Pi in a Gameboy Advance Build - WIP

moosepr

@obsidianspider there are a few different i2s boards that are designed for stereo output, there is a little bit of a craze for making audio players from pi's. The apparently give good sound quality, but I have never listened to one so i can't comment.

The main problem is that they are not designed to be small, and are not really all that cheap either.

Most are designed for the larger pi's like this
http://www.iqaudio.co.uk/audio/8-pi-dac-0712411999650.html
Which would actually work with the zero, just not fit inside your case! There are smaller ones designed for the zero
https://shop.pimoroni.com/products/phat-dac
But again, that will make space an issue

There is also a plan c that I'm not sure if it will work. But looking at the tiny adafruit i2s doohickey, you can actually tweak the device to do just the left or just the right channels. Now I'm my limited understating of i2s is that it is quite one sided communication, so it may be possible to wire one in for each channel to get stereo sound.

I have had a thought though, how many of the games that can run on a zero, have actual stereo audio?

cyperghost

@moosepr said in Pi in a Gameboy Advance Build:

There is also a plan c that I'm not sure if it will work. But looking at the tiny adafruit i2s doohickey, you can actually tweak the device to do just the left or just the right channels. Now I'm my limited understating of i2s is that it is quite one sided communication, so it may be possible to wire one in for each channel to get stereo sound.

That's possible imho (I haven't tried) but the small adafruit amp is designed for seperate channel so using two of these should work. As I often said... These little boards may be a good choice for the Pi0. I think HDMI splitters are not cheap - also a good (and cheap) solution is use of a USB sound card (with the HUB thing).

But it's a manifest .... If you are in need for GPIO wiring to get sound then rather use I2S than PWM.

there are a few different i2s boards that are designed for stereo output, there is a little bit of a craze for making audio players from pi's. The apparently give good sound quality, but I have never listened to one so i can't comment.

Yes that's the point why I2S may net be used so often. Hifiberry and Phatdac are knowen solution but they are big in size and well... the costs are high. Of course they are designed for stereo output - the I2S system is common in every CD player. I also think they need a lot of more wires to work. Some use the I2C bus to get volume control. And some use I2S just as converter and need a separate AMP. So the little adafruit is just cool :) and the prizing is more than acceptable :)

I have had a thought though, how many of the games that can run on a zero, have actual stereo audio?

Some Mame games and some SNES games. Moreover PSX is very common and well N64 and PSP (but +Pi0=automaticfail). I think in 85% it doesn't matter if it's mono or stereo. But what I can say is that the adafruit I2S amp gots a excellent and powerfull sound output!

diegzumillo

Hey there
Just to add some more comments to my quoted comment up there. There was a topic at adafruit's forum where they explained their powerboost 1000's limitations. If I remember their words it was something like "the pi 2 is already stretching what the powerboost is capable of but it's not meant for pi 3". Those were not the exact words but the idea is that it actually works on the pi 2, if you need more performance than the pi zero. "Stretching" to me means it works.

cyperghost

@diegzumillo
Sorry, I didn't get you :D

obsidianspider

The broken DS Lite I bought on eBay showed up today.

Using two guides over at iFixit I had the DS Lite apart in minutes. If I was actually trying to put it back together again I could see it taking much longer.

I'm mainly concerned with the ABXY button area and that part of the circuit board, but I've read that the DS Lite speakers sound pretty good, so hopefully these aren't blown. It also had the 1000mAh 3.7V battery inside, so I may mess around with that a bit during my initial testing of going on battery power.

It looks like I'll be able to section out the ABXY area of the case and frankencase it into the GBA case

I took a piece of scrap paper and did a rubbing of the button holes from the DS Lite and placed it on the GBA case and it is like it was made for it.

Next I'm going to see if I can wire up the ABXY buttons from the DS Lite and the directional, L, R, Start, and Select buttons from the GBA. I found some pinouts on a few different websites.

0_1478728954020_dslight pinout.jpg

With how thin the DS casing is I'm thinking I will be able to put the DS Lite PCB on top of the GBA PCB and that extra depth should make up the difference in case thickness. At least that's the theory.

