106 lines
1.7 KiB
C
106 lines
1.7 KiB
C
#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <util/delay.h>
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#include <tabby/printer.h>
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#include <tabby/avr/uart.h>
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#define TIMER0_INTERVAL 1953
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static volatile uint8_t bits = 0;
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static volatile uint8_t value_in = 0x00; /* Data coming in from Game Boy */
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static volatile uint8_t value_out = 0x00; /* Data going out to Game Boy */
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static volatile tabby_printer_packet header = {
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.type = 0,
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.compression = 0,
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.size = 0
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};
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static volatile uint16_t i = 0,
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b = 0;
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/*
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* Internal clock source interrupt vector
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*/
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ISR(TIMER0_COMPB_vect) {
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value_in >>= 1;
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PORTB |= (1 << PORTB5);
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if (PORTB & (1 << PORTB4)) {
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value_in |= 0x80;
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}
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if (value_out & 0x80) {
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PORTB |= (1 << PORTB3);
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} else {
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PORTB &= ~(1 << PORTB3);
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}
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value_out <<= 1;
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if (--bits == 0) {
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bits = 8;
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}
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/*
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* Chill out for 60µsec, then ride out the rest of the time until the next
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* interrupt with a high as fuck SCK
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*/
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_delay_us(60);
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PORTB &= ~(1 << PORTB5);
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}
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static void clock_setup() {
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/*
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* Configure MISO as output
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*/
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DDRB |= (1 << DDB4);
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/*
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* Configure MOSI as input
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*/
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DDRB &= ~(1 << DDB3);
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/*
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* Configure SCK pin as output
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*/
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DDRB |= (1 << DDB5);
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/*
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* Enable timer interrupt vector
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*/
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TIMSK0 = (1 << TOIE1);
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/*
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* Reset timer counter to zero
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*/
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TCNT1 = 0;
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/*
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* Set timer interval
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*/
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OCR1A = TIMER0_INTERVAL;
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/*
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* Set timer clock divider to 1/1
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*/
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TCCR1B = (1 << CS10);
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}
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int main() {
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uart_init();
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clock_setup();
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sei();
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while (1) {
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uint8_t c = uart_getchar(NULL);
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}
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return 0;
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}
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