MIDI to USB (again)

[kaiki]

I want to build a 'SIMPLE' Midi out to USB cable? so just a single midi out from a keyboard into the computer.

i've seen the mbhp_usb module, but it seems to be overkill for what I need.

So my question is: is it possible to make such a circuit simply using the FT232{R,B}?

i'm guessing it should look like this :

MIDI out -> optoisolator ->(isolated 5V) -> FT232B to usb (computer). I know I can get the data into the FT232 but from there on how would the computer recognise it as a MIDI device?

[lylehaze]

Yes, No, and Maybe! ::)

The FT-232R is capable of MIDI baud rates, which are a bit different than the usual serial stuff.

But the "usual" serial port drivers that they emulate have only a lookup table for the normal

speeds, so you would have to persuade the driver to let you select your own baud rate. I have

lots of information on the chips, but I don't do windows, so I don't know what it's drivers are

capable of. Maybe changing a lookup table entry somewhere.

So you MAY be able to get 31250 baud, but how do you make it look like a MIDI device? That could

be the biggest problem. It's possible to change the device codes a bit, but not to re-write the

entire device, as far as I know. So let's assume the answer is NO.

You CAN make it look like a serial port, since that is it's natural purpose. So the best shot you might

have might be to try and use the Yamaha "ToHost" serial port -> MIDI driver. It'll let you use a

"normal" serial port for MIDI, and it just might work with an FTDI USB chip! I wrote a similar driver for

the classic Amigas a few years back. Again, I'm not too familiar with the windows versions, but it

MIGHT work.. Maybe.. Just maybe.

Have fun, and let us know what you learn!

LyleHaze

[kaiki]

the FT232R i think will easily work at 31250 baud, it has very versatile settings to change baud rates, i did a quick calculation based on their datasheet and it seems to be okay.

okay so we have the FT232R converting the TTL levels to USB okay, now if I understand correctly the computer has to recognize it as a MIDI port??  (actually I don't care if its windows or linux)

can't the software (things like jazz++ or whatever else works with midi) recognise just streams of data as midi, or does there need to be other data as well (special headers/footers)

won't it work if the USB device gets a virtual COM port on the computer and all the application sees is a stream of serial data (that happens to be midi?)

[lylehaze]

If you want it to appear as a USB MIDI device, it will need

to respond as described in the "Universal Serial Bus Device Class Definition for MIDI Devices", also known as midi10.pdf.

Otherwise it'll look like a serial port.

[lylehaze]

Try a search for "Yamaha CBX Driver"

It'll bridge serial to MIDI.. Just might work!

LyleHaze

[dj3nk]

The driver works fine. But how to connect a device to com ? i can't find any wiring information.

perhaps you or somebody else here knows? I found a picture of the original yamaha cable and it looks nearly like a 1:1 connection.

[mess]

You could use a midibox ltc module for the wiring..

it takes care of all level convertions

just replace the rx and tx connections the the pic

with the rx and tx from the FT232R...

[lylehaze]

So a LTC board wired to a SMT chip with an odd driver..

At some point it just makes sense to buy a simple

MIDI cable like the UNO..

Even if it is "less fun"

LyleHaze

[AndrewMartens]

At some point it just makes sense to buy a simple

MIDI cable like the UNO..

Even if it is "less fun"

That's what I was thinking.  For a 1-in, 1-out interface, you should be able to buy something relatively cheap.  Even looking at multi-port MIDI interfaces, I think if the 4x4 MIDIbox USB idea was up and running, then it *might* be price-competetive with some commercial devices.  Still, I got a brand-new MOTU MicroLite (5x5) interface for only $153 CDN (regular price).

[kris]

both midi box projects ive built ive used midisport 2x2 midi usb available very cheap beats the hell out of reinventing the wheel