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:



ATTENTION: the labeling for IN and OUT is swapped on the PCB imprint of the first series. The jumpers next to the supply voltage selection are responsible for the MIDI-IN. The jumpers in the direction of the buttons for the MIDI-OUT.
You can recognize the first series by the imprint "VMC-1 V1.5.4 ©florian anwander, 2020-2021". Beginning with version 1.5.5 the labeling is correct.


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: