them from the board, then removing their residual junk via desoldering. You’ll need most or all of these tools and supplies for the job, in decreasing order of importance: soldering iron with a fine tip, desoldering pump (aka “solder sucker”), flush cutting precision pliers (I used a diagonal offset one), a pair of standard pliers (e.g., good old fashioned combination pliers from all-in-one toolset), precision flathead screwdriver or other thin prying tool, desoldering braid/wick, some solder, and a helping hands soldering grip tool or clamp.

A couple of general notes about this process. First off, wear eye protection or glasses, because it only takes one tiny shard of metal popping into your cornea to ruin your week. Don’t worry about trying to salvage the components, and it’ll make your job a lot easier. In general, you want to clip the pins off the bottoms of the boards as closely as possible using your flush cutters so you can more easily access the solder, and there’s less metal to sink the heat, meaning the solder on the board will melt faster. When you’ve clipped the pins from a component, hold your soldering iron to the solder underneath to melt it. You can try using your desoldering pump to pull up any loose solder but you may not get that much at this point. If you have solder on the board that’s not melting well, a trick is to melt new solder onto it, which helps conduct heat and will facilitate the old stuff melting.

Having a clamp or helping hands or other circuit board holder comes in handy. If you have one, clip your board in, and hold your soldering iron in one hand and your pliers in the other. Then melt the solder on each connection one at a time while rocking the component with your pliers from the other side of the board. In this way you should be able to gradually work the legs of the component out. If you don’t have a way of holding your board up, this won’t work, so your process will involve even more destruction of components, lots of crushing, twisting, and clipping stuff on the top of the board, then cleaning up the holes once the components have been removed. Finally, notice that the board of the Pi is covered with tiny components with labels next to them such as C97 or R24. These are capacitors and resistors, and you don’t want to break them off while you’re roughing up the components, so be mindful of where the capacitors and resistors are relative to each component you’re working on. And try not to scratch the circuit board either, as scratches too deep can mess it up.


The following pieces can be removed from your Pi:

1.) Ethernet port: it’s a big hunk of metal, so it draws away heat from the joints you’re trying to desolder. This will mean you have to hold the iron there a long time to melt those joints, and in the meantime your whole board is heating up; this can cause damage. So before you desolder, start inserting a little screwdriver or other thin prying tool into the seams on the metal Ethernet port casing and pry it open. Then remove the casing, which will leave the black plastic underneath. This can be desoldered and/or crushed with pliers.

2.) USB ports: unless you’re really skilled, you probably won’t be able to salvage these for later use, so remove the casing before trying to desolder them the same way you did the Ethernet port above. The plastic ports can be crushed a bit at a time and removed piece by piece.

3.) Camera and display ports: these are the two easiest parts to remove. They are surface mounted with many tiny pins, but don’t worry about desoldering each of them — just take your standard (not needlenose) pliers, grip each of the two ports, and twist them til they break off in pieces. Repeat til they’re completely gone. Use caution with the display board, because it’s on the other side of the SD card slot. It’s hard to accidentally damage the SD slot if you’re using the removal method I just described, but, you know, just in case.

4.) Headphone jack: this one’s not too tough, either. It’s got a metal casing you can pry off, then desolder and crush the plastic jack with pliers.


5) GPIO pins: the General Purpose Input/Output pins are the trickiest just because there’s so many of them and they’re so close to a bunch of tiny capacitors that are easy to accidentally break off of the
board. If you’re not able to easily desolder the bottoms of the pins from the underside of the board and just remove each pair of pins, which you should try first, you can do what I did: use your flush cutters to trim each pair of pins down as short as they can go, then you can try to break off the black plastic base of each pin pair with pliers or flush cutters. Under the black plastic base, you’ll find some more of the pin sticking up from the board, which you can trim down some more, then try again to desolder what’s left of the pins. Sudomod user IrieMars, in an excellent build log of a similar Wii U Pi project, suggested leaving two particular GPIO pins, labeled 2 and 6 in the diagram above, in your Pi rather than removing them, because you’re going to be soldering your power to these inputs and having the pins there instead of just the holes makes this process slightly easier. I recommend doing this too; trying using your pliers to remove the black plastic base from these pins, but then leaving them. You can also shorten the two remaining pins a bit by clipping off the top half of them with your flush cutters to save another few millimeters of space. In the above pic, you can see various stages of GPIO removal. I’ve cut off all pins but 2, 4, and 6 (4 went soon afterward, you don’t need it), pared down some of the pin bases, and cleaned some of the holes.

The truly hardcore could remove the HDMI port too; it doesn’t save you so much room off the Pi itself, but it would allow you to solder a flat ribbon cable directly the Pi for your video signal rather that using a cable with an HDMI connector, and you'll save some space that’d otherwise be taken up by the HDMI cable. It’s not really a job for beginners though, so I’m leaving the HDMI port in place. I’m also the leaving the micro-USB port in place, because it’s so thin that the trouble of removing it wouldn’t be worth the minimal space it would free up, and also so I can continue to use a 5V micro-USB wall charger to test the Pi at various stages of the build.

