Doepfer CTM64 Contact to Midi Interface (main board) - Manual (Page 4)

page 4 CTM64 Version 4 - User's Guide
Introduction
CTM64 is an universal MIDI Out kit. Up to 64 free contacts can be connected to generate MIDI note
on/off or program change messages. CTM is suitable to retrofit keyboards, switch panels, button
arrangements or any other contacts so that they are able to transmit MIDI data. Up to 4
potentiometers can be connected to generate common MIDI controllers, pitch bend and after
touch. Additionally a 1/4 jack socket is available for connecting a sustain pedal.
Two different modes are selected with the first of 8 jumpers: note on/off or program change. In the
note mode closing of a contact generates the corresponding MIDI note on message, opening generates
note off - both without velocity (velocity is fixed to 100). In the program change mode closing of a
contact leads to the corresponding MIDI program change message.
The note offset (i.e. the MIDI note number assigned to the first contact) can be set to 0 or 36 with the
second jumper. With two more jumpers one can transpose up/down one octave, i.e. +12/-12 semitones.
Instead of these jumpers a 3-position switch (1-0-1) working as an octave switch can be soldered to
the corresponding pins of the jumper pin header. In this way the note offsets 0, 12, 24, 36 and 48 are
available. If another note offset (e.g. 41) is required the contacts are displaced correspondingly and the
unused contact terminals are left free.
In the program change mode the offset can be set to 1 or 64, i.e. setting the program number range to
1-64 or 65-128 (0-63 or 64-127 in MIDI code). With two daisy-chained CTM64 the whole program
number range 1...128 is covered.
The 4 potentiometer plugs are used to connect up to 4 potentiometers (e.g. rotary, slider, wheels or
others) generating the MIDI messages pitch-bend, modulation (controller #1), volume (controller
#7) and monophonic after touch.
The 1/4“ jack socket can be used to insert a sustain pedal (contact type ”closed at rest” is required)
generating the MIDI sustain message (controller #64).
The MIDI channel for all messages transmitted by the CTM64 is set with the last 4 jumpers.
The 64 contacts are connected to four double row pin headers with 16 pins each. 16 pin socket-
connectors (female) with flat cable can be connected to these pin headers (not included with the
CTM64). Additionally there is one common pin for all contacts. Pay attention that only free contacts can
be used. This means that the contacts are not allowed to be connected with another electronics or
connected with a fixed voltage (e.g. GND).
For the potentiometer four male pcb connectors with 3 pins (GND, slider, +5V) are available. Suitable
female connectors with assembled cables can be connected to these pin headers (not included with the
CTM64).
CTM64 is equipped with MIDI In and MIDI Out. The incoming MIDI messages are merged to the data
generated by the CTM64. In this way several CTM64 can be linked together (e.g. 3 CTM64 required
for 2 keyboards with 61 keys and one basepedal with 32 keys, or switch boards with more than 64
switches).
CTM64 is available only as an assembled and tested pc board. The pc board measures are about 90
x 105 mm. Four mounting holes with 3 mm diameter are available for mounting the pc board to a
suitable base e.g. with distance sleeves or spacers and screws.
The configuration of CTM64 (i.e. MIDI channel, mode, note offset and so on) is made by the customer
with 8 jumpers - as described above.