Onward.

moosepr

@obsidianspider looking good dude! I did think those nds buttons would be a good fit for the GBA

obsidianspider

@moosepr The trick now will be to modify the case and not have it come out looking horrible. First though, I'll tackle the buttons. There are a ton of resistors, capacitors and ICs on the back and I want to cut the button pad area down pretty hard, but I also don't want to wreck a trace.

moosepr

@obsidianspider yeah that was always my worry. the texture on the GBA is a nice and smooth, but with an obvious texture. there are some online that have the whole 'sucked toffee' look to them, and loose the whole 'factory finish' there are of course ways to get texture. There are even the totally random stone effect paints that could actually be that weird kind of cool

obsidianspider

Today I decided to start working on getting the boards trimmed down. First I desoldered all of the "stuff" that I wouldn't be using (capacitors, resistors, ICs) from the PCBs. Some didn't go very well, but I really only care about the button pads for the most part.

Then I cut things down with my Dremel.

A test fit shows that things look pretty good.

I was hoping to reuse the red, green, and orange LEDs from the DS Lite for power, low battery, and charging, but it looks like the green LED is burned out. Oh well, I'm definitely already getting my $7 worth out of the unit.

obsidianspider

To anyone who thinks this stuff is easy, it's not. I've been frustrated with this project the past few days. The whole "fit ten pounds of stuff in a five pound bag" is becoming very real. I ordered a volume potentiometer, but just discovered the factory headphone jack isn't going to work how I need it to, so I'm back to figuring that out. The fun is in figuring it out, but sometimes it's not as easy as others.

moosepr

@obsidianspider I was actually thinking the same on my handheld build. Even though I wasn't squeezing stuff into a case, I still had problems to solve. I might even go as far as to say that I enjoyed making it, more than I enjoy playing the games on it!

obsidianspider

@moosepr The volume wheel showed up today, but I'm still kind of burnt out. That said, I also ordered a USB hub with a built-in ethernet switch and I put a Pi Zero in there today to act as a Pi-Hole server. It was a good learning experience of fitting small things in a case together.

It went OK. Not as perfectly as I would have liked (I had to remove a USB port to get it to close), but it worked. It's powered by the USB plug via a USB port on my router and the ethernet plugs back into the router. No external power supply. :)

edmaul69

@obsidianspider thanks for the extensive guide. I have two of these screens i bought quite a while ago. I was able to get them to run raspbian on them but not retropie. At the time everything i read said they wouldnt work on retropie. So ive just held onto them and am planning on doing a handheld sometime soon.

edmaul69

@obsidianspider on my pi zeros i use a rockband usb hub that has 4 ports in a row but does not use a power brick. Dont buy the one with three hubs in the front and one in the back. There is a powered 4 in a row rockband hub that you dont want. The one you want says 4 port hub.... all on one line on the top of it.

obsidianspider

@edmaul69 One reason I went with the 3.2 over the 2.8 (which would probably fit better) is because of the support for it. The 2.8 can work, but the 3.2 has a higher refresh rate.

moosepr

@obsidianspider how's the case chopping going dude?

obsidianspider

@moosepr I've had a lot going on the past week or so, and I wasn't able to give the project any attention.

This weekend I'm going to work on the audio circuitry so I can see how that's going to fit. I am probably going to need a different headphone jack along with the new volume wheel I got, and I need to determine where everything is going to go inside the case before i start cutting away at the outside.

obsidianspider

It's been a pretty productive morning. I won't be able to use the stock Gameboy Advance headphone jack because of how it's set up (it doesn't have an output, just a trigger for the GBA amp to switch to the speaker) so I ordered some headphone jacks from China that will be here in a few weeks. I also ordered a power strip PCB and it was incredibly cheap. Now I see why people start messing with custom PCBs…

I also ordered a micro USB breakout, a PowerBoost 1000c, and a 2500mAh battery to see about cramming that stuff in. I think this is going to work. The plan right now is to put the audio circuitry on one side and all of the power "stuff" on the other, with the Zero and battery behind the screen, and micro USB charging in the place where the stock GBA communication port is and a USB A connector (or two? maybe put the USB hub at the top?) in the GBA game that I bought so I can plug in a keyboard or whatever. I still have to see about the best placement for the USB hub, but I'll have a better idea on that once the battery and PowerBoost arrive.

jb32647

@diegzumillo That's interesting, I saw someone make a Pi3 handheld, and according to his parts list, he used a powerboost 1000c. On the video it seemed to work fine so maybe it's a bit hit and miss.

diegzumillo

@jb32647
I might have seen that same video. I even asked him about it and he confirmed it was a pi 3 with a powerboost 1000. I really don't know what to make of that either. I tested it myself and it doesn't work, the Adafruit technicians confirmed it doesn't work. Maybe he had a pi2 instead and didn't know? they look the same.