Gameboy Retropie Portable

[therobopro]

OK. So I have been working on a GameBoy pi with my broken DMG- 001. I am almost done with my plans but I need help. I have been trying to get a audio configuration to work, I want to be able to have internal speakers AND headphones. I have a MAX 98306. Please help and POST COMMENTS PEOPLE!

[BMS Doug]

OK. So I have been working on a GameBoy pi with my broken DMG- 001. I am almost done with my plans but I need help. I have been trying to get a audio configuration to work, I want to be able to have internal speakers AND headphones. I have a MAX 98306. Please help and POST COMMENTS PEOPLE!

would a headphone socket with integral switch contact be suitable for this? When the headphones are plugged in they become the only audio output, when un-plugged the internal speakers are used.

I can't be sure but I think these 5 pin sockets may have an internal switch.

[therobopro]

I could be able to if I knew how to wire them. I was thinking of re using a gameboy one. The wires are left, right, GND, and bridged GND. Still working out bugs, but thank you!

[BMS Doug]

I could be able to if I knew how to wire them. I was thinking of re using a gameboy one. The wires are left, right, GND, and bridged GND. Still working out bugs, but thank you!

Umm, just re-read the Max 98306 learning materials and I don't think it can be used to drive headphones.

However, that means you cannot bridge R and L together, so don't try to connect ROUT to LOUT, it will damage the amp!

[BMS Doug]

I could be able to if I knew how to wire them. I was thinking of re using a gameboy one. The wires are left, right, GND, and bridged GND. Still working out bugs, but thank you!

Umm, just re-read the Max 98306 learning materials and I don't think it can be used to drive headphones.

However, that means you cannot bridge R and L together, so don't try to connect ROUT to LOUT, it will damage the amp!

You could use this as a mono amp, just driving both headphones from one channel of the audio output.

[Djinny]

I'm doing the exact same thing as the OP, if you salvage the original headphone jack, you can use it. it has an integral switch in it, meaning you plug the headphones in, and it would cut the ground going to the audio amp's speaker.

The switch is for the ground. So i've not tested it yet, but since the audio amp shares a common ground with the rest of the pi, i don't know if the audio's ground is the same.
If so, this won't work, and you'd need to find a switch that latches between the left or right speaker, and not the ground
I've included a little mockup of the dmg headphone jack, looking from the pcb side. It's just a quick mockup, but you can probably salvage yours the same way i did.. with a pair of wire snips.

I'm using these for my audio amps, you'll need to put a potemeter between the pi and the audio jack.
http://www.ebay.com/itm/371222637117

So the audio goes from the pi -> pot -> headphone jack -> audio amp -> speaker
where the right or left audio positive goes to the audio amp, and the audio amp's audio-ground goes to the Groundswitch listed in the picture.

PS: I'm also putting a pi2 in an original gameboy, with 640x480 3.5" screen, ps Vita joystick, and a bunch of extra buttons.
Keep in mind, if you want to make everything fit, you'd have to desolder a lot of stuff. i sure did. o_o

[therobopro]

I'm doing the exact same thing as the OP, if you salvage the original headphone jack, you can use it. it has an integral switch in it, meaning you plug the headphones in, and it would cut the ground going to the audio amp's speaker.

The switch is for the ground. So i've not tested it yet, but since the audio amp shares a common ground with the rest of the pi, i don't know if the audio's ground is the same.
If so, this won't work, and you'd need to find a switch that latches between the left or right speaker, and not the ground
I've included a little mockup of the dmg headphone jack, looking from the pcb side. It's just a quick mockup, but you can probably salvage yours the same way i did.. with a pair of wire snips.

I'm using these for my audio amps, you'll need to put a potemeter between the pi and the audio jack.
http://www.ebay.com/itm/371222637117

So the audio goes from the pi -> pot -> headphone jack -> audio amp -> speaker
where the right or left audio positive goes to the audio amp, and the audio amp's audio-ground goes to the Groundswitch listed in the picture.

PS: I'm also putting a pi2 in an original gameboy, with 640x480 3.5" screen, ps Vita joystick, and a bunch of extra buttons.
Keep in mind, if you want to make everything fit, you'd have to desolder a lot of stuff. i sure did. o_o

That is amazing ! I was thinking of using a 3ds joystick with a mcp3002 but I saw no need because I would only emulate up to SNES. I could not find a good way to have n64 controlls, if you are doing it can you post your control scheme? Thanks for the help!

