hi!
i want to have a couple of square oscillators (and some other stuff), but i have problems with the timing. this part of the code give me a square wave on pin 7 with variable frequency by connecting a potentiometer in analog0, but the 'resolution' of frequency is not enough, the max frequency is about 29khz (i have no problem with this) but the step to the next is too big (15khz - 10khz - 7khz, etc, the idea is to control it trough midi+cv), i want something more smooth. because that i want to use the TIMER0_COMPA_vect (as i understood the timer go until the number in OCR0A and generates the interrupt when done) seems easy to change the resolution of the frequency counter, but it don't change the frequency out on pin 7 when i put other number in OCR0A, the output of the pin 6 can vary from 31250 to 8Mhz but the frequency on 7 remains unchanged. anyone have an idea about this? thanks in advance, and i sorry for my bad english :~
#include <avr/pgmspace.h>
#include <avr/interrupt.h>
#include <pins_arduino.h>
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
//para el generador de frecuencia
int freq_1=100; // frecuencia osc 1
float t_high_1=1; // tiempo alto osc 1
int t_low_1=1; // tiempo bajo osc 1
int pot=0;
volatile byte icnt1; // var inside interrupt
volatile byte c4ms; // counter
boolean high_1=true; // determinacion del tiempo actual
boolean high_2=true; // en los dos osciladores
const int high_bit_7=B10000000; //salida de oscilador 1 en pin 7 puerto D
const int low_bit_7=B01111111;
const int high_bit_4=B00010000; //salida de oscilador 2 en pin 4 puerto D
const int low_bit_4=B11101111;
void setup() {
pinMode(5,OUTPUT); // pin5= PWM para correccion de la rampa 1 - timer 0 - OC0A
pinMode(6,OUTPUT);
pinMode(7,OUTPUT); // pin7= salida de frecuencia oscilador 1 PORTD7 - timer 1
pinMode(4,OUTPUT); // pin4= salida de frecuencia oscilador 2 PORTD4 - timer 1
cli();
Setup_timer0();
sbi (TIMSK0,OCIE0A); //habilita la interrupcion del timer 0 en compare match con OCR0A
sbi (TIMSK0,OCIE0B);
sbi (TIMSK0,TOIE0);
sei();
}
void loop () {
if (c4ms > 10) {
c4ms=0;
pot=analogRead(0)+20; // lee el potenciometro conectado en 0
freq_1=pot/5;
}
t_low_1=freq_1/2;
}
void Setup_timer0() {
// Timer0 Clock Prescaler to : 1
sbi (TCCR0B, CS20);
cbi (TCCR0B, CS21);
cbi (TCCR0B, CS22);
//modos de comparacion de los registros OCR
sbi (TCCR0A, COM0A0); // toggle pin 6 en Compare Match con OCR0A
cbi (TCCR0A, COM0A1);
sbi (TCCR0A, COM0B0); // toggle pin 4 en Compare Match con OCR0B
cbi (TCCR0A, COM0B1);
// Timer0 modo CTC
cbi (TCCR0A, WGM00);
sbi (TCCR0A, WGM01);
cbi (TCCR0A, WGM02);
}
ISR(TIMER0_COMPA_vect) {
OCR0A=145;
if (high_1==true){
PORTD = PORTD | high_bit_7;
t_high_1--;
if (t_high_1==0){
high_1=false;
t_high_1=t_low_1;
}
}
if (high_1==false){
PORTD = PORTD & low_bit_7;
t_high_1--;
if (t_high_1==0){
high_1=true;
t_high_1=t_low_1;
}
}
if (icnt1++ == 125) { // increment variable c4ms
c4ms++;
icnt1=0;
}
}
ISR(TIMER0_OVF_vect) {
}