Once you’ve gotten the components off the board, you’ll still have some stray solder and metal component shrapnel in the holes and leaving this junk would mess up your Pi’s performance. So use your soldering iron to melt the remaining solder in the holes from one side while you use the desoldering pump and needlenose pliers to suck up the solder and pick up the metal shards. If you have soldering wick/braid, you can heat it up with your iron and rub it along the board to soak up any stray solder.


Here is my post-operative Pi.

Now that your Pi is slimmed down, you’ll want to test it to make sure it still works after all that abuse. If you’ve still got your HDMI and micro-USB ports, it’s simple to hook it up to a monitor and power and see if it boots. But since you’ll have no USB port, you won’t be able to properly shut down the Pi, so don’t put an SD card in the Pi with important data; unplugging the Pi without shutting it down properly can corrupt your data. A safer method suggested by IrieMars in this thread, which I will recommend and write a guide for soon, is to wire a new USB port (specifically, the one you’ll be using in your finished setup) to the Pi so you can hook a keyboard up and do a safe shutdown.

Some Further Component Preparation

I found that the battery holders I bought were a little taller than I needed them to be, and curved in at the top to ensure that the batteries don’t pop out. Since I am using protected cells, which are a few millimeters longer than unprotected, not only will they not fall out, but it’s almost impossible to get them out even when I want to, they’re wedged in there so bloody tightly. Also, the bit of unnecessary height kept me from closing the Wii U shell when I did a test assembly. So I clipped off a bit of the excess, leaving a shorter holder, as shown here.



You will also likely need to slim down the LCD board, just like you did for the Pi, I’m afraid, to remove the unnecessary stuff. Take off the three ports shown in the image below, but see the port that connects via ribbon to an external control board with buttons? Don't remove that port, just in case you need to do any setup/adjustments to the LCD after you install everything!

When desoldering the LCD board’s power port, note that the solder pads (the silver parts that each of the component’s pins are soldered to) are extremely delicate and can easily be damaged or pried off accidentally, which you don’t want. To prevent this, use care when you are clipping and prying, and don’t stick the tip of your soldering iron through the holes, which can push the soldering pads off.


What to remove and what to keep for now on your LCD board. Note the fragile soldering pads.

The headphone jack on the sound card has to go, so crush and desolder it. Then desolder the USB connector on the sound card as well, because you'll be soldering wires straight to the board later in that spot. Look at those teensy-weensy resistors and capacitors all over this thing; be careful that when you're heating up the USB connector to remove it, you don't melt the solder holding these little components, because if they fall off, they're a real pain to try to reconnect!

Shaving Down the Gamepad Interior

Ok, now it’s time to make some space inside the gamepad shell by shaving down the unnecessary plastic inside the back part of shell. Grab your rotary tool and grind down the parts indicated below. Again, thanks to IrieMars for the inspiration for this diagram; mine is very similar to the one posted on IrieMars’s thread.



You’ll be getting rid of the following pieces: six screw posts (three on each side), the big battery compartment in the middle (just grind through around the edges and the whole grid part will come right out), the stuff under the rumble assembly (above the battery compartment), and the five supports (two on the left, three on the right — two of the ones in the right are hidden in the picture, underneath the stylus holder). UPDATE [2/27/19]: Also, grind off the sixth, square support that is to the upper-left of the stylus holder, after peeling off the squishy foam; it's too chunky and needs to go.



When you’re done, it’ll look something like the above picture (UPDATE [2/27/19]: except this picture still has that square support that I later removed, and forgot to take a new picture afterward; see above). It looks pretty rough, but if you’re a perfectionist, you can make it nice and smooth if you want; I just didn’t see the need. You’ll see the part under where the rumble assembly was isn’t fully shaved down. I may have done so if I’d had a narrower rotary bit that can get in that little narrow area, but I’m not sure if doing so would save that much space, so I didn’t worry too much about it.

Installing Components (a work in progress)

It's time to start putting this thing together! Let’s install the screen first so you’ll know how much room you have to work with inside the rest of the case. The LCD I recommend for this project is ever so slightly too wide to fit in the raised frame inside the Wii U shell — see the photo below, and in case it’s hard to see the overhang, I added the dotted white line, which represents where the actual frame is, underneath the screen. We’re going to remove the plastic represented by that dotted line, so the LCD goes in, easy but snug.


Note that in this picture, the LCD is actually upside-down from the way it'll actually be installed, which is fine for my measurement purposes here.

The LCD is 89mm high, while the frame is 95mm high, so take an Exacto knife and mark a 3mm increment from the top and bottom corners of the frame on each side (or lay your screen down as I did in the photo and mark the edges, same difference), then use your rotary tool to grind down — or flush cutters to clip out — the space between the marks. Start from the middle and work out, so you don’t take off too much; ideally, your LCD will squeeze in there a bit tightly so it holds fast.


Here's what one side of your frame will look like after you've trimmed it.

But before you seat the LCD for good, clean the fingerprints and dust off of inside of the screen digitizer (the side that will lay against the LCD screen), then pop it into the Wii U shell, then put the LCD in on top (clean it off too). Note that the digitizer and monitor go upside-down from how you may expect them to go, with the ribbons coming out the top. If you get it upside down, you’ll notice it instantly; the screen and bezel won’t line up when you look at the front of the gamepad. For neatness's sake, if you want to cut off the ribbon that comes out of the digitizer, you probably can, as you likely won't need the touchscreen functionality for this project, but I'm keeping it intact, just in case.

