Connect MT32-pi hat without I/O board?

[rhester72]

If I'm building the MT32-pi hat (see https://github.com/dwhinham/mt32-pi/wik ... connection) for direct use with MiSTer, but *don't* have an I/O board, is it possible to tap the required connections for the user port directly on the DE10-Nano? If so, where is each connection located (that are brought out to the user port)?

[aberu]

https://github.com/MiSTer-devel/Hardwar ... rd_6.1.pdf

This is the schematic for the analog I/O board.

https://github.com/MiSTer-devel/Hardwar ... ig_1.2.pdf

Here's the schematic for the digital i/o board.

I know that the headers from the i/o board for the usr port connect somewhere in here:

2021-01-28_14-29-00.png (815.02 KiB) Viewed 10003 times

Here's the relevant section of the analog i/o board's schematic, for reference.

2021-01-28_14-31-27.png (22.7 KiB) Viewed 10001 times

[rhester72]

VERY helpful, thank you so much!

[scyto]

this is cool

I have a SC55mkII on my desk i use for old dos games, besides a smaller formfactor would pi-mt32 give me other advantages with mister?

[cognitivegears]

Yes! I just got this working last night in fact. This works fantastic. I didn't have an I/O board (no real need currently besides,) nor the mt-32pi hat. I was able to hook this up with just a bare PI and bare de-10 nano. A couple of notes:

* The user port connection page has been updated with Pinout information, perfect for what we want to do.

* I used jumper wires, like these from Amazon. I just ordered a dupont connector kit to make something a little more permanent.

* I didn't use the 5V line or the unused RX (midi in) line, so in my case there were 7 pins to connect. You can do the 5V line if you want to, I chose not to for 2 reasons. 1) the VCC line on the DE10 is the only pin that is not in line, so I'll have to reach across the board to get it, and 2) I care more about my DE10 Nano then my Pi and powering it from the DE10 just seemed slightly dangerous and not worth it when I can just plug in the Pi separately. Your choice though.

* I used the MiSTer user guide to get the locations to attach the pins (page 30).

* Here is a good diagram of the Pi pinout. From here I just made a quick mapping text document of Pi Pin / Color / DE10 Pin, so that I could get them all in the right place. I started with the DE10 side because they are all in a line so I could get the colors from the ribbon, then matched from there to the Pi side.

* This thing is fun y'all, you should try it. And for less than $10 for the cable, plus a Raspbery Pi (you could go with a $25 Rpi 3 if you don't already have one), a 8GB, a $5 micro SD card if you don't have any laying around it is pretty affordable. Maybe $40 all told to get MT-32 and general Midi on your DE10-Nano. Compared to $50 for the MiSTer IO board, plus probably $40/$50 to build the MT32-Pi RPi HAT, plus the pi still I was looking at $130 ish to get the setup using the User port, and that's probably conservative. Plus a lot more time to build it. I miss out on the physical LCD screen, but I can live with that.

Let me know if there is anything I can help with or if you have any questions!

[cognitivegears]

this is cool

I have a SC55mkII on my desk i use for old dos games, besides a smaller formfactor would pi-mt32 give me other advantages with mister?

Several potentially: You can install your own soundfonts for general midi, and you can install multiple ROMs for the MT32 side. Also it routes the sound back to the DE10Nano and is mixed with other sound (if it supports SB/MT32 etc)

That said, I'm kinda jealous of your physical SC55 and except for the above points would love to also have a physical device too.

[cognitivegears]

Also a few pictures of my (currently ugly but functional) setup. Linked instead of images so people who don't want them can scroll on by.

Setup:

6idHRN7.jpg (1.49 MiB) Viewed 5560 times

(the two pins left dangling are for the 5V and RX that I didn't end up using)

Raspberry PI side:

5BUZT6U.jpg (920.13 KiB) Viewed 5560 times

MiSTer side:

NKFS3he.jpg (975.76 KiB) Viewed 5559 times

(ignore the pin pulling out here, it was just moved around for the picture)

[rhester72]

@cognitivegears Did mine all with single straight jumper wires, so it's a bit dumpy...wouldn't mind something a little cleaner. Happen to have a link to the cable you bought?

[cognitivegears]

@cognitivegears Did mine all with single straight jumper wires, so it's a bit dumpy...wouldn't mind something a little cleaner. Happen to have a link to the cable you bought?

Here is the ones I am using currently: https://www.amazon.com/gp/product/B07H9T7H34

I just left this as a ribbon instead of splitting into separate jumpers.

That said, tomorrow I'm going to be getting a dupont kit in so that I can make my own connectors, which should look a lot better. I didn't link it on the last post because I haven't tried it yet, but in theory this should be even cleaner and I can update this once I get that done. In case you want to try that one this is the one I ordered: https://www.amazon.com/dp/B07ZK5F8HP

[rhester72]

Thanks! I'm now contemplating doing something slightly different and trying to integrate a solution into my ClumsyMIDI hat so I can use it for both...but this was very useful!

[cognitivegears]

Finally got around to putting together a Dupont cable. Turned out pretty good, although the RPi side doesn't have all the pins together, so I did a 3 pin connector, a 2 pin, and two 1 pin connectors. In practice this is still a lot nicer (especially on the MiSTer side,) though the previous solution with jumper cables worked too - if that is what you have I wouldn't let it stop you from trying this out. Note: I'm using 7 pins here because I don't really care about 5v (personally I'd rather power the RPi separately.) See below for a pic of the finished cable:

3O0I6Wa.jpeg (1.32 MiB) Viewed 5555 times

[cognitivegears]

Thanks! I'm now contemplating doing something slightly different and trying to integrate a solution into my ClumsyMIDI hat so I can use it for both...but this was very useful!

ClumsyMIDI looks really nice too. I guess you'll use a USB to Midi converter? That will be pretty slick I bet, please post when you get it all done!

[chanunnaki]

Just cross-linking this here in case anyone missed it.

viewtopic.php?f=13&t=2168

[werpu]

Thanks for all the info, I did a direct cable connection from my io board to the mt32 pi (I cut off a usb3 cable and crimped the wires into dupont connectors)
Works like a charm and cost me a few bucks for the cables, that was all, given that I always have an extra spare pie somewhere in a drawer. The hardest part was to splice the usb3 specific data wires from their signal insulation (did not have a chirurgical knife which would have helped)

You really do not need the hat, if you can live without the display (which I can, because everything goes into a case anyway)