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ChordTrigger - Clockbased MIDI-Chord Slicer for VMC

chordtrigger.jpg

SQ-3P is a software to run on the VMC-system. It provides a MIDI step sequencer inspired by the sequencers in the Roland JX-3P and SH-101. The software is published as open source under the creative commons license 'by-nc-sa 4.0'

For the Installation please use the ARDUINO IDE, see https://www.arduino.cc/en/software. An introduction how to upload the program with the Arduino IDE can be found here.

ChordTrigger - Users Manual

Firmware Version 0.7
VMC-1 Hardware Version 1.5.4

THIS IS A BETA-VERSION

'ChordTrigger' is a programm for an Arduino Nano mounted on a “fanwander VMC-1'. The programm reads incoming MIDI-notes and sends them out according to a rhythm given either bei an internal or external clock, or by an internal synchronizable rhythm-sequencer. The velocity of the sent notes can be set manually, with an controllable random variation or by an additional velocity pattern with separate pattern length.

If your VMC-1 runs a different software at the moment, then please consult the programming instructions for the VMC-1 on how to install software. In this case you have to perform a 'Factory Reset' as described in the section 'setup menu'.
You should check the instruction for 'Adjust Poti-CVs' in the section 'setup menu'.

Quickstart...

...for those, who think they don't need manuals:
  • The function of the five buttons
     

    		 PLAY
    		 STOP
    		 WRITE
    		 F1
    		 F2
    Stop Mode
    		 Play
    		Write
    		 Enter Setup
    Display
    Play Mode
    		Stop
    		 Play Mode
    		 - reserved -
    Display Mode
    		 Velocity Mode
    Write Mode
    		 End & Play
    		 End & Stop
    		 Back
    		 Trigger Pattern
    		 Velocity Pattern
    Tie
    		 Rest

    		Setup Mode
    Select Param
    		 Exit Setup
    		 Edit
    		 < Parameter >
    Set Param

    		Set
    		 -- Value ++
     
  • Good Luck :-)
Now more details for the patient ones...

Connect and Configure the Hardware

This is described in the users manual of the VMC-1.

MIDI connections

Basically you need a device which sends MIDI-notes (I will call this 'the keyboard') and a device which can create sounds from MIDI-notes (I will call this 'the synth'). I will not explain how to connect MIDI devices. So establish the following MIDI connections
Keyboard-MIDI-Out <-> VMC-1-MIDI-In,
and
VMC-1-MIDI-Out <-> Synth-MIDI-In.

Usually you will get a VMC-1 with the ChordTrigger software loaded, and set to factory settings. To test with the factory settings of the ChordTrigger, set keyboard and synth to MIDI channel “1”.
For other settings please consult the description of the “setup menu”.

In STOP mode the keyboard should play the synth directly

Press PLAY, set the potentiometers of the VMC-1 to the center position and hold at least one key on the keyboard. The synth should play this note in a rhythmical pattern.

Generic Function

The ChordTrigger reads notes coming from the keyboard and stores them as a single chord as long as at least one key is pressed. If all keys have been released, the chord is regarded as completed and a new key-press will start a new chord. This chord will be played rhythmically. The according rhythm can be either a constant clock (internal or external); it can be a rhythm pattern stored internally; or it can be triggered by an external trigger signal, which may have its own pattern.

So let me first describe how to write the patterns:

WRITE - Create Patterns

The ChordTrigger has two separate patterns; one for the triggers, the other for the velocity modulation. I will first describe the trigger pattern and will explain the difference of the velocity pattern then.

To write a pattern for triggers or velocity the ChordTrigger must be in STOP mode.
  • Press the WRITE button.
    => the display says “F1=Trig F2=Vel”
  • If you want to write the pattern for the triggers, then press the F1 button (if you want to write the pattern for the velocity modulation, then press the F2 button).
    => the display says now either "WRITE T" for trigger pattern or "WRITE V" for the velocity pattern.
  • Now you can enter three possible values:
    • play one note on the keyboard for a trigger => a “+” (plus) will appear for each step in the lower line.
    • hit the F1 button to prolongating the trigger => a "-" (dash) will appear in the lower line
    • hit the F2 button for a pause => a "." (dot) will appear in the lower line
  • Hit STOP and then PLAY.
    => the display will show the entered sequence in the lower line. If you play now notes on the keyboard, you will hear the note played in the rhythm provided by the pattern (provided that you are still in the factory settings)
The WRITE-mode ends either if you hit STOP or PLAY or it ends automatically if you reach the limit of 64 steps.

