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#include <stdio.h>
#include <avr/pgmspace.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include "delay.h"
#include "morse.h"
/* Definitions for pins */
#define PORTB_PTT (1 << 0)
#define PORTB_SYNCn (1 << 2)
#define PORTB_LED (1 << 4)
/* Specify ID here, zero-indexed (E=0, I=1, ...) */
static const uint8_t renard_id = 4;
static const uint8_t num_renards_cycle = 4;
// colon (:) represents ERROR
static const char letters[] = "EISH:";
static const char unique_letter = letters[renard_id];
static char *morse_string = "M O ";
volatile uint8_t reset_time;
volatile uint8_t systick; /* Timer (100Hz increment) */
volatile uint32_t seconds;
/* 200Hz timer interrupt */
ISR(TIM0_COMPA_vect)
{
systick++;
if (systick == 20) {
systick = 0;
seconds += 1;
}
if (reset_time) {
reset_time = 0;
seconds = 0;
}
}
static int inittimer(void)
{
/* Start 200Hz system timer */
TCCR0B |= (1 << WGM01); // Configure timer for CTC mode
TIMSK |= (1 << OCIE0A); // enable compare match A interrupt
OCR0A = (uint8_t)(F_CPU / 64 / 50); // Set CTC compare value to 50ms
TCCR0B |= ((1 << CS00) | (1 << CS01)); // Start timer at Fcpu/64
// Enable interrupts
sei();
return 0;
}
void dah(void)
{
PORTB = PORTB_PTT | PORTB_LED;
delay_ms(3*DIT_DURATION);
PORTB = 0;
delay_ms(DIT_DURATION);
}
void dit(void)
{
PORTB = PORTB_PTT | PORTB_LED;
delay_ms(DIT_DURATION);
PORTB = 0;
delay_ms(DIT_DURATION);
}
int main(void)
{
systick = 0;
seconds = 0;
reset_time = 0;
/* Enable PTT output on PB0 */
DDRB = PORTB_PTT | PORTB_LED;
/* initialise timer interrupt */
inittimer();
morse_string[4] = unique_letter;
const int permanent = (unique_letter == ':');
// In order to have all foxes transmitting all the time
// before sync
int sync_pending = 1;
delay_ms(12*DIT_DURATION);
morse("HB9HI");
delay_ms(12*DIT_DURATION);
while (1) {
const uint32_t second = seconds % 60uL;
const uint32_t minute = seconds / 60uL;
if ((PINB & PORTB_SYNCn) == 0) {
reset_time = 1;
sync_pending = 0;
morse("Y");
delay_ms(6*DIT_DURATION);
}
else if (permanent || sync_pending) {
morse(morse_string);
delay_ms(6*DIT_DURATION);
}
else if (minute >= 25) { // see README.md
/* renard id 0: start at (k * num_renards_cycle) * 60, end at (k * num_renards_cycle) * 60 + 55 */
const int in_timeslot = (minute % (uint32_t)num_renards_cycle) == renard_id;
if (in_timeslot && second < 55) {
morse(morse_string);
delay_ms(6*DIT_DURATION);
}
else {
delay_ms(DIT_DURATION);
}
}
else {
/* renard id 0: start every 30s, with an additional 2s offset depending on renard_id */
const uint32_t second_offset = second % 30uL;
if (second_offset == 2 * renard_id) {
morse_char(unique_letter);
delay_ms(1000); // avoid retrigger in same second
}
else {
delay_ms(50);
}
}
}
return 0;
}
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