User manual

MIDI KEYBOARD CMK-2 MIDI SPECIFICATION MANUAL v1.5
20 2009 CLASSIC ORGAN WORKS CMK-2 Manual 1.5.doc
MIDI Hardware Specification
[1]
The only MIDI connector approved by the MIDI Manufacturers Association is a 5-pin 180º DIN connector. There are
other ways of connecting devices to send MIDI messages but it is easier to have compatibility between different MIDI
devices if there is a standard connector. In connecting a MIDI device to a personal computer, the simplest way is
through the MIDI ports of a computer (MIDI connectors are uni-directional from the ‘OUT’ connector to the ‘IN’
connector). Due to space limitations of computer circuit boards, most computers are not equipped with a MIDI port.
Thus, adapters must be used that connect the MIDI device to another port. The most common port is the computer’s
game port that is found on most soundcards. Adapters are also available for the serial port, parallel port, and USB port.
A schematic of the 5-pin DIN connector typical interface is shown below: The basic signal is a negative-going pulse
on pin-5.
Figure 10: 5-pin DIN connections
MIDI Hardware NOTES:
1. Opto-isolator shown is Sharp PC-900. HP 6N138 or other types can be used with changes.
2. Gates ‘A’ are Integrated Circuit or transistor; Resistors are 5%.
3. Maximum cable length is fifty feet (15 meters), terminated at each end by a 5-pin 180º DIN male plug (e.g. SWITCHCRAFT
05GM5M).
4. Cable is shielded twisted-pair, with shield connected to pin 2 at both ends.
5. MIDI In ground is not connected (to avoid Ground Loops).