The velocity pattern is written the same way as the trigger pattern, but you have to hit "F2" at the second step.
Similar as the trigger pattern, the velocity pattern is represented in the display by the characters  '+', '-', and '.' . In this case '+' is the highest value, '.' is the lowest value and '-' is the center between those two values.

PLAY - Triggering Chords

To get into the play mode press (surprise surprise...): PLAY. As already described: The ChordTrigger reads notes coming from the keyboard and stores them as a single chord. The chord will accumulated from the incoming note data until no key is pressed.

In play mode the display shows in the firstline something like this:

PLAY 3 1        
+-.+. 
  • The 'PLAY' (you allready guessed that) describes the mode.
  • The first number is the count of notes in the actual chord. In the example the current chord consists of three notes.
  • The second number is the count of actually pressed keys. If no key is pressed it is '0' (zero)
  • The +-.+. characters in the secondline represent the played steps. I will explain them later

There are several methods to enter a chord:
  • Play the chord on the keyboard as a piano player would do
  • Press and hold(!) the key for one note of the chord with one finger; then press with another  finger (of the other hand) the other notes of the chord one after the other. Then release the held note. The following example will enter a Cmaj7 chord:
    Right Hand: ....E...G..H.....
    Left Hand:  ..C----------....
    This way you may enter chords which spreads over the full keyboard range, and which a pianist never could play with two hands.
  • Play the chord broken, but overlapping legato. Again a Cmaj7 as example:
    .........H----.
    .......G----...
    ....E----......
    ..C---.........
The program handles a chord up to 12 notes (if required this number can be extended easily in the program code).
The chord generated this way will be played in several ways, depending on various mode settings:

Play Mode

There are two play modes.
  • Held
  • Keyed
In the held mode the incoming notes are handled as if a hold-pedal would be used with the keyboard. Even if you release all keys on the keyboard, the ChordTrigger will continue to play the last entered chord.

In the keyed mode the ChordTrigger will output the triggered notes only as long as one key on keyboard is pressed

While PLAY you can toggle between the two modes by pressing the WRITE button. The default play mode can be set in the setup menu.

Trigger Mode

There are two trigger modes:
  • Clock
  • Pattern
In the clock mode the chord will be repeated with each tick of the clock.

In the pattern mode the chord will be played accord to the rhythmic pattern that was entered in the 'WRITE' mode. The pattern consists of notes-steps, tie-steps (prolongates the former step to the next), and rest-steps.

The trigger mode can be set in the setup menu. It cannot be toggled directly while playing.

Velocity Mode

The ChordTrigger does not use the velocity of the incoming notes for the outgoing chord notes (I tried that, but - though I am a trained piano player - I did not find it very useful).
Since especially in clock mode the constantly repeating chords would become quite boring, there is the possibility to send the chord notes with variable velocity values. Of course this will have an effect only, if your synth can handle the velocity information. (It is planned to extend this feature to any CC or NRPN-value in a later version)
These variations of the velocity data can be created in four different modes:
  • Constant
  • Random
  • Pattern 0-1
  • Pattern -/+
In the constant mode the velocity is taken from the potentiometers CV-1 and CV-2. This way the velocity can be modulated by voltages via the inputs CV-1 and/or CV-2. Usually one will leave CV-1 without an external control voltage and use it as a generic setting and use CV-2 for the modulation. The resulting velocity is applied to all notes of the chord.

