 |
| Fig.1 - Reassigned percussion and chorus pushbuttons on the XB5 |
In Part 4 I showed how NRPN messages from the XB5 organ can be decoded to control parameters in the B4000+ sound module using CC messages. In this post we look at controlling the effects using the XB5s pushbuttons, e.g. vibrato, chorus, percussion (2nd & 3rd harmonic) etc.
For some of the controls is was fairly straightforward to simply determine which XB5 button was pressed then change the appropriate B4000+ parameter accordingly, e.g. bass pedal sustain. However, the percussion and vibrato/chorus controls were more tricky as the ergonomics are different in both cases.
Vibrato/chorus
The XB5 has a control for selecting either vibrato or chorus and another for selecting depth of effect (using two buttons). The B4000+ just uses one control to select type (vibrato or chorus) and depth. This is shown in the table below.
To make things simpler I decided to leave out the vibrato functions (V1, V2 & V3) as I never use those sounds. Therefore I only needed the two buttons for depth (both buttons are activated for depth 3). This left a spare button which I repurposed as a MIDI all-notes-off function (see below).
Percussion
The XB5 allows you to switch on/off 2nd harmonic and 3rd harmonic percussion independently. The B4000+ has a control for turning percussion on/off and another control which sets the harmonic (a range of harmonics are available, not just 2nd or 3rd). I decided to repurpose the “2nd” button to switch percussion on/off and the “3rd” button to switch between 2nd or 3rd harmonic (see Fig.1).Case Statements
Rather than using multiple “if” statements for decoding the different push-buttons, I used “switch” and “case” statements, which is more elegant from a programming perspective.
Switch statements have the syntax:
switch (expression) {
case constant 1: statement sequence 1;
break;
case constant 2: statement sequence 2;
break;
.
.
.
case constant N: statement sequence N;
break;
}
The switch works by checking the expression against the constants. If a match is found, that sequence of statements is executed. If the statement sequence associated with the matching case does not contain a break, execution will continue on into the next case (Schildt, 2003).
I implemented the pushbutton remapping in the Arduino code and used MIDI-OX for testing and debugging, before confirming correct operation with the XB5 and B4000+. A snippet of the resulting code is shown below.
void handleMidiEventControlChange(byte inChannel, byte inControlNumber, byte inControlValue)
{
if (inControlNumber!=5) //Use this to filter out a given CC message
{
if (inControlNumber==92)
{
inControlNumber=4; //Change CC number for Leslie speed control
}
if (inControlNumber==99)
{
NRPNcode = inControlValue;
NRPNflag = 1; //Set flag to indicate that an NRPN message has been recieved
}
if (inControlNumber==6)
{
// Process NRPN message
data = inControlValue;
if (NRPNflag==1)
{
//Check NRPN code
switch (NRPNcode)
{
case 9: //Is it Leslie on/off?
inControlNumber=83;
inControlValue=data;
break;
case 23: //Is it vibrato upper?
inControlNumber=50;
inControlValue=data;
break;
case 24: //Is it vibrato lower?
inControlNumber=49;
inControlValue=data;
break;
case 11: // Vibrato/chorus button?
// XB5 uses a seperate NRPN message to switch between vibrato & chorus
// whereas B4000+ uses a single CC message for V1,V2,V3,C1,C2,C3.
// Simpler to remove option to switch from chorus to vibrato and repurpose
// XB5 vibrato/chorus button for something else.
inControlNumber=123; // All notes off
inControlValue=0;
break;
case 69: //Is it vibrato/chorus mode 1,2,3?
// Use this to just to switch between C1, C2 & C3.
if (data==32) // V1/C1
{
inControlNumber=51;
inControlValue=0; // C1
}
if (data==64) // V2/C2
{
inControlNumber=51;
inControlValue=2; // C2
}
if (data==96) // V3/C3
{
inControlNumber=51;
inControlValue=4; // C3
}
break;
case 8: //Is it pedal sustain?
if (data==0) // Sustain off
{
inControlNumber=103;
inControlValue=0; // Release=0
}
if (data==127) // Sustain on
{
inControlNumber=103;
inControlValue=95; // 75% release
}
break;
case 18: // Percussion ON/OFF - Repurposing of 2nd harmonic button
inControlNumber=40;
inControlValue=data; // Switch percussion ON/OFF
break;
case 19: // 2nd/3rd harmonic? - Repurposing of 3rd harmonic button
inControlNumber=37;
if (data==0) // 2nd percussion?
{
inControlValue=57; // Harmonic=2nd
}
if (data==127) // 3rd percussion?
{
inControlValue=68; // Harmonic=3rd
}
break;
case 21: // Soft percussion?
inControlNumber=38;
if (data==0)
{
inControlValue=27; // 79% percussion level
}
if (data==127) // Soft percussion?
{
inControlValue=63; // 50% percussion level
}
break;
case 22: // Fast percussion decay?
inControlNumber=39;
if (data==0) // Slow decay?
{
inControlValue=42; // 33% decay
}
if (data==127) // Fast decay?
{
inControlValue=0;
}
break;
}
}
NRPNflag = 0; //Reset NRPN flag
}
if ((inControlNumber==80)||(inControlNumber==81)||(inControlNumber==82)) //Check if it is drawbar setting
{
index = (inControlNumber-80)*81 + inControlValue;
inControlNumber = byte1[index];
inControlValue = byte2[index];
}
MIDI.sendControlChange(inControlNumber, inControlValue, inChannel);
}
}
While testing software there have been occasions when a rogue note-on message has been generated, thus causing a note to be stuck on. I suspected this was just due to glitches/latency from using a ‘software’ serial port. This is addressed in the next installment of this blog, but for convenience I added a MIDI all-notes-off function using a (now) spare XB5 push-button (see above).
Continued in Part 6.
Reference
Schildt, Herbert (2003), “C/C++ Programmer’s Reference”, published by McGraw-Hill/Osborne.
Disclaimer: This is my personal blog. Views expressed in my posts are my own and not of my employer. The information provided comes with no warranty. I cannot be held responsible for the content of external websites. Any practical work you undertake is done at your own risk. Please make health and safety your number one priority.
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