Side-Tone Generator für PCW Fistcheck

Für das reglmässige Gebe-Training mit der Hand-Taste ist für die Nutzung mit PWC-Fistcheck
(Ernst F. Schroeder DJ7HS https://www.qsl.net/dj7hs/download.htm) ein Side-Tone Generator mit zwei Ausgängen enstanden.

/*
  CW Side-Tone genarator with adjustable frequency and two outputs (One for head-phones and one for PC-SoundCard
  The code has been written to train Morse-Code with straight key and check with Precision CW Fistcheck 
  From Ernst F. Schroeder DJ7HS see https://www.qsl.net/dj7hs/download.htm
  
  December 2018 Kai DM3KB
 */
 
// Analog Pins
//
int potPin = 0;    // input pin for the potentiometer A0 Hardware Pin 19

// Digital Pins
//
int         tonePin  = 10;       // Tone output to headphone pin D10 Hardware Pin 13
int         outpin   = 5;        // Tone output to PC pin D05  Hardware Pin 8
int         keyin    =  6;       // Input from Key pin D06  Hardware Pin 9
int         led      = 13;       // LED Pin D13 Hardware Pin 16

// Declare Variables
int val = 0;       // variable to store the value read from the potentiometer
int wave = 1;     // variable to flag half wave
int timerstat = 0; // Timer Status Flag 
int playflag = 0; //  Play Tone Flag
int ledstat = 0;  //  LED Status Flag
unsigned long LTCNT1;    // variable for Timer1 pre-set to match of halve-wave of a frequency


void setup()
{
  // initialize the digital pin as an output.
  pinMode(tonePin, OUTPUT); // declare the tonePin as an OUTPUT
  pinMode(outpin, OUTPUT); // declare the outpin as an OUTPUT
  pinMode(led, OUTPUT);  // declare the ledPin as an OUTPUT  
  
  // Setup control input pins
  pinMode(keyin, INPUT);       
  
  // Setup control output pins
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
 
  // Timer 1, set up to enable Overflow interrupt after 65536 with prescale 1
  noInterrupts();           // Switch of all Interrupts 
  TCCR1A = 0;               // set entire TCCR0A register to 0
  TCCR1B = 0;               // set entire TCCR0B register to 0
  TCNT1 = 39168;            // Pre-Inizialize the Timer1
  TCCR1B |= (0 << CS12) | (0 << CS11) | (1 << CS10); // set 1 as Prescale-Wert
  TIMSK1 |= (1 << TOIE1);   // Activate Timer Overflow Interrupt 
  interrupts();             // Enable all Interrupts again
  
  //Serial.begin(9600);      // open the serial port at 9600 bps:
}

// Interrupt -andler for 
// Timer1 Overflow
ISR(TIMER1_OVF_vect)        
{
  TCNT1 = LTCNT1;             // Init counter again with actual value from Poti          
  if (playflag == 1) {
    // If play Flag valid (1) play 
    // square-wave to both output pins with timing read from Potentiometer which meet the frequency
    if (wave == 1) {
      //Play positive wave part
      digitalWrite(tonePin, HIGH);
      digitalWrite(outpin, HIGH);
    }
    else {
      //Play negative wave part
      digitalWrite(tonePin, LOW);
      digitalWrite(outpin, LOW);
    }
  }
  wave = !wave;   // Toggel wave Flag 
}

// The (Main) loop routine runs over and over again forever:
void loop()
{
  // Check if Key is pressed
    if (digitalRead(keyin)== LOW){
    wave = 1;
    while(digitalRead(keyin)== LOW){
      // As long key in is LOW (Key is pressed so we need an output!!!) 
      // Enable Interrupt
     
      if (timerstat == 0 ) {
        //Serial.print(" = : Enable Interupt Play\n");
        playflag = 1;
        timerstat = 1;
      }
      if ( ledstat == 0 ) {
        digitalWrite(led, HIGH);    // turn the LED on by making the voltage HIGH
        ledstat = 1;
      }
      // Read tone frequency from Poti and map to sutialbe values
      val = analogRead(potPin);    // read the value from the sensor
     
      // TCNT1 is the pre-set for the timer to start.
      // So Timer1 will count starting from 39168 or 55625 or any value in between and creating an 
      // Overflow Interrupt when reaching 65536
      // I needs to be set to time that a halve wave of the frequency need.
      // Formula is here: 65536 - (65536 - 16000000 / 1 / 350 / 2)
      //                  Max Value of Timer  - ( Max Value of Timer / Arduino Clock Rate / PreScale / Frequency in Hz / 2 )
      LTCNT1 = map(val, 0, 1023, 39168, 55625);  //Map to value for TCNT1: 350 Hz = 39168 - 1250 Hz = 55625
    
      // Generate square-wave to both output pins with frequency read from Potentiometer
      // by Timer1 Interrupt routine ISR(TIMER1_OVF_vect)  
      
    }
  }
  
    if (digitalRead(keyin)== HIGH){
    while(digitalRead(keyin)== HIGH){
      // Key has bee released so no output
      if ( timerstat == 1 ) {
        //Serial.print(" = : Disable Interrupt Play\n");
        playflag = 0;
        timerstat = 0;
      }
      wave = 0;
      // But check Speed-Potentiometer
      val = analogRead(potPin);    // read the value from the sensor
      LTCNT1 = map(val, 0, 1023, 39168, 55625);  //Map to value for TCNT1: 350 Hz = 39168 - 1250 Hz = 55625
      
      if ( ledstat == 1 ) {
        digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
        ledstat = 0;
      }
    }
  }
}
// End