The random mode works basically like the constant mode, but a random value is added to the generic setting of CV-1. The amount of this random modulation is determined by CV-2. A voltage applied to the input CV-2 will not modulate the velocity directly, but will determine the range of this amount setting.
This random velocity level is provided for each note of the chord separately! Moderate amount settings will result in chord variations like an average trained piano player would create. Extrem settings can have results that remind more to a new sequence than to the original chord. (This note-individual modulation will not be possible for the planned CC or NRPN function)

In the two 'pattern' modes, the velocity can have three different values. Again CV-1 determines the base velocity. CV-2 determines the amount of the value changes caused by the pattern:
- in the mode Pattern 0-1' the pattern values are added to the base velocity,
- in the mode Pattern -/+' the '+'-values increase the base velocity, '.'-values decrease the base velocity. A '-'-value does not change the base velocity.
The velocity value is applied to all notes of the chord.
Since the velocity pattern can have a pattern length different to the trigger pattern, the results can be very complex.

STOP - to play or not to play

In the stop mode usually all incoming notes are forwarded to the output (including velocity). It is possible to deactivate this soft-thru-function in the setup menu.


Setup Mode

In the setup mode you configure the general behaviour of the ChordTrigger. You can enter the setup mode in play mode or in stop mode. In write mode the setup is not available.
  • To enter the setup menu press F1 and F2 together.
  • The display will change and list the actual parameter in the upper line. The lower line will display the actual value of the parameter.
  • To page through the parameters use F2 for “next” and F1 for “previous”. The setup starts always with “transpose mode”. For clock select, save sequence, or load sequence you may use the “previous”-function; for the note modes and channel settings you may use the “next”-function. You may step through all parameters in a circle in the both directions.
  • To change the value of a parameter press WRITE.
    => An exclamation mark (“!”) will appear at the start of the lower line to mark the EDIT mode.
  • Change the value with F1 (=decrease by one) and F2 (=increase by one). To change in larger steps you can use a combination of F1 and F2: Press and hold F1 and a short press on F2 will decrease by ten. Press and hold F2 and a short press on F1 will increase by ten.
  • Press WRITE again to leave the EDIT mode.
    => the value will be stored in the non volatile memory and the “!” disappears.
  • To leave the setup menu press PLAY and STOP together.
If you have entered the setup mode while the sequence was playing, the sequence will continue playing, but you cannot stop it in setup mode. You have to leave the setup mode to stop a playing sequence.
Since the internal clock is software created and the setup mode eats up a lot of processing, the internal clock will assumingly become a little slower.

List of the available Parameters:

  • 'ChordPlay Mode': determines when chords will be triggered .
  • 'Trigger Source': selects between the clock and the pattern as trigger source.
  • 'Velocity Mode': selects the type of velocity modulation.
  • 'Out-Channel': sets the MIDI channel on which the ChordTrigger sends its sequence.
  • 'In-Channel': sets the MIDI channel on which the ChordTrigger expects incoming note data.
  • 'Note-Thru': determines whether incoming notes are forwarded to the synth in the stop mode.
  • 'Control-Thru': sets whether incoming MIDI-ControlChange data are forwarded to the synth.
  • 'Program-Thru': sets whether incoming MIDI-ProgramChange data are forwarded to the synth.
  • 'Bend-Thru': sets whether incoming MIDI-Pitchbend data are forwarded to the synth.
  • 'OtherCh-Thru': sets whether MIDI-data on other channels than the out channel are forwarded to the MIDI out.
  • 'Adjust Poti-CVs': adopts the software for the real potentiometer values
  • 'Factory Reset': restores to the default parameter values and loads the test sequence
  • 'SaveSequence': saves the actual sequence in the EEPROM
  • 'LoadSequence': loads the sequence from the EEPROM
  • 'Clock': selects the clock source, and (MIDI-)clock division

Now the detailled desciption of the parameters

ChordPlay Mode

The ChordPlay Mode determines when chords will be triggered.
Value Comment
Held (Factory Default) As soon as one key has been pressed the chord will be played until the next chord is entered. The chord triggering will continue until STOP is pressed
Keyed Triggered chords will be sent only as long as at least one key is pressed.