Also keep posting comments guys!

[Djinny]

Long post, with lots of Links. When people ask me for help, i don't just link to other threads, I give all the infos. (I saw someone answer someone by linking to another thread.. but they linked to another post which actually linked to another post. This is not what we should expect from the famed raspberry pi community, we can do better, I will do better.)

I'm using the Teensy 2.0 arduino. Which will give me 23 buttons and 2 analog channels (1 joystick)
I had asked multiple times for help with using the mk_arcade gpio thing, but no one was able(willing) to help me. Here's my Teensy 2.0 code.
Which uses the arduino IDE. Just follow their directions, upload the code, and do some basic testing. It can be adapted to use more analog sticks in place of buttons.

I was going to use the exact same ADC too, but decided to go the teensy route and save myself the hassle.
Here's some of what i got so far. I'll add more pictures regularly and will likely put a full post here on the forums once i'm done.
http://imgur.com/a/lhY1x

Using an expensive 3.5" 640x480 LCD and an hdmi to vga adapter. I'll be done with the whole project in a couple days.
I would suggest using a psp 1000 slide-joystick instead. it doesn't tilt, but it does slide around, and they are fairly flat, and can fit inbetween the AB/Dpad buttons. Right above start select.
A PSP 1000 joystick will be WAY easier to install, 4 wires, big fat pads to solder to.
I desoldered almost all the headers on the pi2, except the usb power, since that is a non issue. You can see how little it gets. I then soldered 30awg kynar wire for the hdmi (commonly referred to as Mod Wire). I messed up the Camera header desolder, got frustrated and ripped off a few pads.
No matter how hot i got it, the solder refused to melt.

If you do use the ps Vita joystick, this will help, you can get some free connector samples from molex.com
If you get some 6pin/0.5mm pitch FPC headers from molex (if you need part numbers, let me know)
you can solder the headers to a Breakout Board.
If i ever use another vita joystick in a build, i'm SOOO going for the breakout boards, i handsoldered the connector to a small piece of flex cable from another scrap salvage, i ended up missing a +v pin, but just soldered the 3 pins together on the ps Vita joystick. They need to be linked anyways so it worked.
Keep in mind, Soldering to the hdmi, or even to some 6 pin connectors for a PS vita joystick.. is not easy, it's 0.5mm pitch width, Which is VERY hard to hand solder to.

I decided to use http://store.kitsch-bent.com/product/co ... button-pcb
but i could have went with the original board snipped down. But i wanted cleaner contacts for better controls.

I went with the expensive LCD, which cost $111, because i wanted 640x480, not some blurry 320x240. I made an offer of $111, to match another seller's price, since i wanted to buy from this seller specifically. They packed it really well.

I decided not to use the original gameboy's audio jack, and i'm using one i salvaged off an old laptop motherboard. The gameboy has a groundswitch, which may cause issues, and i don't want to risk it, so i'm using the laptops, with uses a left-channel switch instead. so the ground will be active, but it'll cut the audio to the left channel.

I'm going to use a 4000mAh 3.7v lipo, and a 500mAh charger and 1A* boost converter. The converter is rated for 1A but adafruit says it had no trouble going up to 2A.
I would strongly suggest using a 1A charger. I'll likely upgrade in the future. Alternative: Fancier 1A charger, not sure what makes it better. At 500mA charge rate, my battery took too long to charge.

Using a PSP 1000's speaker. It's the size of a dime, which is nothing, and it should get loud enough with a good resonance shroud.

