Просмотр сообщений
1
Джойстики и прочие манипуляторы / Восстановление геймпада (клона) от Sega Mega Drive 2
« : 28 Январь 2026, 22:36:06 »
Прочитав статьи по данной тематике, как например здесь и при помощи ИИ, мне удалось написать код на С который легко можно залить через Arduino Nano по SPI.
Для разработки и заливки решил использовать Platformio. Теперь хочется ревью от более опытного программиста, кто мог бы указать на баги.
Для разработки и заливки решил использовать Platformio. Теперь хочется ревью от более опытного программиста, кто мог бы указать на баги.
Код: [Выделить]
/*
* Sega Mega Drive / Genesis controller
* 3-button + proper 6-button extension
*
* MCU: ATmega8 / ATmega88
* Clock: 8 MHz (internal)
*/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdbool.h>
#include <stdint.h>
/* ================= Sega DB9 mapping =================
*
* PD2 UP / X
* PD3 DOWN / Y
* PD4 LEFT / Z
* PD5 RIGHT / MODE
* PD6 A / B
* PD7 START / C
*
* PB7 TH / SELECT (input from console)
*
* All outputs are ACTIVE LOW
*/
/* ================= Button source =================
* Replace these macros with your real button inputs
* Note: Buttons are assumed to be active-low (pressed = LOW)
*/
#define BTN_UP() ((PINB & (1 << PB0)) == 0)
#define BTN_RIGHT() ((PINB & (1 << PB1)) == 0)
#define BTN_DOWN() ((PINB & (1 << PB2)) == 0)
#define BTN_LEFT() ((PINB & (1 << PB3)) == 0)
#define BTN_START() ((PINB & (1 << PB4)) == 0)
#define BTN_A() ((PINB & (1 << PB5)) == 0)
#define BTN_B() ((PINC & (1 << PC0)) == 0)
#define BTN_C() ((PINC & (1 << PC4)) == 0)
#define BTN_MODE() ((PINC & (1 << PC5)) == 0)
#define BTN_X() ((PINC & (1 << PC3)) == 0)
#define BTN_Y() ((PINC & (1 << PC2)) == 0)
#define BTN_Z() ((PINC & (1 << PC1)) == 0)
/* ================= Internal state ================= */
static volatile uint8_t phase = 0;
static volatile uint8_t isSix = 0;
static volatile uint8_t prevTH = 1;
static volatile uint8_t idleTicks = 0;
/* ================= Helpers ================= */
static inline void writeLo(uint8_t pin)
{
PORTD &= ~(1 << pin);
}
static inline void writeHi(uint8_t pin)
{
PORTD |= (1 << pin);
}
static inline uint8_t th_level(void)
{
return (PINB & (1 << PB7)) ? 1 : 0;
}
/* ================= Timer0 overflow (~1 ms) ================= */
#if defined(__AVR_ATmega8__)
ISR(TIMER0_OVF_vect)
#else
ISR(TIMER0_COMPA_vect)
#endif
{
/* Increment idleTicks atomically */
uint8_t ticks = idleTicks;
ticks++;
idleTicks = ticks;
if (ticks > 12) {
/* Disable interrupts to prevent race condition with main loop */
cli();
phase = 0;
isSix = 0; /* fallback to 3-button */
sei();
}
}
/* ================= TH polling ================= */
static inline void sega_poll_th(void)
{
uint8_t th = th_level();
if (th != prevTH) {
prevTH = th;
idleTicks = 0;
/* Disable interrupts to prevent race condition with ISR */
cli();
uint8_t p = phase;
if (++p >= 8) {
p = 0;
isSix = 1; /* successful 6-button detect */
}
phase = p;
sei();
}
}
/* ================= Sega output ================= */
