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to-host serial-to-MIDI port

to-host serial-to-MIDI port

2009-12-16 by Alan

Hello,
  I just won a Kawai Gmega tone module on ebay and noticed that it has a serial port-to-MIDI connector like many mid-1990s tone modules do.  This is a miniDIN8 connector. 
  This is an interesting feature as it allows the PC to send/receive data from the synth and converts that data into MIDI signals.  It converts the 38400 baud RS232 serial into 31250 baud serial and back again.  With this port, I can use Visual BASIC 6 serial I/O COM port routines to send/get sysex without using the cryptic and incomprehensible Windows API functions to access the MIDI port.
   The Yamaha manuals for the synths of that era have this connector documented and I have been able to get it working by making a custom cable and installing the to-host driver from Yamaha.  
   Does anyone know if these ports are 'standard' between the other synth manufacturers?  Will a custom cable made for a Yamaha work on the miniDIN8 serial port of the Kawai?  
   I sent an detailed e-mail to Kawai tech support and got back an order form to buy the service manual at a cost that is greater than I paid for the tone module itself on eBay.  And I would have no way of knowing if the information that I'm looking for would actually be in the service manual.  So much for tech support, but then, it is a rather old piece of equipment.  But if Yamaha can make the service manuals and schematics available in PDF, why can't Kawai?  Actually, the PDF of the schematics was probably done by someone who scanned the schematics from service manual that they had to buy to get the information.  But why can't they just give me a simple answer to a simple tech question?
   Anyway, these serial ports were popular from the mid-1990s until the USB era and they are found on Yamaha, Roland, Korg, and Kawai tone modules.  Are they all compatible?  Does anyone have any experience with them?  I may end up poking and probing around with it (find the ground pin, find data out by doing a sysex dump from the front panel, etc...), but maybe someone here has already done all that.

Re: to-host serial-to-MIDI port

2009-12-16 by narfman96

Alan, This is a Mac serial port and all are the same. Alesis, Korg, Roland, Yamaha, etc. Some will run at 115800 baud....   Fran

--- In vintagesynthrepair@yahoogroups.com, "Alan" <alan_probandt@...> wrote:
Show quoted textHide quoted text
>
> Hello,
>   I just won a Kawai Gmega tone module on ebay and noticed that it has a serial port-to-MIDI connector like many mid-1990s tone modules do.  This is a miniDIN8 connector. 
>   This is an interesting feature as it allows the PC to send/receive data from the synth and converts that data into MIDI signals.  It converts the 38400 baud RS232 serial into 31250 baud serial and back again.  With this port, I can use Visual BASIC 6 serial I/O COM port routines to send/get sysex without using the cryptic and incomprehensible Windows API functions to access the MIDI port.
>    The Yamaha manuals for the synths of that era have this connector documented and I have been able to get it working by making a custom cable and installing the to-host driver from Yamaha.  
>    Does anyone know if these ports are 'standard' between the other synth manufacturers?  Will a custom cable made for a Yamaha work on the miniDIN8 serial port of the Kawai?  
>    I sent an detailed e-mail to Kawai tech support and got back an order form to buy the service manual at a cost that is greater than I paid for the tone module itself on eBay.  And I would have no way of knowing if the information that I'm looking for would actually be in the service manual.  So much for tech support, but then, it is a rather old piece of equipment.  But if Yamaha can make the service manuals and schematics available in PDF, why can't Kawai?  Actually, the PDF of the schematics was probably done by someone who scanned the schematics from service manual that they had to buy to get the information.  But why can't they just give me a simple answer to a simple tech question?
>    Anyway, these serial ports were popular from the mid-1990s until the USB era and they are found on Yamaha, Roland, Korg, and Kawai tone modules.  Are they all compatible?  Does anyone have any experience with them?  I may end up poking and probing around with it (find the ground pin, find data out by doing a sysex dump from the front panel, etc...), but maybe someone here has already done all that.
>

Re: [vintagesynthrepair] Re: to-host serial-to-MIDI port

2009-12-16 by GB

> Alan, This is a Mac serial port and all are the same. Alesis, Korg, Roland, Yamaha, etc. Some will run at 115800 baud.... Fran

If that's true then you can find some info on the web for the mac interfaces. I've seen schematics for the Midiman Mini MacMan (r whatever it's called. Iwas actually looking for an RS232 to MIDI adapter and that's what I came up with.
I'm still looking for a cheap adapter that converts 32150baud RS232 level signals into the equivalent MIDI IN OUT.
GB
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Re: [vintagesynthrepair] Re: to-host serial-to-MIDI port

2009-12-17 by Alan Probandt

Thanks for the reply. I would be curious to know why a MIDI signal would need to be converted to RS232 levels at 31250 baud. MIDI is a 'current loop' in that the same electrons come from the MIDI transmitter through the MIDI receiver and then back to the original source. RS232 uses +9 volts for active signal and -9 (to -15) volts for inactive signal.
I have used an AVR microcontroller type Mega164 to make a MIDI-to-RS232 converter. This was easy to do because the Mega164 has two serial port UARTs in it that both have input and output signals. Set one serial port to 38400 baud and the other to 31250 baud. Then whatever byte comes into one port goes out the other. A PC-to-MIDI convertor for less than $10. But my difficulties aren't with hardware. It's being unable to use the PC MIDI port at all with straightforward code. If I could get the sysex dumps into the PC then I could put the parameters on the screen and make a general purpose editor program for all the tone modules out there.
With the old MPU401, it was simple. A bit in a byte located at a specific I/O address would go high to indicate that a new data byte had arrived. Another bit would go high indicating that the 401 was ready to receive a byte for transmission. Send the dump request string and then collect bytes from the 401 into a buffer until it received 0xF7. But it can't be done with modern Windows because there are several undocumented software layers between the MIDI port and the application program code. So MIDI dies a slow death and the tone modules sell on eBay for 1/20th of what they did 15 years ago.
Anyway, I will research Apple Mac MIDI interfaces. Or I will try too. Getting technical info about Apple computers can be difficult because everyone in AppleLand seems to believe that there is no need for anyone to know "stuff like that" and that you would be better off just giving them $500 for a program that "take care of stuff like that". After all, that is what makes Apple so superior to everything else; the mindset goes.
Thanks again. I don't even know if the Gmega that I bought works since it was sold 'untested'. Everything that I have bought 'untested' on ebay has worked and usually well. It's just that it's difficult to actually tell if a tone module works if you don't have a MIDI keyboard or the original power supply. I actually prefer that people not try to get MIDI gear working. It's easy to break the power supply section since so few MIDI manufacturers believe that putting a ten cent diode between the power jack and the voltage regulator circuitry is a worthwhile investment on an $800 tone module. People might not buy their $39 matched wall-wart and get a $8 Radio Shack instead when the original tone module power convertor gets misplaced.
Oh, the joys of electronic repair...

--- On Wed, 12/16/09, GB wrote:
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From: GB
Subject: Re: [vintagesynthrepair] Re: to-host serial-to-MIDI port
To: vintagesynthrepair@yahoogroups.com
Date: Wednesday, December 16, 2009, 2:16 PM



> Alan, This is a Mac serial port and all are the same. Alesis, Korg, Roland, Yamaha, etc. Some will run at 115800 baud.... Fran

If that's true then you can find some info on the web for the mac interfaces. I've seen schematics for the Midiman Mini MacMan (r whatever it's called. Iwas actually looking for an RS232 to MIDI adapter and that's what I came up with.
I'm still looking for a cheap adapter that converts 32150baud RS232 level signals into the equivalent MIDI IN OUT.
GB



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