Buttons i'll be using connected to the teensy.
4:Dpad
2: A/B
4: C-up/left-right-down(n64)
2:Start/select
4: Quick save, quick load, Menu, and Esc(exit emulator.)
4:Left trigger, RT, Z(n64), Turbo toggle,

1 Joystick(2 analog channels)
That's why i'm going with the teensy 2.0, which cost about $20 shipped. LOTs of buttons, and built in ADCs, connect it to the pi with USB, and it'll register as a usb gamepad. (i've already confirmed it working)

Tips: When working with FPC/Flex cables, use some wide clear packing tape, and Ghetto-laminate the flex cables. Just up to the connector. The flex cable on the LCD i linked, as well as the one on the PS Vita joystick are both incredibly fragile, so put tape on both sides and CAREFULLY trim it so it's about 3-4mm off the edge of the flex cable. This will make them considerably stronger since they can tear so easily. This also works for nintendo DS flex cables, which are fragile like tracing paper.
To solder the 6pin ps vita connector to the breakout board, use a hot air rework tool and Kapton tape (special tape that can withstand up to 400c)

[therobopro]

Long post, with lots of Links. When people ask me for help, i don't just link to other threads, I give all the infos. (I saw someone answer someone by linking to another thread.. but they linked to another post which actually linked to another post. This is not what we should expect from the famed raspberry pi community, we can do better, I will do better.)

I'm using the Teensy 2.0 arduino. Which will give me 23 buttons and 2 analog channels (1 joystick)
I had asked multiple times for help with using the mk_arcade gpio thing, but no one was able(willing) to help me. Here's my Teensy 2.0 code.
Which uses the arduino IDE. Just follow their directions, upload the code, and do some basic testing. It can be adapted to use more analog sticks in place of buttons.

I was going to use the exact same ADC too, but decided to go the teensy route and save myself the hassle.
Here's some of what i got so far. I'll add more pictures regularly and will likely put a full post here on the forums once i'm done.
http://imgur.com/a/lhY1x

Using an expensive 3.5" 640x480 LCD and an hdmi to vga adapter. I'll be done with the whole project in a couple days.
I would suggest using a psp 1000 slide-joystick instead. it doesn't tilt, but it does slide around, and they are fairly flat, and can fit inbetween the AB/Dpad buttons. Right above start select.
A PSP 1000 joystick will be WAY easier to install, 4 wires, big fat pads to solder to.
I desoldered almost all the headers on the pi2, except the usb power, since that is a non issue. You can see how little it gets. I then soldered 30awg kynar wire for the hdmi (commonly referred to as Mod Wire). I messed up the Camera header desolder, got frustrated and ripped off a few pads.
No matter how hot i got it, the solder refused to melt.

If you do use the ps Vita joystick, this will help, you can get some free connector samples from molex.com
If you get some 6pin/0.5mm pitch FPC headers from molex (if you need part numbers, let me know)
you can solder the headers to a Breakout Board.
If i ever use another vita joystick in a build, i'm SOOO going for the breakout boards, i handsoldered the connector to a small piece of flex cable from another scrap salvage, i ended up missing a +v pin, but just soldered the 3 pins together on the ps Vita joystick. They need to be linked anyways so it worked.
Keep in mind, Soldering to the hdmi, or even to some 6 pin connectors for a PS vita joystick.. is not easy, it's 0.5mm pitch width, Which is VERY hard to hand solder to.

I decided to use http://store.kitsch-bent.com/product/co ... button-pcb
but i could have went with the original board snipped down. But i wanted cleaner contacts for better controls.

I went with the expensive LCD, which cost $111, because i wanted 640x480, not some blurry 320x240. I made an offer of $111, to match another seller's price, since i wanted to buy from this seller specifically. They packed it really well.

I decided not to use the original gameboy's audio jack, and i'm using one i salvaged off an old laptop motherboard. The gameboy has a groundswitch, which may cause issues, and i don't want to risk it, so i'm using the laptops, with uses a left-channel switch instead. so the ground will be active, but it'll cut the audio to the left channel.

I'm going to use a 4000mAh 3.7v lipo, and a 500mAh charger and 1A* boost converter. The converter is rated for 1A but adafruit says it had no trouble going up to 2A.
I would strongly suggest using a 1A charger. I'll likely upgrade in the future. Alternative: Fancier 1A charger, not sure what makes it better. At 500mA charge rate, my battery took too long to charge.

Using a PSP 1000's speaker. It's the size of a dime, which is nothing, and it should get loud enough with a good resonance shroud.