This mode can be toggle while the play mode by wressing WRITE

Trigger Source

This selects the source of the triggers for the outgoing chords.
Value Comment
Pattern (Factory Default) The pattern triggers the outgoing chords
Clock The clock signal triggers the chord continuously (see also setup for "clock source"

Velocity Mode

This selects the type of velocity modulation for the outgoing chords
Value Comment
Constant
(Factory Default)		 The velocity for the outgoing chord is determined by both the potentiometers CV-1 and CV-2 and the corresponding control voltages respectively
Random
 A random value is added to the base value set by potentiometer CV-1. The amount of this random modulation is determined by CV-2. A voltage applied to the input CV-2 will not modulate the velocity directly, but will determine the range of this amount setting.
Pattern 0/+ The base value is set by potentiometer CV-1. Pattern values '-' are added half, pattern values '+' are added full. The amount of the pattern value addition is determined by CV-2
Pattern -/+ The base value is set by potentiometer CV-1. Pattern values '-' are subtracted from the base value, pattern values '+' are added to the base value. The amount of the pattern value addition / subtraction is determined by CV-2

Out Channel

The MIDI-channel on which the sequence and thru'ed Program/Control/Bend-data are sent out.
Value Comment
1 - 16
(Factory Default = 1)		 Pay attention if you are in playmode:

Changing the Channel while the sequence is playing or thru'ed notes are active will cause note hangs. In some special cases this may be wanted behaviour, so we did not prevent this.
To end these hangs while play mode switch back to the former channel, leave the setup mode and press TIE (the sequence will play on) or STOP (the sequence will stop).


In Channel

The MIDI-channel on which the ChordTrigger expects the data, that shall be written into the sequence.
Value Comment
0 = Out-Channel (Factory Default)
or
1 - 16		 Incoming MIDI data on the in-channel will be sent out on the out-channel. This is valid also for control, programchange, and pitchbend data!
It is recommended to deactivate OtherChannelThru if in-channel and out-channel are different.

The main intention for this feature is that you may have a single keyboard, but several ChordTriggers (or similar devices) in the thru chain. In that case you don't have to change the send channel on your keyboard, but simply use the out-channel on the ChordTrigger.
Otherwise we recommend to set the In-Channel the same as the Out-Channel.

Note Thru

This parameter determines under which condition note messages from the keyboard  (= on the in-channel) are forwarded to the synth (= on the out-channel) in stop mode.
Value Comment
Off Incoming note data are not forwarded in stop mode.
Thru while Stop
 Incoming note data will be forwarded while stop mode.

Control-Thru

Determines whether MIDI controlchange data from the keyboard (= in-channel) are forwarded to the synth (=out-channel)
Value Comment
On (Factory Default) see general comment regarding the thru modes below
Off

Program-Thru

Determines whether MIDI Programchange data from the keyboard (= in-channel) are forwarded to the synth (=out-channel)
Value Comment
On
see general comment regarding the thru modes below
Off (Factory Default)

Bend-Thru

Determines whether MIDI controlchange data from the keyboard (= in-channel) are forwarded to the synth (=out-channel)
Value Comment
On (Factory Default) see general comment regarding the thru modes below
Off



!!! Important Remark on Thru-Modes !!!

If you use the same device as keyboard and as synth then all those Thru-settings depend on your instrument.
If the instrument has a local-off mode, then you should activate this local-off mode and you should set all Thru-settings to “On” and the NoteThru not to “On”. For example my Rhodes Chroma Polaris in local off mode needs ControlThru and BendThru set to “On”. Otherwise the Chroma Polaris could not be edited. But ProgramThru has to be set to “Off”. Otherwise a MIDI-Loop on program change commands would happen and bring the whole MIDI-system to hang.
If the instrument has not(!) a local-off mode then you MUST set all Thru-settings to “Off”. Otherwise you would create an endless MIDI-loop which typically makes all processors overload and leave the system in unusable state, which typically can be solved only by switch off both the synth and the ChordTrigger. The same is valid if you use the ChordTrigger at the input and output of a MIDI-sequencer like Logic, Cubase, Ableton, Reaper, what ever…


OtherCh-Thru

Determines whether incoming MIDI data (no matter which type) in channels other than the out-channel are forwarded to the output.