At this point, you’ll want to make sure the back of your LCD screen is insulated so it won’t short your circuit. If you can see metal, cover it with an insulating layer. I cut a rectangle out of the thin plastic cover of a cheap composition notebook and just set it on the back of the LCD (no adhesive is required because the bracket assembly—see below—will hold it in place). If you got the same LCD that I did, your rectangle of plastic will need to be 9cm x 15.5cm.

The gray bracket that will hold the monitor assembly in place takes up a bit of unnecessary space and is a bit tight, so cut and/or grind the excess off; any supports or screwholes that protrude from the bracket can be removed. Then, making sure the ribbon connector for your monitor is exposed and accessible (thread it through the slot at the top of the bracket), screw the bracket in and enjoy having finished the easiest part of this build!



Now we’ll wire the joysticks. Take the two joystick assemblies and, on each, use pliers to crush the white plastic connector at the end of the wires, then pull out the five metal wire tips that will now be exposed. Peel your 10-lead ribbon wire in half a few inches so you have two bunches of five wires, then splice each bunch onto the five wires leading from one of the joysticks. If you don’t know how to splice wires, one simple method is outlined below.


Removing the connector tips from the joystick wires.

Cut off a 1/2 inch section of 1/32” heat-shrink tubing and slide it onto the first joystick wire you want to splice. Don’t forget this step! Next, separate each colored wired from the others by peeling down about an inch or so, then strip off about 1/4 inch of the rubber coating with your wire strippers, exposing the bare wire. Now wrap the exposed wire from your 10-lead cable tightly around the metal tip of the joystick wire, pull it to make sure it doesn’t separate (I’ve heard of people even putting some solder in the wrapped wire to reinforce it), then fold the junction you’ve created back along the wire, so it doesn’t stick out. Then slide the heat-shrink tubing over the junction so it completely covers the bare wire. Repeat this for the other four wires on this joystick and the five on the other joystick, then aim a heat gun at the heat-shrink tubing for several seconds til it shrinks tightly to the wire (but not so long it starts to melt the rubber coating on your wires).


Wrapping the first rainbow wire around the first joystick wire.


Don't forget to put heat-shrink tubing on each wire before you start wrapping them. If you forget, you have another chance later when you cut the other end of the rainbow wire, but I'm keeping it intact for now because I don't know how long it'll need to be.


This is what the wire wrap should look like; I've finished up the first wire, and am now about to pull the heat-shrink tubing down over the wrapped elements of the second wire.


Heat-shrink tubing over all the spliced wires.


The completed, shrunken splices.

When your joysticks are done, screw them back into place in the Wii U shell with those tri-wing screws. There we go!



Now put the upper face buttons (X, Y, A, B, +, and -) and the D-pad back in place, and put the conductive rubber backing over them; the buttons are cleverly engineered to make it very hard to mistakenly put them back in the wrong places. Finally, place the big white plastic casings over the buttons and joysticks on each side and screw them back into place. The larger single screwhole on the outer edge of each casing does not get a screw just yet (remember, they are used for the screws that hold the two halves of the Wii U shell together), but don’t forget the screwholes at the top of each casing, behind the L and R button conductors. And for good measure, you might as well slide the ZL and ZR triggers back into the button casing.



It’s time to start wiring the rest of it. I began with the micro-USB port and worked my way back through the circuit. There are five solder points leading from this component but you’ll only need to use the two power ones, labeled VCC (or sometimes 5V) and GRD, representing positive and negative, respectively. The other three are for data transfer (labeled D+ and D- usually) and device identification/specification (labeled ID); USB is so often used for applications that require these things, but we’re not using them here. I’m using 22 gauge wire (red for positive and black for negative, per common convention), and this wire turns out to be too thick to fit through the vias (solder holes) on this little board, but luckily the board came with lead pins. Stick them in, solder the underneath of the leads to the board (no need to solder the ID one and two data ones, I reckon) and then — don’t forget to position your heat-shrink tubing first — solder your black and red wires to the upright part of the leads and heat up the shrink tubing to finalize it.


The board with the lead pins stuck in, not soldered yet.

-----------------
EDIT (2/27/19): I have decided to move all subsequent steps into this post, rather than later in the thread, for convenience. Also, I have inserted mention of one more piece to grind off. And now I've added the first steps of assembly!

EDIT (7/29, 8/1, and 8/5/19): Added a few more prep steps, including how to prep the LCD board and the sound card.

EDIT (8/9/20): Added an insulating layer of plastic behind the LCD and updated pictures and instructions to reflect this.

[Ely]

Good job, keep going like this

[IrieMars]

Great work. Props for taking this on. It was a big pain in my ass to be honest but happy with the results. Don't forget the HDMI ribbon cable between the pie and your screed. One of my biggest regrets was not paying more attention to cable size and management. 26 Gauge is the way to go. Good look man, you're doing great so far.