feat(ex01): ex01 is complete

ex01/main.c

@@ -0,0 +1,44 @@
+#include <avr/io.h>
+#include "mystd.h"
+#include "utils.h"
+
+#define D1		  PORTB0
+#define D2		  PORTB1
+#define D3		  PORTB2
+#define D4		  PORTB4
+
+#define PRESCALER 256
+#define TIMER_FREQ (F_CPU / PRESCALER)
+
+
+// at a high level:
+// Set the OC1B (PB2) pin as output
+// set the TIMER1 mode to COMPARE (CTC)
+// say to compare against OC1A
+// set the value to be compated at X count
+// say the presacler for the timer is 512
+//
+// all these information are on page ~140
+void timer1_init(void) {
+	// Set PB2 (OC1B) as output
+	DDRB   |= _BV(PB2);
+
+	// CTC mode (WGM12 = 1)
+	TCCR1B |= _BV(WGM12);
+
+	// Toggle OC1B on compare match (COM1B0 = 1)
+	TCCR1A |= _BV(COM1B0);
+
+	// Set compare values
+	OCR1A	= TIMER_FREQ / 2;
+
+	// Start timer with prescaler 256 (CS12)
+	TCCR1B |= _BV(CS12);
+}
+
+int main(void) {
+	timer1_init();
+	while (1) {
+	}
+}
+