I am trying to make a program that generates sin-waves that i will output through a passive summer and thus make the microcontroller play sounds when i press buttons.
I have got the PWM to work, and can play notes using constant values, but I would like to use Sin-waves instead of constants.
Heres the code that ive come up with so far:
#include <pic32mx.h>
#include <stdint.h>
extern void _enable_interrupt();
//Change length of the Steps.
#define step 0.00000000000000000001
struct Note{
int number;
int freq;
double A;
double x;
int play;
}Note;
struct Note array[12];
void gen(int i){
float pi = 3.141592;
double x = array[i].x;
double freq = array[i].freq;
double A = sin(freq*x*step*2*pi);
x++;
array[i].A = A;
array[i].x = x;
}
void initNotes(){
struct Note C = {0, 200, 0.0, 0.0, 0};
struct Note Ciss = {1, 200, 0.0, 0.0, 0};
struct Note D = {2, 200, 0.0, 0.0, 0};
struct Note Diss = {3, 4100, 0.0, 0.0, 0};
struct Note E = {4, 3900, 0.0, 0.0, 0};
struct Note F = {5, 3700, 0.0, 0.0, 0};
struct Note Fiss = {6, 3500, 0.0, 0.0, 0};
struct Note G = {7, 3300, 0.0, 0.0, 0};
struct Note Giss = {8, 3100, 0.0, 0.0, 0};
struct Note B = {9, 2900, 0.0, 0.0, 0};
struct Note Biss = {10, 2700, 0.0, 0.0, 0};
array[0] = C;
array[1] = Ciss;
array[2] = D;
array[3] = Diss;
array[4] = E;
array[5] = F;
array[6] = Fiss;
array[7] = G;
array[8] = Giss;
array[9] = B;
array[10] = Biss;
}
void initSynth() {
for(;;) {
int btns = getBtns();
// Check buttons. If button is pressed, corresponding note's play-value will be set to 1 (true)
if((PORTD & 0b000000100000) == 0b000000100000){
array[0].play = 1;
}else{
array[0].play = 0;
}
if((PORTD & 0b000001000000) == 0b000001000000){
array[1].play = 1;
}
else{
array[1].play = 0;
}
if((PORTD & 0b000010000000) == 0b000010000000){
array[2].play = 1;
}else {
array[2].play = 0;
}
// Check note-array for notes with play-value 1 (true). These are added together.
int c;
int nr;
int i;
for(i = 0; i < 11; i++){
if(array[i].play == 1){
c = c + array[i].A;
gen(i);
nr++;
}
}
// Set PWM to previously calculated value.
if((c/nr) > 0){
setPwm((c/nr), 50);
} else setPwm(0,0);
}
}
int getBtns(void) {
return((PORTD >>5) &0x7); /* Port D bits 5 through 8 is used for the Buttons and is set to 1 (input) */
}
int getSwitches(void) {
return((PORTD>>8) &0xF); /* Port D bits 8 through 12 is used for the Switches and is set to 1 (input) */
}
int getbtn(void) {
return(PORTD &0x1);
}
void initPwm(){
T2CON = 0x070; // Clear timer2, prescale at 1:1
TMR2 = 0x0; // Timer2 value starts at 0
OC1CON = 0x0000; // Turn off and clear pwm
OC1R = 0x0001;
OC1RS = 0; // Dutycycle
OC1CON = 0x0006; // Configure for PWM mode without Fault pin
PR2 = 0; // Set dutycycle, HÄR ÄNDRAR MAN TONER!
IECSET(0) = 0x0100; // Enable T2 interrupt
IPCSET(2) = 0x01C; // Set T2 interrupt priority to 7
enable_interrupt();
OC1CONSET = 0x08000; // Enable OC1
T2CONSET |= 0x08000; // Enable Timer2
}
void setPwm(int pwm, int duty){
int dutycycle = 0xFFFFFFFF * (duty / 100);
OC1RS = duty;
PR2 = pwm;
}
int main(void) {
TRISE = 0x00; /* Port E bits 0 through 7 is used for the LED and is set to 0 (output) */
PORTE = 0x00;
initNotes();
initPwm();
initSynth();
return 0;
}
void user_isr( void ) {
if((IFS(0)&0x0100)==0x0100){
IFSCLR(0) = 0x0100;
}
}
When i press the button the summer starts to buzz and tick at different speed each time i press the button. Sometimes I get clean tones, so I get the feeling that I am somewhat close to a solution. Is the problem that the computer runs at an alternating speed? Maybe the solution is adding another timer somewhere?
