My First GBZ Build (Noob Questions Galore)

[jhk1976]

Hello everyone,

I discovered the GBZ a couple of weeks ago as I was pondering a new project to take on. I like what I've seen on here, and have spent the last couple of weeks gathering parts so that I can get started. I'm using the long weekend as a chance to jump in!

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As I am new at this, I have questions galore. I've been drawing diagrams of how I plan to wire everything up. I have a lot of it figured out, but there are a few other things I wonder about. My goal is to use as few boards as possible, but as I could not get my hands on an AIO board, there will be a few more in there. I actually don't mind this, as I wanted this project to be a learning tool for me as well.

So on to the questions, and thank you all in advance for the wealth of knowledge you've already shared here on Sudomod.

1. From what I can tell, the only two devices that I will need 5v for are the Pi Zero and the screen. I have a Gearbest screen on order, but it isn't here yet. Is there a way to successfully power both without needing a power strip board?

2. I need a ground connection for the micro USB breakout board, but the two ground pinouts on the Powerboost are used by the grounds for the switch and the Pi Zero. Is there somewhere else on the PB I can connect to for ground? Can I use the ground connector for the standard USB port I didn't end up adding to it? If not, would connecting it to a ground on a different board, such as the pi or the common ground board be an option? I figured ground is ground, but I wanted to be sure.

3. For those who use the DC jack to charge instead, how exactly are you wiring that up to the Powerboost? Are you using the stock GB connector, or are you obtaining an after market connector obtained elsewhere? If so, can you suggest where to get one?

I'll have more questions as I go, and I KNOW I will have questions when I get to the audio. Thanks again in advance, and please be patient as I learn. Everyone's new at something at some point in their lives.

Parts List:
Used GB DMG-01
Gearbest 3.5" Screen (on order)
Pi Zero W
Kitch-Bent Common Ground DMG Button PCB (A/B/X/Y version)
Powerboost 1000C
Adafruit MAX98357A I2S Amp
Adafruit UDA1334 I2S DAC (if I can make it fit -- it has a headphone jack and Ferrite already built-in
Sabrent USB Audio Board (in case I decide not to go the I2S route)
Erik Gee's Shoulder Button Bracket and Board
Wermy's Bracket Kit
The usual other assorted parts: USB jacks, potentiometer wheels, headphone jacks, switches, spare buttons, etc.

[tinkerBOY]

I made a diagram for my simple v1.1 board but can also be used for other boards.

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1. Power strip makes it easy to distribute power to each devices.
2. You can connect to any GND on the Pi, battery, etc.

[jhk1976]

Thanks for the reference!

I do have a power strip on order. I wanted my build to be as clean as possible, the fewer boards the better. I'm not averse to using one if I have to though. My used GB showed up a few days ago, and having not held one since my own childhood, they are much smaller than I remember. I can see where real estate is a concern with these builds.

I ended up ordering a lot of extra parts I may not even need. Everything was pretty cheap, and since I wasn't totally sure which routes I was going to take for certain things (USB audio versus I2S for example), I figured it couldn't hurt to have everything on hand in case one path didn't work out for me. Leftover parts can be used for perhaps a second build -- if I can make the first one work, natch.

[CrogDog]

This is the 3.5mm DC jack I used for charging on my recent build
https://www.amazon.com/DCFun-1-35mm-Fem ... mm+dc+jack
Speaking of leftover parts I still have 9 left I'd be happy to send you a few if you're still in need or haven't purchased any yet.
On my build I wired the positive to the USB pin on the powerboost and ground to the GND pin

[jhk1976]

Thanks for the tip. I'm on the fence about whether to use a barrel jack or the micro USB breakout. I was thinking I'd use that spot for a power LED and place the breakout elsewhere. I'll let you know Knowing how it wires up helps a lot though.

[jhk1976]

Progress and setbacks...

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I got my case modded up to my liking and have installed Wermy's button wells, my Kitsch-Bent controller board and Erik Gee's L/R button brackets. They look great! I've also soldered up the wiring, which I will trim to size once I get everything where I like it. I'm sort of staging everything in the meantime.

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My Gearbest screen was working last weekend when I tested it, but when I went to test it again this weekend, it wasn't. I've been extra careful with the cable, so I don't get what happened. I've ordered a replacement, but it's still frustrating. This also happened AFTER I had it glued into the case, so I had the joy of having to peel away all the hot glue that held it in. I would have much preferred a TFT screen with pinouts. They seem far less delicate.

I also had a horrific time wiring up the headphone jack. I'm good at soldering to breakout boards, but far less so with standalone metal contacts. I either get goopy, sloppy solder joints or melt away half the plastic housing in the process. I'm opting for breakout boards wherever I can as a result. Has anyone had any luck with a headphone breakout board like the one pictured?

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To be continued...

[CrogDog]

Bummer about the screen That hole would be a great spot for an led indicator. I went with the 3.5mm barrel jack since I already had a cord for it and for the factory kind of feel, but honestly a micro usb would have been more convenient for charging. There's a decent amount of space along the bottom where you could put a charging port. Can also use a lightning connector breakout board if you're an Apple user

[jhk1976]

Yeah, I was back and forth about a DC barrel jack, but I do think the micro USB will be the way to go for me. I plan to mount mine at the bottom of the case too.

My headphone jacks with breakout boards should be here today, and my USB breakout board for the data connection should be here by week’s end. The replacement screen is due in Wednesday. Hopefully I’ll be most of the way there by next weekend. Assuming no difficulties with any of these, the next hoop to jump though will be wiring up the potentiometer.

[jhk1976]

My headphone jack breakout boards arrived today, and I'm pleased to say that I think these will work out great!

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The one problem I did have to solve was the size of the jacks they came with. As you can see from the photo, they're bigger than the jacks I had ordered off of Amazon, with much longer pins. I did a test fit, and the case wouldn't close with this configuration. The solution? I used the shorter jacks I already had with the board instead of the jacks it came with.

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The end result is a headphone jack attached to a breakout board, which was an absolute JOY to solder.

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The one drawback is that the board is a bit large, and winds up sitting on top of the end of the controller board where the plastic peg pokes through that holds the start and select button membrane in place. I ended up using a hobby knife to make that peg slightly shorter to accommodate the board. I did a test fit in the case and it's a very nice fit. The fit wouldn't be a concern if I had Dremeled out the battery compartment, but as I left mine in to accommodate the Li-on battery, there's not as much clearance when you close the case. In order to make this work with the battery compartment intact, you have to shave off the raised supports that held the old GB headphone jack in place. I did this back when I was modding the case just so I'd have some extra room to play with. It JUST fits, with the board sitting pretty flush against the back of the battery compartment when the case is closed.

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That lack of clearance means I'll have to solder the wires to the underside of the fitted board, but I can live with that. Just having a breakout board to attach it all to makes it all the nicer.

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[jhk1976]

I have a working screen. Huzzah!

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It looks like a little of the text is getting cut off though, especially in the configuration menu. Overscan is turned off and the screen has been forced to 320x240 in the /boot/config.txt file. Anybody know how to get that to fit more nicely?

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Next step is to mount up the screen, and then start wiring up everything to the Pi.