Hi, I'm struggling with getting my code to work, I'm using the circuit from the arduino frequency detection instructable and I have managed to get it to pick up frequencies fine but what I was hoping to do was get the arduino to detect the frequency and then send a MIDI message so the note would play.
Any help would be greatly appreciated as I'm a bit stumped.
Here is the code I'm using:
//clipping indicator variables
boolean clipping = 0;
//data storage variables
byte newData = 0;
byte prevData = 0;
unsigned int time = 0;//keeps time and sends vales to store in timer[] occasionally
int timer[10];//sstorage for timing of events
int slope[10];//storage fro slope of events
unsigned int totalTimer;//used to calculate period
unsigned int period;//storage for period of wave
byte index = 0;//current storage index
float frequency;//storage for frequency calculations
int maxSlope = 0;//used to calculate max slope as trigger point
int newSlope;//storage for incoming slope data
//variables for decided whether you have a match
byte noMatch = 0;//counts how many non-matches you've received to reset variables if it's been too long
byte slopeTol = 3;//slope tolerance- adjust this if you need
int timerTol = 10;//timer tolerance- adjust this if you need
//for MIDI instructions
int noteON = 144;//144 = 10010000 in binary, note on command
int noteOFF = 128;//128 = 10000000 in binary, note off command
int velocity = 100;
void setup(){
Serial.begin(9600);
pinMode(13,OUTPUT);//led indicator pin
pinMode(12,OUTPUT);//output pin
cli();//diable interrupts
//set up continuous sampling of analog pin 0 at 38.5kHz
//clear ADCSRA and ADCSRB registers
ADCSRA = 0;
ADCSRB = 0;
ADMUX |= (1 << REFS0); //set reference voltage
ADMUX |= (1 << ADLAR); //left align the ADC value- so we can read highest 8 bits from ADCH register only
ADCSRA |= (1 << ADPS2) | (1 << ADPS0); //set ADC clock with 32 prescaler- 16mHz/32=500kHz
ADCSRA |= (1 << ADATE); //enabble auto trigger
ADCSRA |= (1 << ADIE); //enable interrupts when measurement complete
ADCSRA |= (1 << ADEN); //enable ADC
ADCSRA |= (1 << ADSC); //start ADC measurements
sei();//enable interrupts
}
ISR(ADC_vect) {//when new ADC value ready
PORTB &= B11101111;//set pin 12 low
prevData = newData;//store previous value
newData = ADCH;//get value from A0
if (prevData < 127 && newData >=127){//if increasing and crossing midpoint
newSlope = newData - prevData;//calculate slope
if (abs(newSlope-maxSlope)<slopeTol){//if slopes are ==
//record new data and reset time
slope[index] = newSlope;
timer[index] = time;
time = 0;
if (index == 0){//new max slope just reset
PORTB |= B00010000;//set pin 12 high
noMatch = 0;
index++;//increment index
}
else if (abs(timer[0]-timer[index])<timerTol && abs(slope[0]-newSlope)<slopeTol){//if timer duration and slopes match
//sum timer values
totalTimer = 0;
for (byte i=0;i<index;i++){
totalTimer+=timer[i];
}
period = totalTimer;//set period
//reset new zero index values to compare with
timer[0] = timer[index];
slope[0] = slope[index];
index = 1;//set index to 1
PORTB |= B00010000;//set pin 12 high
noMatch = 0;
}
else{//crossing midpoint but not match
index++;//increment index
if (index > 9){
reset();
}
}
}
else if (newSlope>maxSlope){//if new slope is much larger than max slope
maxSlope = newSlope;
time = 0;//reset clock
noMatch = 0;
index = 0;//reset index
}
else{//slope not steep enough
noMatch++;//increment no match counter
if (noMatch>9){
reset();
}
}
}
if (newData == 0 || newData == 1023){//if clipping
PORTB |= B00100000;//set pin 13 high- turn on clipping indicator led
clipping = 1;//currently clipping
}
time++;//increment timer at rate of 38.5kHz
}
void reset(){//clea out some variables
index = 0;//reset index
noMatch = 0;//reset match couner
maxSlope = 0;//reset slope
}
void checkClipping(){//manage clipping indicator LED
if (clipping){//if currently clipping
PORTB &= B11011111;//turn off clipping indicator led
clipping = 0;
}
}
void loop(){
checkClipping();
frequency = 38462/float(period);//calculate frequency timer rate/period
//print results
Serial.print(frequency);
Serial.println(" hz");
//MIDI notes
int Enote = 40;
int Fnote = 41;
int Fsnote = 42;
int Gnote= 43;
if (frequency>79&frequency<84.5) {
MIDImessage(noteON, Enote, velocity);
}
else {
MIDImessage(noteOFF, Enote, velocity);
}
if (frequency>84.6&frequency<89.5) {
MIDImessage(noteON, Fnote, velocity);
}
else {
MIDImessage(noteOFF, Fnote, velocity);
}
if (frequency>89.6&frequency<95) {
MIDImessage(noteON, Fsnote, velocity);
}
else {
MIDImessage(noteOFF, Fsnote, velocity);
}
if (frequency>95.1&frequency<101) {
MIDImessage(noteON, Gnote, velocity);
}
else {
MIDImessage(noteOFF, Gnote, velocity);
}
}
//send MIDI message
void MIDImessage(int command, int MIDInote, int MIDIvelocity) {
Serial.write(command);//send note on or note off command
Serial.write(MIDInote);//send pitch data
Serial.write(MIDIvelocity);//send velocity data
}