Buttons i'll be using connected to the teensy.
4:Dpad
2: A/B
4: C-up/left-right-down(n64)
2:Start/select
4: Quick save, quick load, Menu, and Esc(exit emulator.)
4:Left trigger, RT, Z(n64), Turbo toggle,

1 Joystick(2 analog channels)
That's why i'm going with the teensy 2.0, which cost about $20 shipped. LOTs of buttons, and built in ADCs, connect it to the pi with USB, and it'll register as a usb gamepad. (i've already confirmed it working)

Tips: When working with FPC/Flex cables, use some wide clear packing tape, and Ghetto-laminate the flex cables. Just up to the connector. The flex cable on the LCD i linked, as well as the one on the PS Vita joystick are both incredibly fragile, so put tape on both sides and CAREFULLY trim it so it's about 3-4mm off the edge of the flex cable. This will make them considerably stronger since they can tear so easily. This also works for nintendo DS flex cables, which are fragile like tracing paper.
To solder the 6pin ps vita connector to the breakout board, use a hot air rework tool and Kapton tape (special tape that can withstand up to 400c)

Wow!!! Long post is right, but I thank you for doing it with lots of info. Anyway that battery looks promising! Its dimensions are 3.740" x 2.204" so it is small enough. What I will be doing is making a custom PCB with these buttons.

http://m.ebay.com/itm/PKG15-Tactile-Pus ... 0659489028

I want to have a common GND for it because I will be using a raspberry pi GPIO header for my inputs. The screen you have is awesome but unfortunately I am on a budget build, and do not have the money, but WOW that screen is SHARP.
Thanks for your help!! And keep posting comments guys!!!

P.S if you have zl and zr you can play PS1 on your portable. I think one more button is worth it!

[Djinny]

Wow!!! Long post is right, but I thank you for doing it with lots of info. Anyway that battery looks promising! Its dimensions are 3.740" x 2.204" so it is small enough. What I will be doing is making a custom PCB with these buttons.

http://m.ebay.com/itm/PKG15-Tactile-Pus ... 0659489028

I want to have a common GND for it because I will be using a raspberry pi GPIO header for my inputs. The screen you have is awesome but unfortunately I am on a budget build, and do not have the money, but WOW that screen is SHARP.
Thanks for your help!! And keep posting comments guys!!!

P.S if you have zl and zr you can play PS1 on your portable. I think one more button is worth it!

Wow you quoted my whole post. XD a -snip- might be in order.
The Turbo button will be opposite of the Z button, which will be configured in the emulator, since PS1 isn't the smoothest to emulate, it won't be receiving turbo, and will instead act as the R2(ZR).

Oh, it isn't the easiest, but you can use the original gameboy's front motherboard, score it, and snap it down to size and use it as a common ground board.
AB buttons, http://i.imgur.com/ZvcO1fc.jpg
Dpad and St/Sl, http://i.imgur.com/smSvCJ9.jpg http://i.imgur.com/gkWTCh0.jpg
It isn't pretty, but it works, if you keep the whole thing connected it'll work, just use a razor to snip and rip of unwanted traces. 30awg kynar/mod wire is a must have for this.
I just wanted the pretty black Common ground board i linked earlier. Controls are super important, so they have to be responsive and quick. Using the gameboy's original dpad and AB buttons are kind of important.

[therobopro]

Wow you quoted my whole post. XD a -snip- might be in order.
The Turbo button will be opposite of the Z button, which will be configured in the emulator, since PS1 isn't the smoothest to emulate, it won't be receiving turbo, and will instead act as the R2(ZR).

Oh, it isn't the easiest, but you can use the original gameboy's front motherboard, score it, and snap it down to size and use it as a common ground board.
AB buttons, http://i.imgur.com/ZvcO1fc.jpg
Dpad and St/Sl, http://i.imgur.com/smSvCJ9.jpg http://i.imgur.com/gkWTCh0.jpg
It isn't pretty, but it works, if you keep the whole thing connected it'll work, just use a razor to snip and rip of unwanted traces. 30awg kynar/mod wire is a must have for this.
I just wanted the pretty black Common ground board i linked earlier. Controls are super important, so they have to be responsive and quick. Using the gameboy's original dpad and AB buttons are kind of important.

Hmm. I was wondering where to solder the wire to the start/ select, I was going to salvage them since there is no way to make the same buttons with tactile switches. Since I am only emulating up to SNES, is there a way to combine two gameboy PCBs to make ABXY? I still have the original gameboy PCB from when I took it out of the DMG-001 case. Maybe I could attach A and B to a common ground button PCB from kitsch, and have l and r separate. What do you think? Also thanks for your help. Keep on submitting comments everyone!!!

