MIDI

Autor: Piotr Podkowinski (ppodkow_at_ire.pw.edu.pl)
Data: Fri 06 Sep 1996 - 17:34:16 MET DST

Macie - znalazlem u siebie cos takiego:

The MIDI adaptor connecting to the joystick port of the Sound Blaster
Pro card can be made from $10' s worth of components. I implemented
the following schematic (without THRU):

Midi Out/In/Through Circuit
===========================

      MIDI OUT port ---->| |<---- MIDI IN port +5V
                                                      +5V 270 |
            +5V(pin 1) DIN DIN 8 +--\/\/\/-+
             | 220 +-+ +-+ 220 2+----+---+6|
             +-\/\/\/--|4| |4|--\/\/\/--| OPTO |-+-+- UART RXD
SBPro | | | | |ISOLATOR| |(SBPro pin 15)
TXD - pin 12 --\/\/\/--|5| |5|----------| |-+ |
                220 | | | | 3+--------+5| |
                    +--|2| |2| 6N138 GND|(pin 4 or 5)
                    | +-+ +-+ |
                   GND |
                                                               |
                   +-------------------------------------------+
                   |
                   | +5V DIN
                   | | 220 +-+
                   | |\ +-\/\/\/--|4|
                   | | \ | |
                   +--| \---\/\/\/--|5| MIDI THRU
                      | / 220 | |
                      | / +--|2|
                      |/ 7407 | +-+
                                 GND

The MIDI OUT connection is particularly simple: except for two resistors
it is just a straight connection from the joystick D-type connector to
the 5-pin MIDI Socket. The pinouts are as follows:

        +5V GND GND +5V
         8 7 6 5 4 3 2 1
 +-----/-------------------------------\-----+
 | \ o o o o o o o o / |
 | ( ) \ / ( ) |
 | \ o o o o o o o / |
 +--------\-------------------------/--------+
           15 14 13 12 11 10 9
      UART Rx Tx

The MIDI IN interface is a bit more involved: You need to build a
small PCB with the optoisolator circuit shown above. I did not get
the MIDI IN to work until I connected the Soundcard's GND to the
computer casing (earth). This should not be necessary, but I don't
know why it didn't work without it (anyone?).

The MIDI RxD signal is very sensitive, so good layout is needed
(short open leads, etc...), and you may have to experiment with
different values of the resistors.

Obviously, I cannot assume responsibility for the correctness of
this information or any damage caused.

Andreas 

---
=============================================================================
| Piotr Podkowinski jr. |    ppodkowinski_at_elka.pw.edu.pl   |  A1230/10/1.2G |
|   student IAiIS PW    | http://www.ia.pw.edu.pl/~s142073 |i486_at_120/16/1.2G|
=============================================================================
		God is real ... unless declared integer.

To archiwum zostało wygenerowane przez hypermail 2.1.7 : Tue 18 May 2004 - 12:53:46 MET DST