How to use Port 2 of GVP IO Extender for Midi
---------------------------------------------

WARNING:

If you don't have any soldering or electronics experience then
stop now, you'll need to be able to solder to perform this hack.

I accept no responsability for damages caused by performing this
hack.


Parts you need:

17x2 square connector socket (to connect to option connector)
5x2  square connector socket (to connect to port 2 connector)
25 way male D connector.

All connections will be made to a standard 25 way serial socket,
this allows a normal serial port midi interface to be connected.

ATTENTION:

if you use IDC cable (ribbon cable) for this hack and you intend
to split the cables then solder them together, bear in mind that
the wires are interleaved eg. for the 5x2 connector the sequence
is:

1st cable
|
|  2nd cable etc...
|  |
v  |
1  v  2     3     4     5
   6     7     8     9


I find IDC cable easier, you need less soldering and there's less
chance of short circuits. Also, if you can buy some, use heat shrink
sleeving to insulate the solder joints, it's neater than tape and
doesn't leave a sticky mess.

----------------------------------------------------------------
                   Connector 1 17x2


 Layout of the option connector on the IO extender as viewed
 from above.
                           /- notch
 ________________________ V________________________
|33 31 29 27 25 23 21 19 17 15 13 11 09 07 05 03 01|
|34 32 30 28 26 24 22 20 18 16 14 12 10 08 06 04 02|
 --------------------------------------------------


You need to source the +12v and -12v signals from this
connector, the standard 9 pin serial port does not carry
these power lines.

pin 27 carries the -12v, connect this to pin 10 of the 25 way D
pin 25 carries the +12v  connect this to pin 9 of the 25 way D
----------------------------------------------------------------
                   Connector 2 5x2

Layout of the 2nd serial port connector on the edge of the
IO extender. This is the view looking down onto the connector
on the board.

      /- notch
     V
 ­­­­ ­­­­
|5 4 3 2 1|
|- 9 8 7 6|
 ŻŻŻŻŻŻŻŻŻ

You need to connect the Receive, Transmit and System ground
connections of the 25 way


 2 = Receive, connect this to pin 3 of the 25 way D
 3 = Transmit, connect this to pin 2 of the 25 way D
 5 = System ground, connect this to pin 7 of the 25 way D
----------------------------------------------------------------
that's all you need to do.

I will be writing Bars and Pipes midi input and output tools
to support this hack soon, so look forward to 32 midi channels
and two midi Inputs! (no need for midi merger now)

any program using midi.library will be patchable to the GVP by
selecting the IOExtender as serial and unit 1 in the GVPIOControl
program.

recommended programs using midi.library:

Midiplay    - midi file player
XGEdit      - my editor for Yamaha DB50XG/QS300

both are on aminet, have fun.

If you want me to make you a cable, then i'm open to offers, I won't
charge excessively, but i've got to cover my costs and pay for my time.

email: jg750616@stmail.staffs.ac.uk