[Djinny]

Hmm. I was wondering where to solder the wire to the start/ select, I was going to salvage them since there is no way to make the same buttons with tactile switches. Since I am only emulating up to SNES, is there a way to combine two gameboy PCBs to make ABXY? I still have the original gameboy PCB from when I took it out of the DMG-001 case. Maybe I could attach A and B to a common ground button PCB from kitsch, and have l and r separate. What do you think? Also thanks for your help. Keep on submitting comments everyone!!!

Alright if you look at the huge image of the AB board i snipped. At the bottom there's the blue wire (blue wires are ground for my project)
It comes in through back of the through-hole on the bottom left of the board, and then connects to the lower "pads" of the other button, so both buttons share a common ground.
The lower red wire goes to the pad on the left of the image, the other red wire goes to the right.
Most of your controls will be A/B and Dpad, Sand paper will clean the solder mask off the traces, and a smidgen of flux will let you solder to the pads cleanly. So the AB board shares a common ground.

As for the lesser used C/XYZ buttons, tactile buttons are fine. Most RPGs have those for opening menus and such.
The Dpad/Start/select board that i made, in the top left of the board, you can see a ripped up part of the trace that goes to the D-left, then soldered a ground wire to the 4 pins for the Dpad, so the Dpad all shares a common ground. I then ripped up traces on the bottom of the board, so the D-Left connects on that lower-left red wire. The blue wire on the bottom right is the common ground for the start select. which i just brought up to the other blue wire, so i only had 1 ground coming off it.
So both boards have a common ground for all the buttons.
Had i kept the 2 boards together, i could have made it much cleaner. I just thought it was ugly the way i had done it, even though it works, so i went with that black-common-ground board from the earlier post. because aesthetics mean a lot to me.

30 awg solid core kynar mod wire, get this stuff, it's freakin amazing. It solders very well, and 2 wires directly next to eachother, is 0.5mm pitch width.
When building stuff, you need to take into consideration the size of your wires, but if all your signal wires use the kynar wire, if you do it nicely, it takes up very little space.

[therobopro]

OK. So which one do you think will play better, the PCB board with tactile switches, or the black board you talked about with extra gameboy ab buttons for X and Y? Also that wire you used looks nice and I will get some. Thanks for your help and keep posting comments!!!

[Djinny]

The black board is really nice, soldering the ground wire is a bit tough since it has a huge ground plain that works like a heatsink but turn your iron up and it'll work fine.
It feels good and the contacts are tighter and gold plated which would be better for controls.
But, it's also kind of expensive, looking at about $17usd with priority shipping($6.50) vs standard shipping ($5), it's 2days vs 1-2 weeks.
I'm using the black board with little tactile buttons for other stuff, i'll mostly be playing n64 and gameboy games which mostly use the A/B buttons. Keep in mind, space is always an issue. You did not start an easy project. I've got a decent budget, so i can choose the nicer bits. But it's still a bit of a stressful project.

[therobopro]

OK. So I forgot to ask you, on the audio wiring diagram from here http://www.xodustech.com/projects/raspb ... boy-pocket what are the white and red wires that connect to the pi audio and where to put them on the pi 2. Thanks for your help and keep posting comments!

[therobopro]

Also, for your project, I want to suggest this http://www.thingiverse.com/thing:707612

[Djinny]

OK. So I forgot to ask you, on the audio wiring diagram from here http://www.xodustech.com/projects/raspb ... boy-pocket what are the white and red wires that connect to the pi audio and where to put them on the pi 2. Thanks for your help and keep posting comments!

Left and Right audio, Left is white i believe. Since it uses a common ground. Sadly i don't think you'll be able to use the integral switch of the original gameboy's headphone jack since it's a ground switch, and you'd want a Left-switch.

I don't have a 3D printer, i just "finished" my build. I still have a lot of tweaking.

[therobopro]

OK. So I forgot to ask you, on the audio wiring diagram from here http://www.xodustech.com/projects/raspb ... boy-pocket what are the white and red wires that connect to the pi audio and where to put them on the pi 2. Thanks for your help and keep posting comments!

