main.c

@@ -1,56 +1,38 @@
 #include <avr/interrupt.h>
 #include <avr/io.h>
 #include <avr/sleep.h>
-#include <avr/wdt.h>
+#include <util/delay.h>
 
-#define LED_PIN PB5  // Define the pin connected to the LED
+#define BLINK_TIME 0.5  // 1 second
 
-ISR(TIMER1_COMPA_vect) {
+ISR(TIMER1_OVF_vect) {
-    // Static variable to keep track of the number of interrupts
+    PORTB ^= _BV(PORTB5);                         // Toggle the LED
-    static uint16_t counter = 0;
+    TCNT1 = 65535 - (F_CPU / 1024 * BLINK_TIME);  // Reset timer value
-
-    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) {
-    // Configure the LED pin as an output
+    // Set PORTB5 as output
-    DDRB |= _BV(LED_PIN);
+    DDRB |= _BV(DDB5);
 
-    configure_interrupt();
+    // Initialize TIMER1 value
+    TCNT1 = 65535 - (F_CPU / 1024 * BLINK_TIME);
 
-    // Set the watchdog timer to 8 seconds
+    // Set the prescaler to 1024
-    wdt_enable(WDTO_8S);
+    TCCR1B |= _BV(CS10) | _BV(CS12);
 
-    // Set the sleep mode to idle
+    // Enable TIMER1 overflow interrupt
-    set_sleep_mode(SLEEP_MODE_IDLE);
+    TIMSK1 |= _BV(TOIE1);
+
+    // Enable global interrupts
+    // sei();
+
+    // Enable global interrupts with style
+    __asm__ __volatile__ ("sei");
 
-    // Pat the dog and sleep until the next interrupt
     while (1) {
-        wdt_reset();
+        // Keep in mind that the sleep mode depth will affect the wake up time
-        sleep_mode();
+        sleep_cpu();  // Deep sleep
+        // set_sleep_mode(SLEEP_MODE_IDLE); // Idle sleep
+        // sleep_mode(); // Sets the CPU to whatever mode was set
     }
-
-    return 0;
 }

makefile

@@ -9,7 +9,7 @@ MCU = atmega328p
 QEMU_MACHINE_NAME = uno
 
 # Compiler flags
-CFLAGS = -std=c99 -Wall -Wno-array-bounds -mmcu=$(MCU) -DF_CPU=16000000UL -Os -g
+CFLAGS = -std=c2x -Wall -Wno-array-bounds -mmcu=$(MCU) -DF_CPU=16000000UL -O3
 
 # Source files
 SRCS = main.c
@@ -30,6 +30,7 @@ all: $(TARGET).hex
 # Link object files
 $(TARGET).elf: $(OBJS)
 	$(CC) $(CFLAGS) $(OBJS) -o $(TARGET).elf
+	avr-strip $(TARGET).elf
 
 # Convert ELF to HEX
 $(TARGET).hex: $(TARGET).elf