Need some advice about audio (...and maybe general build advice.) Help save our build!

[BowmarDafty]

I am building a gameboy zero as part of a youth work program and we are all going in pretty blind. We need some help on putting together the audio aspect of the build. Does anyone have any advice?

I initially started looking at Wermy's build on the Sudomod forums and found a "UK Parts list" that I used to get all the parts we needed. Then began to realise that the parts were different in that list to the 2 builds that he had on the site. Not a problem, there are many builds so we powered on... we're kinda stumped with the audio stuff. Too many different builds... not sure what to do with the parts that we have.

I'm going to put a list of every part we got just for clarity...

Aftermarket case (standard, no internal board)
Button PCB (just buttons, no other inbuilt components)
Button Pads
Speaker (replacement nintendo gameboy speaker.)
Screen (screen and board already hooked up to the Pi Zero and working)
2500 mAh Lithium Ion Polymer Battery
micro USB breakout board
9mm Tactile Switches
Volume Wheel
PJ325 headphone jack
PAM8302 2.5W Class D Single Channel Audio Amplifier Board Amp Module AM
USB Hub
5V USB Powered PCM2704 MINI USB Sound Card DAC decoder board
I've left out a lot of the cables, solder, Pi Zero stuff for the sake of sanity.

What we have already done (though are willing to undo if need be!) is wire and solder the Pi Zero to the Screen (working) and the button PCB board. (untested - based off of this map-> viewtopic.php?t=5252 )

We're struggling to find info or a map on how to set up audio without an original GB board to modify or an "all in one board". Is this even possible?!

Thanks for reading all this is you have. Myself and everyone involved with this build would hugely appreciate any advice or guidance with this.

Also, if you notice anything important that we may be missing then give me a heads up haha

[infinitLoop]

others have more experience than me, but i've done the three main ways so far in my builds and tests, so here's my thoughts...

i've tried the pwm audio (like in wermy's original) a few times, but the best sound i ever got from that was not great - hissy and quiet and hard to get a good range in the volume wheel without it just distoring or cutting out, and the amp placement was definitely confusing- i tried it in the different ways people said they did it, but haven't been satisfied with any of the results yet. you also have to wire or buy the filter, which is a bit of a pain.

usb audio sounds good, and wiring is relatively easy- four wires, but means disassembling a audio adapter, removing stuff, and possibly breaking it in the process. and it takes up a usb port, so you need the hub if you want to keep an external port - which you do have on your list already, but those parts can take up space in the build, that runs out quicker than you expect - and you need the amp to boost it for the speaker, although some people say they get by with just the headphone jack amp. however, not having to do the hub and audio and amp is nice, since...

in my opinion, the i2s audio sounds the best, and seems pretty easy to hook up (three gpio pins plus power, and since it's digital, i don't htink you have to worry as much about twisting wires to stabilize the signal). you don't need as many parts either, and you can ditch the hub too if you just want the one usb port from the pi. this is a popular one, i think: https://www.adafruit.com/product/3006

the one bad thing i've experienced with the i2s audio is that the volume wheel is really only useful at the top 1/4, and then it's just muted any lower than that.

i haven't tried this usb audio + amp, but it looks nice if you go the audio way: http://www.pocketadventures.com/product_cmusb10.asp

[infinitLoop]

here is the usb audio guide:

viewtopic.php?t=539

[rodocop]

Using a USB sound card with the PAM amp will be fine. I agree that PWM is often not great, so it's nice that you have USB. What I would do though, is wire the USB sound card to the volume wheel, then the headphone jack, and then add the PAM amp after the headphone jack to amplify the speaker only. I have found that most USB audio cards will power headphones totally fine, and amplifying it can make it too loud.

The link above will be good for your needs I assume, the only thing I would change is adding the amp after the headphones line mentioned above. with your amp, it should be the output from the headphone jack to the a+ (if you have L and R out, bridge them to a+) and ground to a- on the amp, then the output to the speaker.

The amp in the link above can handle stereo, while the one you have is Mono only, which is why I suggest bridging the L and R to a+

[FenderGreg]

Sorry, not about your audio but I'd be very interested to see the 'UK parts list' you found. I roughly know what I'm after but I generally find American sites. Thanks in advance

[rodocop]

I don't know about the UK list mentioned, but I have a excel sheet I put together a while back, showing parts to be used if you are doing a basic gameboy (no all-in-one board). Here it is, I just had a look this morning and updated a few things.

https://drive.google.com/open?id=1-7cCE ... ks4aeCqBs8

[FenderGreg]

I don't know about the UK list mentioned, but I have a excel sheet I put together a while back, showing parts to be used if you are doing a basic gameboy (no all-in-one board). Here it is, I just had a look this morning and updated a few things.

https://drive.google.com/open?id=1-7cCE ... ks4aeCqBs8

Great list, thank you!!

[BowmarDafty]

Using a USB sound card with the PAM amp will be fine. I agree that PWM is often not great, so it's nice that you have USB. What I would do though, is wire the USB sound card to the volume wheel, then the headphone jack, and then add the PAM amp after the headphone jack to amplify the speaker only. I have found that most USB audio cards will power headphones totally fine, and amplifying it can make it too loud.

The link above will be good for your needs I assume, the only thing I would change is adding the amp after the headphones line mentioned above. with your amp, it should be the output from the headphone jack to the a+ (if you have L and R out, bridge them to a+) and ground to a- on the amp, then the output to the speaker.

The amp in the link above can handle stereo, while the one you have is Mono only, which is why I suggest bridging the L and R to a+

Would you be able to explain or draw out a diagram explaining this? We are a little lost on the specifics.

You are suggesting that we use the PCM2704, to the volume wheel, to the amp, to the Headphone jack and then to the speaker?
How would you wire this?

Thanks for your reply!

[rodocop]

This is how I would wire it. See below:

SpoilerShow

Untitled.jpg (105.09 KiB) Viewed 5667 times

Try it out, see how it works, this will vary based on the headphone jack you are using, but you can see the pinouts of the commons ones used (viewtopic.php?t=701). Also, your USB sound card may vary. regardless, it will have an L out, R out, and ground somewhere.

[BowmarDafty]

This is how I would wire it. See below:

SpoilerShow

Untitled.jpg

Try it out, see how it works, this will vary based on the headphone jack you are using, but you can see the pinouts of the commons ones used (viewtopic.php?t=701). Also, your USB sound card may vary. regardless, it will have an L out, R out, and ground somewhere.

This is amazing! Thank you so much. Can't wait to get the group to test this.

Couple more questions - When you talk about the USB sound card, are you talking about the PCM2704 MINI USB Sound Card? Or are you talking about a general USB hub?

We have a board taken from a USB hub with 4 USB inputs, and we were wondering if that was what you meant?

Additionally, we're wondering if we're even going to need the USB hub if not... haha!

Thanks, again! Loving these forums.