Value Comment
On
A high MIDI traffic on other channels will affect the performance of the ChordTrigger since every data byte has to be handled by the processor. It even may cause the sequence to stutter or to stop. (Imagine an orchestras conductor who also has to hand out dishes from the kitchen while the concert all the time...)
Off (Factory Default)


Adjust Poti-CVs

Potentiometers are produced with a tolerance of 10% or even 20%. This function adopts the software to the individual potentiometers in this circuitry. This procedure has to be done after a factory reset.
Value Comment
no value - display reads:
Press Write		 After pressing WRITE a screen will be displayed like
SET POTIS TO MAX
!THEN PRESS WRITE
Turn the three potentiometers fully clockwise. Then press WRITE. The adjustment procedure will run automatically and display the potentiometer it is working on. Depending on the offset you will see the adjustment parameters counting up or down. Finally the display will read  'Tempo is good!' and switch on to the next knob. The display will switch to 'CV-1' and after some counting the display reads 'CV-1 is good!'. The display will switch to 'CV-2' finally, and after some couting the process will end with 'CV-2 is good!'.

If you did not set the potentiometers to the maximum before pressing WRITE the second time, then wrong offsetvalues will be stored. This won't harm the module electrically, but unwanted effects might happen on the MIDI-out. If this happens, simply repeat the procedure with the potentiometers set to maximum really.


The offset-values will be stored in the non-volatile EEPROM. So usually this procedure has to be called only once.



Factory Reset

Writes the factory default settings in the non-volatile EEPROM and loads them then into the runtime memory.
Value Comment
no value - display reads:
Press Write twice		 Press the WRITE button twice. The display will change to 'Reset EEProm', and then you will see the 'Load Pattern' display  (see below).

After the first WRITE you can cancel the Reset by pressing STOP.

This should not be done in PLAY mode. Hanging notes and other unwanted issues might occur.

Since the factory reset overwrites the settings of the potentiometer adjustment you have to redo the potentiometer adjustment.



Load Pattern

Loads the sequence stored in the non-volatile EEPROM into the runtime memory.
Value Comment
no value - display reads:
Press Write twice		 Press the WRITE button twice. You will see a short flicker, when the function counts the notes and steps.
Then the lower line reads “Load Done”.

After the first press on WRITE you can cancel the Load-action by pressing STOP.

Load should not be done in PLAY mode. Hanging notes and other unwanted issues might occur.

Save Pattern

Saves the sequence from the runtime memory in non-volatile EEPROM.

Value Comment
no value - display reads:
Press Write twice		 Press the WRITE button twice. You will see a short flicker, when the function counts the notes and steps.
Then the lower line reads “Save Done”.

After the first press on WRITE you can cancel the Save-action by pressing STOP.

Save may be done in PLAY mode, but the pattern may stumble if the save action takes longer than one step of the pattern.

Clock

Selects the clock source and the division factor, if the MIDI-clock is used. This setting is not stored in the internal memory. After switching off and on, always the internal clock is used.

Value Comment
Internal (Factory default) The internal clock generator is used. Neither MIDI-clock nor MIDI-start/stop commands are recognized
MIDI-clock 1/16 MIDI-clock is used with 16 triggers per 4/4-bar. MIDI-start/stop and(!) the internal START/STOP buttons are recognized. The pause function works only with the internal START-button
MIDI-clock 1/8 MIDI-clock is used with 8 triggers per 4/4-bar
MIDI-clock 1/4 MIDI-clock is used with 4 triggers per 4/4-bar
MIDI-clock 1/1 MIDI-clock is used with 1 trigger per bar
MIDI-clock 2/1 MIDI-clock is used with 1 trigger every second bar
MIDI Start/Stop Internal clock is used, but start and stop commands from MIDI are recognized
Attention! Do not change these settings while the chord trigger is running!






All product names and brand names beside “VMC-1”, ­“ChordTrigger” and “fanwander” belong to the corresponding owners. They are mentioned only for educational purposes.

All rights reserved, by Florian Anwander 2020 - 2022
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