Cheap DIY Mini ITX Build w/ MT32-Pi

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notaburger
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Cheap DIY Mini ITX Build w/ MT32-Pi

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Hello everyone. I know what you're thinking: ANOTHER mini ITX build?!? Why? Well, I had a very specific set of wants out of such a system and I didn't see that anyone had done it yet.

I wanted:
  • To keep it as cheap/low fuss as possible. Although it would be very easy to just buy a full kit, I didn't see why it was necessary.
  • I couldn't find an example online of someone building straight off the bare board into a mini itx case without using existing Mister boards and/or fancy jacks and extensions.
  • It needed to be able to fit a Pi for MT32 Pi functionality.
First off, a few points:
  • Yes, I 3d printed some of these parts but that is entirely optional. Don't let anyone shame you if you want to use sticky foam squares, hot glue, whatever. You do what you can to make it work and I'm sure you'll be happy.
  • I purchased the listed mini ITX case off of Amazon as I felt like it was a clean design, cheap, and gave me a few features I could work with. This one only has one button and one USB port but what I’ve included here should apply to other similar cases as well.
  • There are a few items that I have here that are optional. I tried to make it clear when applicable.
  • As always, I’m providing my instructions here for reference only. You’re on the hook should you mess anything up trying to follow along. Remember to double check any wiring prior to turning on the system for the first time.
Now, let's gooooo.

3d Printed Base
You can get my files here: https://www.thingiverse.com/thing:4996096
I mounted the DE10 to the print using the hardware that was provided with the case. For the Pi I had to supply my own. Here are a couple pics of that process.

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As previously stated, you don’t have to print this. If I didn't have access to a 3d printer, I'd have probably put the plastic cover of the DE10 on the bottom, put the Pi in a <$5 case, and then used command velcro strips to hold them in place.

Case mods - USB
I had a scrap piece of PCB Prototype Board and some header pins, so I opted to build a small connector for my USB. I know how crude it looks, but I didn’t want to bother wasting time cutting a new board and making it look pretty. I wrapped it in electrical tape to minimize the risk of any shorts should it move around.

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If you want, you can splice a micro USB cable with the case wires and then plug it in directly to the DE10 and not worry about using a hub. Personally, I could have gotten by with that, but I figured that more would appreciate a few extra ports, so I designed my case configuration to accommodate that cheap Micro USB OTG "squid" style hub that a lot of people use. Plus, using the hub allows the usb ports to be powered externally, reducing the load on the Mister. If I didn't do that, I'd have had to power the Pi separately as many wireless dongles draw a little too much current with the stock power supply and MT32. If you do that and you are modding an existing micro USB cable, don't forget to short the Sense and Ground wires. If you are modding an existing USB 2 cable to go into the OTG hub, then this is not necessary (there will only be 4 wires).

No matter what you do, you should verify that everything is wired up correctly before plugging into your DE10. You can do this by checking resistance between pins using a multimeter.

For your reference, here are the pinouts for various USB Connectors:

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Source: USB hardware - Wikipedia https://en.wikipedia.org/wiki/USB_hardware

Case mods - Power LED
Since this is a cheap case from overseas, I didn't take anything for granted. I disassembled the control board and verified the installed resistor. Mine had a 100 ohm resistor and the blue LED had a voltage drop of about 2.3v, which, given a 3.3v supply from the DE10, should cover us quite nicely for the expected current rating of the LED. https://ledcalculator.net/#p=3.3&v=2.4&c=10&n=1&o=w

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I wired the LED to the DE10 as shown below:

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Case mods - Menu Button
Unfortunately, most mini ITX cases will only have one provided button. For me, the most critical of the available functions is the MENU Button, so that's what I wired it to. Using the Analog IO Board schematics, I determined that this function is triggered by shorting pin 13 to pin 12 (ground) as shown below.

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If you want, you can wire to pin 15 instead for the USER Button or pin 17 for the RESET Button.

If you so choose, you can probably find a drop-in replacement switch that you could wire up to control the main power to the Mister, but I didn’t have a need for this. I use a smart plug and turn it on that way. In the past I’ve also just used a switch on the surge protector. Ultimately I decided that it wasn’t worth the hassle or extra cost and that a menu button would serve me better.

Once I had my wires installed, I wrapped them in electrical tape to help hold them in place.

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IO Plate
You can get my files here: https://www.thingiverse.com/thing:4996096

Alright, we’re in the home stretch. Yes, this is another 3d printed part, but this too is an optional component. Don’t feel bad about having some wires dangling out the back of your case if you don’t have a 3d printer. For those that do have a 3d printer, I have included step files so that you can tweak them based on your personal preferences. This would allow you to drop a port, add something like a window for the micro usb cards, or move stuff around. This plate is designed as a press fit that is further held in place by the lid’s mounting screws.

The Ethernet Keystone Jack is completely optional. You can use a wireless USB dongle instead or simply run a longer cable thru the open hole.

Wrap-up
Install the DE10 and Pi (if applicable) to the case. If you’re using the 3d printed base, then you can utilize hardware provided with the case.

Do whatever level of cable management that makes you happy.

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One last time, make sure that all of your wiring is correct and has been secured before you close it up.

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Time to play some games!

Parts List:

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(If amazon links are not allowed, please let me know and I'll remove them. Note: These are NOT affiliate links.)

https://www.amazon.com/gp/product/B07HCG9RVV/
https://www.amazon.com/gp/product/B07GD2BWPY/
https://www.amazon.com/dp/B003L1AET2/
https://www.amazon.com/gp/product/B01FHC1964/
https://www.amazon.com/gp/product/B01D0Z8PLW/
https://www.amazon.com/gp/product/B00LTHBCNM/

Minimum Cost - $63.89
Full Cost (not including DE10) - $102.43
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