Possible to use DB9 (RS232) to USB cable with MT32-Pi and DOS PC?

[sofakng]

I've seen videos (and documentation) that connect MT32-Pi to a DOS PC using a simple RS232-to-TTL adapter. (ie. DOS PC Serial Port -> RS232/TTL Adapter -> MT32-Pi)

However, would it be possible to use a cable like this?

USB to RS232 Adapter with PL2303 Chipset

I'm wondering if a combination of SoftMPU (serial port mode) + RS232/TTL Adapter + MT32-Pi would work?

[dwhinham]

I've just added support for this in a test branch.

It supports CDC class devices and the following commonly found chipsets: CH341, CP2102, FT231x, PL2303.
Other devices are not supported.

I don't have the ability to fully test this with a DOS PC right now, so I've just checked basic functionality with a CDC device.
If you want to test it, try this build (download sdcard and extract/install as normal): https://github.com/dwhinham/mt32-pi/actions/runs/946988682

There is a new usb_serial_baud_rate setting in the config file under [midi]. You must set this correctly to match the host device; you probably want to change it to 38400 to match SoftMPU's baud rate if that's what you're using.

If there's enough positive feedback I'll include this in the next release.

[sofakng]

Great! I’d love to give it a test.

Does the cable I linked to look correct?

Most of these cables have a male connector but we need a female like the one I listed to connect to the PC I think?

[dwhinham]

The cable you linked does seem correct for going directly into a PC, the Amazon reviews also seem to confirm that it's good for "null modem" purposes, which I am pretty sure is what we want (TX/RX are swapped).

If you have a cable with a male connector, you'll probably need to add a null-modem cable (which should have two female ends) between it and the PC to get TX/RX swapped, or use something like this: https://www.amazon.com/female-slimline-transfer-serial-adapter/dp/B075XGRLXW

[sofakng]

This appears to be working! I'm using this cable.

I've used the following commands:
SOFTMPU.EXE /MPU:330 /OUTPUT:COM1

...and then tested using DOSMID:
DOSMID.EXE /MPU=330 TEST.MID

...or it can directly output to the serial port:
DOSMID.EXE /COM1 TEST.MID

For some reason the notes sound wrong but I'm new to MT32Pi and could be using the incorrect ROMs or settings, etc.

Thanks so much for adding this ability!

[dwhinham]

Excellent, thanks for the feedback! Looks like we were right on the null modem/female connector idea.

If you're in MT-32 mode and the MIDI file you tested was a General MIDI song, it'll sound wrong, so you might want to try switching to SoundFont mode instead before playing the song.

You can set the default startup synth in the config (default_synth = soundfont), or on-the-fly with the DOS version of mt32-pi-control (mt32-pi.exe -g).

If your machine can run Windows, you could also try the Roland Serial MIDI driver for 95/98 or 2000/XP. This may let you use Windows MIDI-enabled games/programs with mt32-pi.

[sofakng]

Thanks for the information. I'm using the Secret of Monkey Island theme for testing since I know it pretty well and it's written for the MT-32. I also have a real MT-32 connected to my other PC (using a UM-ONE adapter) so I can compare it.

I'll perform some additional testing but I'm guessing it's something I'm doing wrong because the instruments seemed wrong and not the pitch/speed or anything else but I'm not positive.

[sofakng]

Awesome, thanks so much. I think I might have a similar cable at home using the (better) FTDI chipset. I’ll test and report back. Thanks so much!

…

On Jun 17, 2021, at 12:30 PM, Dale Whinham ***@***.***> wrote:  The cable you linked does seem correct for going directly into a PC, the Amazon reviews also seem to confirm that it's good for "null modem" purposes, which I am pretty sure is what we want (TX/RX are swapped). If you have a cable with a male connector, you'll probably need to add a null-modem cable (which should have two female ends) between it and the PC to get TX/RX swapped, or use something like this, which does the same job but in a smaller package: https://www.amazon.com/female-slimline-transfer-serial-adapter/dp/B075XHWVSJ — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or unsubscribe.