Better base template

main.c

@@ -1,38 +1,56 @@
 #include <avr/interrupt.h>
 #include <avr/io.h>
 #include <avr/sleep.h>
-#include <util/delay.h>
+#include <avr/wdt.h>
 
-#define BLINK_TIME 0.5  // 1 second
+#define LED_PIN PB5  // Define the pin connected to the LED
 
-ISR(TIMER1_OVF_vect) {
-    PORTB ^= _BV(PORTB5);                         // Toggle the LED
-    TCNT1 = 65535 - (F_CPU / 1024 * BLINK_TIME);  // Reset timer value
+ISR(TIMER1_COMPA_vect) {
+    // Static variable to keep track of the number of interrupts
+    static uint16_t counter = 0;
+
+    PORTB ^= _BV(LED_PIN);  // Toggle the LED
+
+    // Modulo magic, see below for explanation
+    if (++counter % 2 == 0) {
+        OCR1A = 15624 / 2;
+    } else {
+        OCR1A = 15624 / 16;
+    }
+
+    // Clear the interrupt flag
+    TIFR1 |= (1 << TOV1);
+}
+
+// We will use Timer1 for the interrupt
+void configure_interrupt() {
+    TCNT1 = 0;   // Initialize the counter value to 0
+    TCCR1A = 0;  // Set the timer to normal mode
+    TCCR1B = 0;  // Set the timer to normal mode
+    OCR1A = 15624 / 16;  // 31250 for a 2s delay, 15624 for a 1s delay
+    TCCR1B |= (1 << WGM12);               // Set the timer to CTC mode
+    TCCR1B |= (1 << CS02) | (1 << CS00);  // Set the prescaler to 1024
+    TIMSK1 |= (1 << OCIE1A);              // Enable overflow interrupt
+    sei();  // Enable global interrupts (cli() to disable)
 }
 
 int main(void) {
-    // Set PORTB5 as output
-    DDRB |= _BV(DDB5);
+    // Configure the LED pin as an output
+    DDRB |= _BV(LED_PIN);
 
-    // Initialize TIMER1 value
-    TCNT1 = 65535 - (F_CPU / 1024 * BLINK_TIME);
+    configure_interrupt();
 
-    // Set the prescaler to 1024
-    TCCR1B |= _BV(CS10) | _BV(CS12);
+    // Set the watchdog timer to 8 seconds
+    wdt_enable(WDTO_8S);
 
-    // Enable TIMER1 overflow interrupt
-    TIMSK1 |= _BV(TOIE1);
-
-    // Enable global interrupts
-    // sei();
-
-    // Enable global interrupts with style
-    __asm__ __volatile__ ("sei");
+    // Set the sleep mode to idle
+    set_sleep_mode(SLEEP_MODE_IDLE);
 
+    // Pat the dog and sleep until the next interrupt
     while (1) {
-        // Keep in mind that the sleep mode depth will affect the wake up time
-        sleep_cpu();  // Deep sleep
-        // set_sleep_mode(SLEEP_MODE_IDLE); // Idle sleep
-        // sleep_mode(); // Sets the CPU to whatever mode was set
+        wdt_reset();
+        sleep_mode();
     }
+
+    return 0;
 }