MiSTer FPGA Forum

Hi Ive just received a MT32-pi kit from UltimateMister and am using a MisterMultisystem.
Where do I connect the short USB3 cable to the Multisystem/DE10 to use it?

Thanks.

https://RMCRetro.com/mmsguidev2

Snac port.

IRONBERG wrote: ↑Tue Mar 14, 2023 7:23 am

https://RMCRetro.com/mmsguidev2

Snac port.

Hi are you sure it is to be connected to the SNAC? and not the DE-10 itself?
I read the manual yesterday, and didn't see any mention of it being useable for anything but SNAC adaptors, and obviously I don't want to risk any damage to circuitry.

Thanks

Fpg-lee wrote: ↑Tue Mar 14, 2023 7:32 am

IRONBERG wrote: ↑Tue Mar 14, 2023 7:23 am

https://RMCRetro.com/mmsguidev2

Snac port.

Hi are you sure it is to be connected to the SNAC? and not the DE-10 itself?
I read the manual yesterday, and didn't see any mention of it being useable for anything but SNAC adaptors, and obviously I don't want to risk any damage to circuitry.

Thanks

Hello, the Multisystem can be set to be a USER port (3.3v signals) or the SNAC port (usually 5v for game controls etc).
Multisystem does not require the use of the SNAC level shifter board as we integrated all that into the Multisystem, just selected by J17.

To use a MT32Pi on the Multisystem all you need to do is have J17 jumper set to be 3.3V (Pins 2+3 linked) and set the switch SW7 to be IO6. Then just connect the MT32Pi into the User/SNAC port of the Multisystem.

We have also made a dedicated cartridge for the MT32Pi (called the Pi-MMS) that just plugs straight into the Multisystem universal expansion connector. No setting changes are required and the status of the switch SW7 or the jumper J17 do not matter when the Pi-MMS cartridge is used.

Hi thankyou for the very in-depth reply and help.

I have set the J17 jumper to 3.3v and SW7 to IO6 and the MT32PI is connected to the SNAC/USER port via the short USB3 cable coming from the Pi
*not the Pi hat USB which is empty, but the screen on the hat is off, with seemingly no power to either Pi or hat.

I have not touched the MT32PI's supplied SD card since it was pre-installed, all I have done is use soundfont installer.sh and midilinkupdater.sh to download midi fonts and whatever other files that comes with said scripts.
Is there anything wrong with this set-up?

Lastly, if I do purchase the PiMMS cartridge, can I use my supplied Pi3+ with said cartridge? albeit protruding up and above the Multisystem's dust cover?

Thanks again.

multisystem wrote: ↑Tue Mar 14, 2023 8:51 am

Hello, the Multisystem can be set to be a USER port (3.3v signals) or the SNAC port (usually 5v for game controls etc).
Multisystem does not require the use of the SNAC level shifter board as we integrated all that into the Multisystem, just selected by J17.

To use a MT32Pi on the Multisystem all you need to do is have J17 jumper set to be 3.3V (Pins 2+3 linked) and set the switch SW7 to be IO6. Then just connect the MT32Pi into the User/SNAC port of the Multisystem.

Can the SNAC port on the multisystem be used while the Pi-MMS is installed? My understanding is no, one or the other.

And as some feedback, with the rarity and cost of the pi boards, it really is a shame the Pi-MMS internal pi header wasnt utilized as such. The design could be improved to allow the user to easily remove/replace the pi like any other removable hat header, instead of permanently soldering the pi and Pi-MMS board. Kind of a big miss.

Ok so I have managed to get the MT32-Pi working by turning the Pi power switch off, feeding power to the Pi via one of the spare front USB's on the mister (Micro USB to USB A) and altering the Pi SD config file to ignore the "low voltage chk pwr" message the Pi hat displayed previously when it was hooked up to the adjacent USB 2.0 port.

This still doesn't explain why the Multi isn't supplying enough power to the MT32-Pi when I followed the above manufacturers settings to use via the USER/SNAC port.

Lastly I concur with the above poster, that we need clarification on whether the SNAC port can still be used at the same time as the Pi-MMS otherwise, this is an unfortunate oversight in the Multi-system's design.

p.s my Multi has an uprated power supply, not the one that comes with the DE-10 stock.

Fpg-lee wrote: ↑Wed Mar 15, 2023 7:38 pm

Ok so I have managed to get the MT32-Pi working by turning the Pi power switch off, feeding power to the Pi via one of the spare front USB's on the mister (Micro USB to USB A) and altering the Pi SD config file to ignore the "low voltage chk pwr" message the Pi hat displayed previously when it was hooked up to the adjacent USB 2.0 port.

