61 lines
1.1 KiB
C
61 lines
1.1 KiB
C
#include <stdint.h>
|
|
#include <stdbool.h>
|
|
#include <avr/io.h>
|
|
#include <avr/interrupt.h>
|
|
#include "avr.h"
|
|
|
|
#define cbi(byt, bit) (byt &= ~_BV(bit))
|
|
#define sbi(byt, bit) (byt |= _BV(bit))
|
|
|
|
extern volatile bool tick;
|
|
extern volatile uint32_t jiffies;
|
|
|
|
// Count microseconds
|
|
volatile uint32_t micros = 0;
|
|
|
|
// Interrupt called every 1024 µs
|
|
SIGNAL(TIMER0_OVF_vect)
|
|
{
|
|
uint32_t m = micros;
|
|
|
|
m += 1024;
|
|
if (m >= JIFFY_uS) {
|
|
m %= JIFFY_uS;
|
|
tick = true;
|
|
jiffies += 1;
|
|
}
|
|
micros = m;
|
|
}
|
|
|
|
|
|
#define mode(on) bit(PORTD, _BV(0), on)
|
|
#define sin(on) bit(PORTD, _BV(1), on)
|
|
#define sclk(on) bit(PORTD, _BV(2), on)
|
|
#define xlat(on) bit(PORTD, _BV(3), on)
|
|
// Connect GSCLK to SCLK
|
|
// Connect BLANK to XLAT
|
|
// TRUST ME, THIS TOTALLY WORKS
|
|
|
|
#define nesclk(on) bit(PORTD, _BV(4), on)
|
|
#define nesltch(on) bit(PORTD, _BV(5), on)
|
|
#define nesout() ((PIND & _BV(6)) << 6)
|
|
|
|
void
|
|
init(void)
|
|
{
|
|
// Set timer 0 interrupt clock divider to 64
|
|
TCCR0B = 0x03;
|
|
|
|
// enable timer 0 overflow interrupt
|
|
TIMSK0 = 0x01;
|
|
|
|
// Enable interrupts
|
|
sei();
|
|
|
|
DDRD = ~(_BV(NESOUT));
|
|
DDRB = 0xff;
|
|
|
|
PORTD = 0;
|
|
|
|
}
|