Users Manual - VMC-System / VMC-1

!!! PRE RELEASE DRAFT Hardware!!!


Features


The VMC-1 is an euro rack module which provides

  • an Arduino Nano board which does all the digital data handling
  • a backlit display with 16 characters in two rows. The display cannot provide graphics.
  • five buttons, which are scanned by the Arduino board. The labels are:
    • PLAY
    • STOP
    • WRITE
    • F1 (=function 1)
    • F2 (=function 2)
    • The real function of all those buttons depends on the software loaded to the Arduino
  • three potentiometers:
    • TEMPO: this potentiometer provides 0 - +5V Volt DC to the Arduino
    • CV1: this potentiometer provides the voltage coming from the input CV1 to the Arduino.  As the socket CV1 is normalled to +5V the potentiometer will provide 0 - +5V Volt DC to the Arduino if nothing is inserted in the socket.
    • CV2: this potentiometer provides the voltage coming from the input CV2 to the Arduino.  As the socket CV2 is normalled to +5V the potentiometer will provide 0 - +5V Volt DC to the Arduino if nothing is inserted in the socket.
  • five input sockets:
    • PLAY: a digital input that executes the same function as the Play button. 0 Volt = button not pressed; 5 - 12 Volt = button is pressed.The usual threshold is around +2V.
    • STOP: a digital input that executes the same function as the Stop button. 0 Volt = button not pressed; 5 - 12 Volt = button is pressed. The usual threshold is around +2V.
    • CLOCK: a digital input that is read by the Arduino. The switching contact of the socket is connected to a digital output of the arduino. So an external signal can replace a signal which is generated internally by the Arduino. 0 Volt = digital low; 5 - 12 Volt = digital high. The usual threshold is around +2V.
    • CV1: a control voltage input that is fed to the potentiometer CV1. The evaluated voltage ranges from 0 Volt to about +5V. The input is limited internally by a Zenerdiode; higher input voltages won't damage the module but will have no effect.
    • CV2: a control voltage input that is fed to the potentiometer CV2. The evaluated voltage ranges from 0 Volt to about +5V. The input is limited internally by a Zenerdiode; higher input voltages won't damage the module but will have no effect.
The module will not do anything as long as you do not upload a suitable software to the Arduino board. Uploading software is described in the the file programming_instructions_vmc-1.html


Setting up the module




Define the powersupply


As first step you have to define by jumpers which power supply line is used:
  • Your eurorack does not provide +5V, so you use the +12V line:



    If you use a 9V wallwart powersupply, then you must choose this setting too.
    (Wallwart powersupply is only optional available for the kit version).

  • Your eurorack does provide a +5V line. Then set it like that:



Connection the VMC-1 with the Input/Output-Modules

To be useful the VMC module must be connected to a MIDI-in/out Module like the fanwander MIDI-ITO. The connection is provided by a ten way flat cable, the VMC-bus. The orientation of the cable is important. The cable must be placed with the red strip directing to the marking at the pin header:



Select the IO configuration


The VMC-Bus provides three busses of MIDI-In/Out. You have to select by jumpers on which bus your VMC-1 module is listening. The standard-setting is "bus 1" for both directions:



If you use a MIDI-ITO module for the MIDI-connections you have to configure the same bus lines with the jumpers on the MIDI-ITO module:



If you use multiport modules like the MIDI-3IT and the MIDI-OOO respectively then no jumper settings are required on those modules.

Connect the VMC-1 with the power supply bus

Power off your euro rack system!

Connect the VMC-1 with the 16-fold ribbon cable to the supply-bus of your euro rack system. The orientation of the cable is important. The cable must be placed with the red strip directing to the marking at the pin header:



ATTENTION: on the first pcb series, the writing -12/+12/+5 is printed at the wrong position due to an unhappy accident. Don't obey these. The correct pinout is shown below:







This is a preliminary manual. It is based on prototypes only. Requirements of the final hardware may cause changes in the described use.

All product names and brand names beside "VMC-1", "SQ-3P" and "fanwander" belong to the corresponding owners. They are mentioned only for educational purposes.

All rights reserved, by Florian Anwander 2020 - 2021