37 lines
1.2 KiB
C
37 lines
1.2 KiB
C
|
|
// ------- Preamble -------- //
|
|
#include <avr/io.h> /* Defines pins, ports, etc */
|
|
#include <util/delay.h> /* Functions to waste time */
|
|
#include <avr/interrupt.h>
|
|
#include <avr/power.h>
|
|
#include "pinDefines.h"
|
|
#include "macros.h"
|
|
#include "fullSaw15.h"
|
|
|
|
#define BASEPITCH 220 /* in tuningWord steps, which are ~1/2 Hz */
|
|
#define PHASE_RATE 7 /* controls speed of phasing effect */
|
|
|
|
#define NUMBER_OSCILLATORS 4
|
|
/* 2 and 4 work just fine.
|
|
8 and 16 take too long to maintain our 31.25kHz sample rate
|
|
so the pitch shifts downwards and there's all sorts of aliasing.
|
|
If you're just after scary sounds, 8 and 16 are awesome, but you may want
|
|
to increase the BASEPITCH to compensate. */
|
|
|
|
#define OSCILLATOR_SHIFT 2
|
|
/* This is the number of bits to shift when volume mixing.
|
|
2**OSCILLATOR_SHIFT = NUMBER_OSCILLATORS
|
|
If you don't change this to match the number of oscillators, you'll
|
|
get clipping and digital distortion. */
|
|
|
|
|
|
static inline void initTimer0(void){
|
|
set_bit(TCCR0A, WGM00); /* Fast PWM mode */
|
|
set_bit(TCCR0A, WGM01); /* Fast PWM mode */
|
|
|
|
set_bit(TCCR0A, COM0A1); /* PWM output on OCR0A */
|
|
set_bit(SPEAKER_DDR, SPEAKER); /* enable output on pin */
|
|
|
|
set_bit(TCCR0B, CS00); /* Clock with /1 prescaler */
|
|
}
|