Contol Pitch in semitone By usb midi cc#

Using Arduino Programming Questions
1

i am trying to control Master pitch by 1 semitone on each step of my plugin by cc#100 at channel 1, as you will
see here in my code .
as i am seeing a midi cc# value(0-127) = totel 128 units. so i tried it with 2 methods
-----------Method 1________
i set my knob range to 12.
when pitch knob at center pitch=0,
when fully rotated to left pitch= -1200cents,
when fully rotated to left pitch = +1200 cents .
so totel steps are 24 .
i think 1 step interval will be .... 128/24 =5.33.
so i declared variable (semi_key) multiply with 5.33 to get pitch inc/dec by 100cents/1semitone.
i thought when semi_key =12; , it will do knob to center & get pitch=0.
and chenge pitch in semitones , as i will inc or dec semi_key
and i use code this

float semi_key = 12.00;
float Pitch_cc = 63.00;
void loop() {
 if (c == 25)     {  if (semi_key > 0) { semi_key--;        
                              Pitch_cc = ((5.33*semi_key)-1);   
                              controlChange(1,100, Pitch_cc);  
                                MidiUSB.flush();    }}
  if (c == 26)     {  semi_key =12.00;                        
		Pitch_cc = ((5.33*semi_key)-1);   
		  controlChange(1,100, Pitch_cc);   
		MidiUSB.flush();   }  
   if (c == 27)     {  if (semi_key < 24) {semi_key++;   
		 Pitch_cc = ((5.33*semi_key)-1);   
		  controlChange(1,100, Pitch_cc);  
		 MidiUSB.flush();   }}
                      
}

but it got result ,,

when semi_key=0 , getting pitch = -28cents , instead of 0 ......(28 cents up)
when semi_key is increased from 0 . getting +85 . instead of +100 .....(15 cents less)
when decreased from 0 . getting pitch =-123 . instead of -100....(23 cent 0ver)

Method 2 ----

i set my knob range to 16
when pitch knob at center pitch=0,
when fully rotated to left pitch= -1600cents,
when fully rotated to left pitch = +1600 cents .
so totel steps are 32.
i think 1 step interval will be .... 128/32 =4.
so i declared variable (semi_key) multiply with 4 to get pitch inc/dec by 100cents/1semitone.
i thought when semi_key =16; , it will do knob to center & get pitch=0.
and chenge pitch in semitones , as i will inc or dec semi_key
and i use code this

float semi_key = 16.00;
float Pitch_cc = 63.00;
void loop() {
 if (c == 25)     {  if (semi_key > 0) { semi_key--;        
                              Pitch_cc = ((4*semi_key)-1);   
                              controlChange(1,100, Pitch_cc);  
                                MidiUSB.flush();    }}
  if (c == 26)     {  semi_key =16.00;                        
		Pitch_cc = ((4*semi_key)-1);   
		  controlChange(1,100, Pitch_cc);   
		MidiUSB.flush();   }  
   if (c == 27)     {  if (semi_key < 32) {semi_key++;   
		 Pitch_cc = ((4*semi_key)-1);   
		  controlChange(1,100, Pitch_cc);  
		 MidiUSB.flush();   }}
                      
}

but it got result ,,

when semi_key=0 , getting pitch = -13 cents , instead of 0 ......(13 cents up)
when semi_key is increased from 0 . getting +88 . instead of +100 .. (12 cents less)
when decreased from 0 . getting pitch =-113 instead of -100 ......(13cents over)

in both Metods am not getting accurate pitch changes . where am i doing mistake??????

2

It seems to be mostly a series of truncation errors. Rounding instead of truncating should help some. Using 5.333333 instead of 5.33 might also help.

3

Even better, let the compiler give you the best possible number, use

Pitch_cc = ((128.0/24.0*semi_key)-1);

And since the controlChange function takes a byte (0-255) value, round it

Pitch_cc = ((128.0/24.0*semi_key)-1)+0.5;
4

And you might as well change "Pitch_cc" to an integer type. I would use 'byte' since the allowed range is 0 to 127.

5

Thanks you all,
But reply became tuka , not working.
I seemed midi cc value not support decimal number. I tried 63.5 . But not support. It need Real numbers.
So thank you , I will use jugaad code as my sense(will have to accept +15 or -15 cents near correct pitch) like 212 as 200 ,. 788 as 800,. 508 as 500.

In which 0 will give -1200 , and 127 will give +1200 , 63 will give -9
.....

6

Don't use 7-bit Control Change messages to change the pitch, use 14-bit Pitch Bend messages for higher resolution.

1 Like
7

My slave pitch knob is from beat tracks. I can't assign pch Bender function. If use this, it Will also affect my playable sounds's or Selected plug ins pitchs . I was searching for cc for control separately from pitch Bender. Thank you Peter for help reply

8

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