Left and Right audio, Left is white i believe. Since it uses a common ground. Sadly i don't think you'll be able to use the integral switch of the original gameboy's headphone jack since it's a ground switch, and you'd want a Left-switch.

I don't have a 3D printer, i just "finished" my build. I still have a lot of tweaking.

Can you show me a list of the components that you used for your audio and the points that you soldered on the rpi

BTW Thanks For Your Help Djinny!!!

[Djinny]

Sadly i cannot, i'm using an HDMI to VGA converter that has Audio out. I removed the headers and sockets from my rpi2, as well as from the HDMI-VGA converter. And i found that using the audio directly from the pi's 3.5mm jack points just wasn't very good for me, it caused... issues. the sound wasn't very good, so i rerouted those wires to the audio points on my hdmi converter and set the rpi's config and the retropie's config to use HDMI. this cleaned up the sound a lot.

I'm using a small pot (which isn't wired right, i'm just too lazy to fix it) which can drop the external volume to half. my earbuds have a volume slider so i can adjust the volume there.
but the audio goes from the HDMI converter -> The stereo headphone jack -> Left channel goes to the pot, which then goes to the mini 3watt audio amp, which then goes to 2 PSP 1000 speakers. the L+R inputs on the audio amp are bridged, so i get left channel out of both, my headphone jack doesn't have an integral right channel. But if you use the gameboy's original headphone jack, you can use it's integral-ground, to cut the ground entirely to the audio amp. Would save power and would work perfectly (i intend to do this eventually.)

Not sure if this helps or not.

[bucker]

Hey Djinny i'm following your post and learning so much, thank you

i'm also building a portable gaming system based no RPi but inside a Wii U gamepad case, can you please point me the best way to solder the original gamepad board to RPi GPIO? here are the pictures:

here is the strip: http://s27.postimg.org/6v4gmhc43/IMG_0325.jpg

can i solder this directly to GPIO, or i need additional stuff?

i'm very noob on this so sorry if i'm asking a stupid question

[Djinny]

I don't really know the pinout of the flex cable. and the picture isn't quite suitable for me to give you a trace..

But, first thing's first... find out which half of each button pad goes to which flex cable "pin", you may find that they have a common ground, or maybe they don't, i can't tell from the image. If they do, great, if not, then you may need to make an artificial common ground between all the pads, which will go to your pi's ground. Then the other half of the pads will link to your gpios, so when you press the button, it'll pull that gpio down to ground. you CAN solder the lines directly to the gpios, but i'd suggest using a flex ribbon cable connector, get the number of pins, and the pitch width (distance between pins) and either get the connector from either ebay, or molex.com or something.

That way you can disconnect the pi from the game pad without needing to desolder anything.

Before you start soldering anything, i suggest making what i call a ghetto-gamepad to make sure all the GPIOs and your programs are working.
I made this one for my gameboy when i was considering the GPIOs before i decided to move to the teensy 2.0. (The teensy 2.0 acting as a joystick saved me a LOT of time and frustration, since it was very straight forward)
http://i.imgur.com/23Juofd.jpg
http://i.imgur.com/DBSdyio.jpg (a bit blurry, damn crappy camera)

Always test on some left over junk before you put your build together. And if you think you can get away without testing, remember that this says otherwise. http://i.imgur.com/sm8L82v.png

[bucker]

well, definitely i need to learn a lot before start assembling everything together, btw, do you have some pictures of your project?

Actually i already bought some FPC connector that hopefully will play well with the ribbon cable, here's the link

http://www.ebay.com/itm/191308750571?_t ... EBIDX%3AIT

but i'd suggest using a flex ribbon cable connector, get the number of pins, and the pitch width (distance between pins) and either get the connector from either ebay, or molex.com or something.

That way you can disconnect the pi from the game pad without needing to desolder anything.

(sry again but i need to ask this lol) but even with the FPC connector, what's the best way to wire this to the Rpi's GPIO? just straight solder the end of the connector to a female connector on the Pi's end?

