MDBC16x9
16*9 MIDI drawbar controller.
  (Design for Money)
---------------------------
  by Jordan D. Petkov

The archive file MKC.ZIP contains a set of files:

README.TXT   - this file;
MDBC16x9.JPG - electrical schematic of device;

1.About schematic.

Minimum elements are used to achieve minimal cost:  

U1:PIC16C84 - the famous single-chip controller by Microchip is 
   the core of this device;

U2:74LS138  - decoder 3-to-8, used to scan keyboard dynamically; 

Q1-4MHz,C2,C3: quartz resonator and capacitors needed for PIC's 
   internal clock generator;

R1,R2: resistors to pull up a specific IC pins to Vcc (which is +5v);

R3: protective resistor;

Diodes: generic Si diodes. One diode per drawbar is enough since there can be
only one closed contact on a single drawbar (i.e. scan matrix point crossing on
single drawbar is not possible);

Drawbars: these are 9-position sliding switches by original. Rotary
switches can also be used.

Connector DB 15 (male) - to connect to soundcard MIDI/Game port.

No need of power supply for this unit since it is powered directly by PC 
Game/MIDI port. Thus a most dangerous element in such devices (a power 
supply unit) is avoided. 

This device is intended for working with PC sound boards only. If you
wish to use it with another MIDI stuff, you should think about power
supply and buffering MIDI signals in standard way as described
in many articles I have seen in Internet.

2.About firmware.

Since this is Design for Money only pre-programmed chips coiuld be ordered.
For more details about ordering see project's homepage (link at the document bottom).

Supported are up to 16 drawbars generating MIDI Controls as follows:

Drawbar #:		MIDI control #:
----------		---------------
 1 			user defined
 2			user defined
 3			user defined
 4			user defined
 5			user defined
 6			user defined
 7			user defined
 8			user defined
 9			user defined
10			user defined
11			user defined
12			user defined
13			user defined
14			user defined
15			user defined
16			user defined

Each drawbar has 9 positions. Each MIDI control cah have value 0..127. 
Here is shown default drawbar positions mapping over control values:

Drawbar position #	Control value
------------------	-------------
0			000 ($00)
1			010 ($0A)
2			030 ($1E)
3			045 ($2D)
4			060 ($3C)
5			078 ($4E)
6			099 ($63)
7			114 ($72)
8			127 ($7F)

NOTE: The values mapping above is subject to change on customer demand.

------------------

3.Ordering pre-programmed chip.

Go to project's homepage:
www.geocities.com/jdpetkov/hardware/mdbc16x9 


j.d.petkov@mailcity.com
www.geocities.com/jdpetkov