/*
 PWM Clock: Simple clock for analog synth modules.
 One potentiometer controls the speed (Freq) and the other controls the sustain/length of the pulse (PWM).
 
 
 
 
 Pulse:
 5v     _____________       _____________
 |     |             |     |             |
 |     |             |     |             |
 |     |             |     |             |
 |_____|_____________|_____|_____________|__
 0         1         2         3         4 
 
 
 
 
 Note: The freq knob must be wired in reverse:
 5+  - pin1
 A0  - pin2 (W)
 0+  - pin3
 */

const int led = 13;
const int freqPin = 0;                       // 10k revese log potentiometer
const int pwmPin = 1;                        // 10k log potentiometer
const int tempoMin = 30;                     // The minimum tempo 30bpm = 2se
enum {sample_state,high_state,low_state};    //Enumerate(give values to) the variables so they are 0,1,2 respectivly
unsigned int state = sample_state;
unsigned int val1,val2,val3,hiVal,loVal;
float timer;
double mVal = 0;
double bpm = 30;
 
/*----------------------------------------Main loop--------------------------------------*/
void setup() {
        Serial.begin(9600);
        pinMode(13,OUTPUT);
}
 
void loop() {
        switch(state){                                                   //There are 3 different states that take place, take sample from inputs, set high duration, set low duration
                case sample_state:
                        val1 = analogRead(pwmPin);
                        val2 = 1023 -analogRead(pwmPin);
                        val3 = analogRead(freqPin);
 
                        mVal = map(val3,0,1023,60,2000);                //Mapped from 60-2000millisec
                        hiVal = map(val1,0,1023,0,mVal);
                        loVal = map(val2,0,1023,0,mVal) +1;
                       
                        bpm = (2000 / mVal) * tempoMin;                 // tempoMin = 30
                        Serial.print(bpm) ;
                        Serial.print(" :BPM    ");
                       
                        state = high_state;                             //We have inputs, next we go on to high state mode
                        digitalWrite(led,HIGH);                         //Set the pin high as the next state is just a timer
                        timer=millis();                                 //Set timer to the time when this code block finishes
                        break;
                case high_state:                                                                       
                        if(millis()>=timer+hiVal){                      //Sit in this state until the timer threshold reaches the end of the high state       
                          state=low_state;                              //Move on to low state tmer
                          digitalWrite(led,LOW);                        //Set pin low
                          timer=millis();                               //Reset timer
                        }
                        break;
                case low_state:                        
                        if(millis()>=timer+loVal){                      //Sit in this state until the timer threashold reaches end of the low state
                          state=sample_state;                           //Cycle completed, go back to taking a new sample and repeat cycle
                        }
                        break;
                default:                                                //This should never happen
                        Serial.println("state variable not valid");
                        while(1);
                        break;
        }
        
}