Arduino AM Transmitter

 

 https://www.instructables.com/AM-Transmitter-With-Arduino/

 https://www.youtube.com/watch?v=Xy7DiPVi18Y

 

 

/*
 Name:        transmitter.ino
 Created:    11/13/2019 7:48:39 PM
 Author:    michael
*/

#define ANTENNA_PIN PB3 //Arduino Nano/Uno D11

// the setup function runs once when you press reset or power the board
void setup() {
    Serial.begin(115200);

    //Carrier Frequency generation
    uint32_t fTransmit = 600; //KHz
    DDRB |= (1 << ANTENNA_PIN);
    TCCR2A = (0 << COM2A1) + (1 << COM2A0); //Toggle OC0A on Compare Match
    TCCR2A |= (1 << WGM21) + (0 << WGM20); //CTC
    TCCR2B = (0 << CS22) + (0 << CS21) + (1 << CS20); //No Prescaling
    OCR2A = F_CPU / (2000 * fTransmit) - 1;
    
    char strbuf[255];
    sprintf(strbuf, "Will broadcast at %d KHz", (F_CPU / (2 * (1 + OCR2A)) / 1000));
    Serial.println(strbuf);

    //PWM Signal generation
    //TCCR1A |= (0 << WGM11) + (1 << WGM10);  //Fast PWM 8 Bit
    //TCCR1A |= (1 << WGM11) + (0 << WGM10);  //Fast PWM 9 Bit
    TCCR1A |= (1 << WGM11) + (1 << WGM10); //Fast PWM 10 Bit
    TCCR1B = (1 << WGM12);                   
    TCCR1B |= (0 << CS12) + (0 << CS11) + (1 << CS10); //No Prescaling
    TIMSK1 = (1 << OCIE1A) + (1 << TOIE1);

    //ADC Settings
    ADMUX = (1 << REFS1) + (1 << REFS0); //Reference internal 1.1V
    ADCSRA = (1 << ADEN) + (1 << ADSC) + (1 << ADATE); //Auto Trigger enable, free running
    ADCSRA |= (1 << ADPS2) + (1 << ADPS1) + (0 << ADPS0); //Divide by 64 -> 18.5k Sample rate
    DIDR0 = (1 << ADC0D);
}

ISR(TIMER1_OVF_vect) {
    uint8_t adcl = ADCL;
    uint8_t adch = ADCH;
    OCR1A = (adch << 8) + adcl;
    DDRB |= (1 << ANTENNA_PIN);
}

ISR(TIMER1_COMPA_vect) {
    DDRB &= ~(1 << ANTENNA_PIN);
}

void loop() {
}