This still doesn't explain why the Multi isn't supplying enough power to the MT32-Pi when I followed the above manufacturers settings to use via the USER/SNAC port.

Lastly I concur with the above poster, that we need clarification on whether the SNAC port can still be used at the same time as the Pi-MMS otherwise, this is an unfortunate oversight in the Multi-system's design.

p.s my Multi has an uprated power supply, not the one that comes with the DE-10 stock.

The MiSTer USER/SNAC outputs can also only be used for either the SNAC/USER OR the MT32-Pi - the Multisystem is exactly no different in this respect. It's a physical limit of the MiSTer design architecture of the DE10-nano - nothing to do with the Multisystem. We could have implemented different I/O to do the Pi-MMS, but then it would not have been compatible with the cores who use the SNAC/USER port I/O to do all communication with the MT32-Pi / Pi-MMS.

The stock 'Stack MiSTer design' is not ideal to deliver power to devices like the Raspberry Pi via the USER/SNAC port, you will have problems using powerful Raspberry Pi's and with longer USB 3.0 cables etc.

Pulling power from the front USB ports is also not a good idea for high powered Raspberry Pi devices, we do allow high current output from these ports for SSD's but if you start pulling more than around 1.8A total it's likely to cause you problems on the Multisystem and it'll probably be a lower limit than that via the MiSTer Stack design.

The Multisystem USER/SNAC port is tracked so it can actually deliver higher power output on the 5V, but again it's not an ideal solution. Higher powered Raspberry Pi boards like the 3 and 4 may need an external power supply or you can risk causing damage even on the generic 'Stack MiSTer design'.

This is why we made our own dedicated Pi-MMS cartridge that connects directly to the Multisystem expansion.
It's also why we used the Raspberry Pi Zero 2/2W in the cartridge design, for power & efficiency, but we can deliver several Amps of 5V via the expansion power if ever required.

all of that makes perfect sense but why didnt you make the pi-MMS a normal/removable pi hat? soldering it down -onto a header- is... strange

They most likely did it that way so it can fit in a slim case. You can always modify it by swapping out the pin header for a female header or using a female header on the PI and using it as hat but then you'll need to either not use the case or design and 3D print a new case to fit the protruding PI.
You may be able to get a hold of low profile headers but they will still take up more space then directly soldering a PI to the pin headers.

Flandango wrote: ↑Sat Mar 18, 2023 1:37 pm

They most likely did it that way so it can fit in a slim case. You can always modify it by swapping out the pin header for a female header or using a female header on the PI and using it as hat but then you'll need to either not use the case or design and 3D print a new case to fit the protruding PI.
You may be able to get a hold of low profile headers but they will still take up more space then directly soldering a PI to the pin headers.

yep, i started prototyping different ways to attach it and the studying how i would need to redesign the case to accomodate... just seems like this effort should have been made on the front end of the process when fitment and pcb design were considered. oh well i guess im just lucky to even have a pi2w, i guess its going to be permanent!

Missus wrote: ↑Sat Mar 18, 2023 7:09 pm

Flandango wrote: ↑Sat Mar 18, 2023 1:37 pm

They most likely did it that way so it can fit in a slim case. You can always modify it by swapping out the pin header for a female header or using a female header on the PI and using it as hat but then you'll need to either not use the case or design and 3D print a new case to fit the protruding PI.
You may be able to get a hold of low profile headers but they will still take up more space then directly soldering a PI to the pin headers.

yep, i started prototyping different ways to attach it and the studying how i would need to redesign the case to accomodate... just seems like this effort should have been made on the front end of the process when fitment and pcb design were considered. oh well i guess im just lucky to even have a pi2w, i guess its going to be permanent!

The Raspberry Pi Zero 2 does not come with a pin header as standard, you can fit it front or back, so whatever we did would have potentially been wrong for 50% of people who already had decided to solder their header onto the Pi Zero. It also takes up a lot more room in the cartridge having a removable header. Once it's fitted it is a dedicated Pi expansion cartridge, the MT32-Pi is not the only thing you can do with it, so it seems reasonable for it to be fitted permanently, but feel free to use a removable connector if you like.

We also originally planned to supply the Pi already fitted, but the global shortage stopped us from doing that. We made the decision to carry on but allow people to fit their own so at least they were available for anyone who can get hold of a Pi Zero / Zero2 / 2W

I'd just like to send a big thanks out to Dale (d0pefish) for his tireless development of the mt32pi. He released a new update to the s/ware v0.13.1 2days ago, it's available on his github page. https://github.com/dwhinham/mt32-pi