static inline void sega_output(void)
{
uint8_t th = th_level();
/* release all lines */
writeHi(PD2); writeHi(PD3); writeHi(PD4);
writeHi(PD5); writeHi(PD6); writeHi(PD7);
/* ---------- 3 BUTTON MODE ---------- */
if (!isSix) {
if (th) {
BTN_B() ? writeLo(PD6) : writeHi(PD6);
BTN_C() ? writeLo(PD7) : writeHi(PD7);
} else {
BTN_UP() ? writeLo(PD2) : writeHi(PD2);
BTN_DOWN() ? writeLo(PD3) : writeHi(PD3);
BTN_LEFT() ? writeLo(PD4) : writeHi(PD4);
BTN_RIGHT() ? writeLo(PD5) : writeHi(PD5);
BTN_A() ? writeLo(PD6) : writeHi(PD6);
BTN_START() ? writeLo(PD7) : writeHi(PD7);
}
return;
}
/* ---------- 6 BUTTON MODE ---------- */
switch (phase) {
case 0:
case 1:
case 2:
if (!th) {
BTN_UP() ? writeLo(PD2) : writeHi(PD2);
BTN_DOWN() ? writeLo(PD3) : writeHi(PD3);
BTN_LEFT() ? writeLo(PD4) : writeHi(PD4);
BTN_RIGHT() ? writeLo(PD5) : writeHi(PD5);
}
break;
case 3:
if (th) {
BTN_B() ? writeLo(PD6) : writeHi(PD6);
BTN_C() ? writeLo(PD7) : writeHi(PD7);
} else {
BTN_A() ? writeLo(PD6) : writeHi(PD6);
BTN_START() ? writeLo(PD7) : writeHi(PD7);
}
break;
case 4:
/* 6-button ID phase */
writeLo(PD2); writeLo(PD3);
writeLo(PD4); writeLo(PD5);
break;
case 5:
if (!th) {
BTN_X() ? writeLo(PD2) : writeHi(PD2);
BTN_Y() ? writeLo(PD3) : writeHi(PD3);
BTN_Z() ? writeLo(PD4) : writeHi(PD4);
BTN_MODE() ? writeLo(PD5) : writeHi(PD5);
}
break;
case 6:
case 7:
/* These phases are not used in 6-button mode output */
/* Controller should be idle during these phases */
break;
}
}
/* ================= Main ================= */
int main(void)
{
/* Disable ADC (digital I/O only) */
ADCSRA &= ~(1 << ADEN);
/* PD2–PD7 outputs */
DDRD |= (1 << PD2) | (1 << PD3) | (1 << PD4) |
(1 << PD5) | (1 << PD6) | (1 << PD7);
/* TH input (PB7) - no pull-up needed, console drives it */
DDRB &= ~(1 << PB7);
/* Button inputs: PB0-PB5 */
DDRB &= ~((1 << PB0) | (1 << PB1) | (1 << PB2) | (1 << PB3) | (1 << PB4) | (1 << PB5));
PORTB |= (1 << PB0) | (1 << PB1) | (1 << PB2) | (1 << PB3) | (1 << PB4) | (1 << PB5); /* Enable pull-ups */
/* Button inputs: PC0-PC5 */
DDRC &= ~((1 << PC0) | (1 << PC1) | (1 << PC2) | (1 << PC3) | (1 << PC4) | (1 << PC5));
PORTC |= (1 << PC0) | (1 << PC1) | (1 << PC2) | (1 << PC3) | (1 << PC4) | (1 << PC5); /* Enable pull-ups */
#if defined(__AVR_ATmega8__)
/* ---------- ATmega8 : Timer0 overflow ---------- */
/* F_CPU = 8 MHz
* Prescaler = 64
* Overflow period ≈ 2.048 ms
* idleTicks > 12 gives ~24.6 ms timeout
*/
TCCR0 = (1 << CS01) | (1 << CS00); /* clk/64 */
TCNT0 = 0; /* initialize counter */
TIMSK |= (1 << TOIE0); /* enable overflow interrupt */
#elif defined(__AVR_ATmega88__) || defined(__AVR_ATmega88A__) || defined(__AVR_ATmega88PA__)
/* ---------- ATmega88 / ATmega88A / ATmega88PA / ATmega88PB ---------- */
/* F_CPU = 8 MHz
* Prescaler = 64
* OCR0A = 124 → 1 ms
*/
TCCR0A = (1 << WGM01); /* CTC */
TCCR0B = (1 << CS01) | (1 << CS00); /* clk/64 */
TCNT0 = 0; /* initialize counter */
OCR0A = 124;
TIMSK0 = (1 << OCIE0A);
#endif
sei();
while (1) {
sega_poll_th();
sega_output();
}
}
