106 lines
4.2 KiB
C++
106 lines
4.2 KiB
C++
// High-frequency PWM using Timer2 on pins 3 & 11
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const int pwmPin1 = 11; // OC2B
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const int pwmPin2 = 3; // OC2A
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bool readADC2 = true;
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void setup() {
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pinMode(pwmPin1, OUTPUT);
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pinMode(pwmPin2, OUTPUT);
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// ----- Timer2 Fast PWM (8-bit), no prescaler -----
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TCCR2A = _BV(WGM20) | _BV(WGM21) | _BV(COM2A1) | _BV(COM2B1); // Fast PWM mode, enable PWM on Pin 11, enable PWM on Pin 3
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//TCCR2B = _BV(CS20); // No prescaler → 16MHz / 256 = 62.5 kHz
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TCCR2B = _BV(CS21); // Prescaler 8 → (16MHz / 8) / 256 = 7.812 kHz
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ADCSRA = (1 << ADEN) | (1 << ADPS2); // Set ADC prescaler to 16 (1MHz ADC clock), 13 cycles to read a value so a readout takes 13 uS
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// Atmel/Microchip recommends:
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// 50–200 kHz for full 10-bit accuracy
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// Up to 1 MHz for reduced accuracy (≈ 8–9 bits)
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Serial.begin(9600);
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}
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int currentSense2 = 0;
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int currentSense3 = 0;
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int countdownOffPWM1 = 1024;
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int countdownOffPWM2 = 1024;
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void loop() {
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//int adc0 = analogRead(A0);
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ADMUX = (1 << REFS0) | (A0 & 0x0F); // Set ADC reference to AVcc and channel to ADC channel 0, example REFS0 = 1 → 0100 0000 | Channel 3 → 0000 0011 | ADMUX → 0100 0011
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ADCSRA |= (1 << ADSC); // Start ADC conversion
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while (ADCSRA & (1 << ADSC))
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; //wait or the ADC conversion to finish
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int adc0 = ADC;
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//int adc1 = analogRead(A1);
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ADMUX = (1 << REFS0) | (A1 & 0x0F); // Set ADC reference to AVcc and channel to ADC channel 0, example REFS0 = 1 → 0100 0000 | Channel 3 → 0000 0011 | ADMUX → 0100 0011
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ADCSRA |= (1 << ADSC); // Start ADC conversion
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while (ADCSRA & (1 << ADSC))
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; //wait or the ADC conversion to finish
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int adc1 = ADC;
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if (adc0 <= 100) { //Because the controller has noise on the ADC reading below this value and we want the cars to be still in position.
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adc0 = 0;
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}
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if (adc1 <= 100) { //Because the controller has noise on the ADC reading below this value and we want the cars to be still in position.
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adc1 = 0;
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}
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uint8_t pwm1 = map(adc0, 0, 1023, 0, 255);
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uint8_t pwm2 = map(adc1, 0, 1023, 0, 255);
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if (countdownOffPWM1 == 1024) {
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OCR2B = pwm1; // Output is LOW from 0 to pwm1 value (between 0 and 256) and then goes HIGH from pwm1 value to 255 on Pin 3
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} else {
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countdownOffPWM1 = countdownOffPWM1 - 1;
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if(countdownOffPWM1 == 0){
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countdownOffPWM1 = 1024;
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TCCR2A |= _BV(COM2A1); // Reconnect PWM to pin 11
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}
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}
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if (countdownOffPWM1 == 1024) {
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OCR2A = pwm2; // Output on pin 11 TCCR2A |= _BV(COM2B1);
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}
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else {
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countdownOffPWM2 = countdownOffPWM2 - 1;
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if(countdownOffPWM2 == 0){
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countdownOffPWM2 = 1024;
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TCCR2A |= _BV(COM2B1); // Reconnect PWM to pin 3
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}
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}
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if (readADC2) { //Every two cycle we read ADC2 and ADC3
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//int adc2 = analogRead(A2);
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while (TCNT2 < 217); // wait until timer 2 is 20uS from resetting to perform the ADC conversion in 13 cycles thus in 13uS
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ADMUX = (1 << REFS0) | (A2 & 0x0F); // Set ADC reference to AVcc and channel to ADC channel 0, example REFS0 = 1 → 0100 0000 | Channel 3 → 0000 0011 | ADMUX → 0100 0011
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ADCSRA |= (1 << ADSC); // Start ADC conversion
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while (ADCSRA & (1 << ADSC)); //wait or the ADC conversion to finish
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currentSense2 = ADC;
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if(currentSense2 > 128){
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countdownOffPWM1 = 1023;
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TCCR2A &= ~_BV(COM2A1); //Disable PWM from pin 11
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PORTB &= ~_BV(PB3); // Pin 11 = PB3, force pin 11 LOW
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}
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readADC2 = false;
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} else {
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//int adc2 = analogRead(A3);
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while (TCNT2 < 217); // wait until timer 2 is 20uS from resetting to perform the ADC conversion in 13 cycles thus in 13uS
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ADMUX = (1 << REFS0) | (A3 & 0x0F); // Set ADC reference to AVcc and channel to ADC channel 0, example REFS0 = 1 → 0100 0000 | Channel 3 → 0000 0011 | ADMUX → 0100 0011
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ADCSRA |= (1 << ADSC); // Start ADC conversion
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while (ADCSRA & (1 << ADSC)); //wait or the ADC conversion to finish
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currentSense3 = ADC;
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if(currentSense3 > 128){
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countdownOffPWM2 = 1023;
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TCCR2A &= ~_BV(COM2B1);; //Disable PWM from pin 3
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PORTD &= ~_BV(PD3); // Pin 3 = PD3, force pin 3 LOW
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}
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readADC2 = true;
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}
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} //end main loop
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