[Djinny]

I can't help with that last bit, the best way for me, may not be the best way for you. If you intend on removing the pi later, using headers would be easier, if size is an issue, using an old IDE ribbon cable could help get the wires at 90 degrees as opposed to straight up and down. Because of the space of my gameboy, i didn't have a lot of space to work with, so i ended up removing all the headers except the usb power, since it wasn't in my way. Which left me with a very flat, very thin board. But it was also a pain in the back side. You can also use snips to shorten the gpio pins if they get in the way, but i figure the usb/network will dictate your height requirements.

http://imgur.com/a/lhY1x

That said...
IF i was going to make a Wii-U pi-boy thing. I'd use a teensy 2.0 for the controls, just because it's easier.
There's enough space inside for a massive battery, 6000+mAh, along with a 1A+ charger, i've not found a 2amp lipo charger module yet, but it would be nice.
I'd use a really bright IPS high res screen, even if it meant trimming some of the plastic. A 6" screen with higher than original resolution is possible. The wii-U controller's base res is 854 x 480. I'd try to find something double that. Personal preference.
I'd remove the USB/Network/GPIO headers, and maybe the analog A/V, but keep the HDMI and power, get it nice and short, to give me more room for the battery. Removing the headers is a HUGE pain, i had to use a hot air rework station, and i still lifted a couple pads of the camera zif connector, but i knew i'd NEVER attach a camera to it, so it didn't bother me that much.
I'd use a tiny 5v blower style fan like in my gameboy, with a transistor and hardware PWM, the pi doesn't need cooling, but lipo batteries don't like heat.. also if it gets warm, it'll get uncomfortable.

I'd keep the camera and try to configure it as a usb camera. I'd add a mini wifi dongle on with a switch going between the 5v and the 5v source, i use the EDIMAX-EW7811Un, with a mini power switch, just to save on power. If you don't use wifi, just reroute the network connector to the edge of the case so you can connect externally, not something i would do. but it is an option.
Bluetooth optional. And i'd make sure to have 1 external usb port. I don't have bluetooth in mine, because it's not a big deal. if i needed bluetooth i could plug a dongle into the side of the gameboy.

[bucker]

Impressive work on the Gameboy mate.

These are the parts i'll be using for start:

- 7" HD 720p screen (yeah, will have to trim the case a bit)
- 4x 18650 high capacity batteries (8800 mah each)
- Dual USB 5V 1A 2A Mobile Power Charger power board module 3.7V to 5V booster (to power the screen and the Pi)
- Mini 2.5-5V 2X3W Audio Class D Amplifier Board (i'm using the pad's original speakers)

i'm still waiting for the items to arrive, as soon as i get it i'll be posting some pictures here or in a new thread.

thank you so much for the help.

[Djinny]

Curious how you have the chargers and power connected. i don't believe they can be connected in parallel.
using 2x 3.7v->5v boosters is a non issue especially if they have a disable pin (brings power consumption to like 20µA "micro-amps" when the disable/enable pin is pulled to ground.)
But using 2x 1A chargers could be an issue, since i'm assuming you have the batteries in parallel too. The supply voltage of charger1 would make the charger2 turn off because it thinks the battery is charged, since it's receiving 4.2v from charger1

I haven't found a normal 2A lithium battery charging module for li-ion or lipo batteries. At least not small enough for projects.

For my power power, i use 2 power switches, a 2position 3pin power source switch, and a 2position, 6pin on/off switch.
The power source switch i use, selects if the power is running off external, or battery, So External-powerswitch-booster on the first switch, so it links either the booster to the power switch, or the external power to the power switch. (external power always feeds to the charging module as well.)
The On/Off switch, has 6 pins, both rows are not connected.
1-2-3 (2, center, goes to the power select switch, and 3 connects to the pi.)
4-5-6 (4 goes to the booster's enable pin, 5 goes to ground)
So when moved right, 2-3 are connected that supply the pi with 5v, and 4-5 are disconnected which takes the boost module out of standby.
when left (off), 2 is floating, pi receives zero power. and 4-5 are connected, which grounds the enable pin which brings the booster module into power save mode.... so it doesn't drain my battery when it isn't plugged in.

I wanted a 3position 6 pin switch, but couldn't find one that i could put confidence in. AKA on/off/on
1-2-3 (so 1/4 would link the pi to the booster, 2/5 from ground to enable pin, 3/6 to link pi to the external power.)
4-5-6
So i just went with a 2 switch solution. Now i just need to find a way to switch from external to battery without it turning off the pi. Since the split second it's off, resets the pi, and my pi consumes more power than my charger puts out, so i can't just run off the battery all the time.