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Author Topic: Struggling to get a photo cell to control velocity  (Read 489 times)
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Hi
 i am trying to write a piece of code to enable the control of velocity of a drum, i want to implement this control via a photo cell. i have adapted a piece of code to play 8 drum sounds in pro tools when a button is pressed. and i have a photo cell connected to cut the sound of certain drums completely. What i want to implement now is a control that can control the highhat peddles velocity through the  use of a photo cell. Any advice on this would be really appreciated.

Thanks smiley

this is the code below

// what midi channel we're sending on
// ranges from 0‐15
#define drumchan 9 // Equates to MIDI Channel 10
// general midi drum notes
#define note_bassdrum 36
#define note_snaredrum 38
#define note_clap 39
#define note_hihat 42
#define note_rim 45
#define note_openhat 46
#define note_hattype 51
#define note_horn 43
// define the pins we use
#define switchAPin 10
#define switchBPin 9
#define switchCPin 8
#define switchDPin 7
#define switchEPin 6
#define switchFPin 5
#define switchGPin 4
#define switchHPin 3
#define ledPin 13 // for midi out status
int switchAState = LOW;
int switchBState = LOW;
int switchCState = LOW;
int switchDState = LOW;
int switchEState = LOW;
int switchFState = LOW;
int switchGState = LOW;
int switchHState = LOW;
int currentSwitchState = LOW;
int val,t;
void setup() {
pinMode(switchAPin, INPUT);
pinMode(switchBPin, INPUT);
pinMode(switchCPin, INPUT);
pinMode(switchDPin, INPUT);
pinMode(switchEPin, INPUT);
pinMode(switchFPin, INPUT);
pinMode(switchGPin, INPUT);
pinMode(switchHPin, INPUT);
digitalWrite(switchAPin, HIGH); // turn on internal pullup
digitalWrite(switchBPin, HIGH); // turn on internal pullup
digitalWrite(switchCPin, HIGH); // turn on internal pullup
digitalWrite(switchDPin, HIGH); // turn on internal pullup
digitalWrite(switchEPin, HIGH); // turn on internal pullup
digitalWrite(switchFPin, HIGH); // turn on internal pullup
digitalWrite(switchGPin, HIGH); // turn on internal pullup
digitalWrite(switchHPin, HIGH); // turn on internal pullup
pinMode(ledPin, OUTPUT);
Serial.begin(57600); // set MIDI baud rate
}
void loop() {
// deal with switchA
currentSwitchState = digitalRead(switchAPin);
if( currentSwitchState == LOW && switchAState == HIGH ) // push
noteOn(drumchan, note_bassdrum, 100);
if( currentSwitchState == HIGH && switchAState == LOW ) // release
noteOff(drumchan, note_bassdrum, 0);
switchAState = currentSwitchState;
// deal with switchB
currentSwitchState = digitalRead(switchBPin);
if( currentSwitchState == LOW && switchBState == HIGH ) // push
noteOn(drumchan, note_snaredrum, 100);
if( currentSwitchState == HIGH && switchBState == LOW ) // release
noteOff(drumchan, note_snaredrum, 0);
switchBState = currentSwitchState;
// deal with switchC
currentSwitchState = digitalRead(switchCPin);
if( currentSwitchState == LOW && switchCState == HIGH ) // push
noteOn(drumchan, note_clap, 100);
if( currentSwitchState == HIGH && switchCState == LOW ) // release
noteOff(drumchan, note_clap, 0);
switchCState = currentSwitchState;
// deal with switchD
currentSwitchState = digitalRead(switchDPin);
if( currentSwitchState == LOW && switchDState == HIGH ) // push
noteOn(drumchan, note_hihat, 100);
if( currentSwitchState == HIGH && switchDState == LOW ) // release
noteOff(drumchan, note_hihat, 0);
switchDState = currentSwitchState;
// deal with switchE
currentSwitchState = digitalRead(switchEPin);
if( currentSwitchState == LOW && switchEState == HIGH ) // push
noteOn(drumchan, note_rim, 100);
if( currentSwitchState == HIGH && switchEState == LOW ) // release
noteOff(drumchan, note_rim, 0);
switchEState = currentSwitchState;
// deal with switchF
currentSwitchState = digitalRead(switchFPin);
if( currentSwitchState == LOW && switchFState == HIGH ) // push
noteOn(drumchan, note_openhat, 100);
if( currentSwitchState == HIGH && switchFState == LOW ) // release
noteOff(drumchan, note_openhat, 0);
switchFState = currentSwitchState;
// deal with switchG
currentSwitchState = digitalRead(switchGPin);
if( currentSwitchState == LOW && switchGState == HIGH ) // push
noteOn(drumchan, note_hattype, 100);
if( currentSwitchState == HIGH && switchGState == LOW ) // release
noteOff(drumchan, note_hattype, 0);
switchGState = currentSwitchState;
// deal with switchH
currentSwitchState = digitalRead(switchHPin);
if( currentSwitchState == LOW && switchHState == HIGH ) // push
noteOn(drumchan, note_horn, 100);
if( currentSwitchState == HIGH && switchHState == LOW ) // release
noteOff(drumchan, note_horn, 0);
switchHState = currentSwitchState;
// Send a MIDI note on message. L ‐ ike pressing a piano key
// channel ranges from 0‐15
}
void noteOn(byte channel, byte note, byte velocity) {
midiMsg( (0x90 | channel), note, velocity);
}
// Send a MIDI note‐off message. Like releasing a piano key
void noteOff(byte channel, byte note, byte velocity) {
midiMsg( (0x80 | channel), note, velocity);
}
// Send a general MIDI message
void midiMsg(byte cmd, byte data1, byte data2) {
digitalWrite(ledPin,HIGH); // indicate we're sending MIDI data
Serial.write(byte(cmd));
Serial.write(byte(data1));
Serial.write(byte(data2));
digitalWrite(ledPin,LOW);
}
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Have a look at this tutorial over at adafruit. Specifically, this page shows a) how to read the cell's voltage and b) how to use that to control the brightness of an LED using PWM.

The LED's brightness could be analogous to your volume, but I'll leave that part to you.  smiley-cool
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Thank you for the help smiley
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