Fixed issue with not bitshifting the clock prescaler bitmap

src/timer/timer.c

@@ -13,24 +13,72 @@
 #endif
 
 #include "timer.h"
-#include "avr/io.h"
+#include <avr/io.h>
+#include <avr/interrupt.h>
 
-void Timer_SelectClock(void)
+#define FCLK_PER 3333333UL
+#define DIV8 0x3
+#define PERIOD_VALUE 40 
+
+//These are expiremential found values that account for overhead
+//for smaller durations.
+#define OVERHEAD_ONE 226
+#define OVERHEAD_TWO 151
+#define OVERHEAD_THREE 75
+
+
+static uint16_t overflow_count = 0;
+
+
+uint16_t Timer_GetOverflowCount(void)
 {
-    //set the timer to divde the clock by 256
-    //Check datasheet page: 189 
-    TCA0.SINGLE.CTRLA |= 0x6;
-    
+    return overflow_count;
 }
 
-void Timer_Enable(void)
+void Timer_Start(void)
 {
-    TCA0.SINGLE.CTRLA |= (1<<0);
-}
+    //clear the overflow event count
+    overflow_count = 0;
 
-void Timer_Period(void)
-{
-    TCA0.SINGLE.PER = 10000;
+    sei();
+
+    //Enable the overflow Interrupt.
+    TCA0.SINGLE.INTCTRL = TCA_SINGLE_OVF_bm;
+
+    //set Normal mode.
+    TCA0.SINGLE.CTRLB = TCA_SINGLE_WGMODE_NORMAL_gc;
+
+    //Disable event counting.
+    TCA0.SINGLE.EVCTRL &= ~(TCA_SINGLE_CNTEI_bm);
+
+    //Set the Period Value
+    TCA0.SINGLE.PER = PERIOD_VALUE;
+
+    //set the Timer to divide FCLK_PER by 8.
+    TCA0.SINGLE.CTRLA |= (DIV8<<1);
+    
+    //Enable the Timer
+    TCA0.SINGLE.CTRLA |= TCA_SINGLE_ENABLE_bm;
 }
 
 
+void Timer_Disable(void)
+{
+    cli();
+    TCA0.SINGLE.CTRLA &= ~(1<<0);
+    TCA0.SINGLE.CTRLESET |= ((0x3)<<2);
+}
+
+//Triggered on the overflow of the timer A's counter.
+ISR(TCA0_OVF_vect)
+{
+    cli();
+
+    //Increment the Overflow counter.
+    overflow_count += 1;
+
+    // The interrupt flag has to be cleared manually
+    TCA0.SINGLE.INTFLAGS = TCA_SINGLE_OVF_bm;
+
+    sei();
+}

src/timer/timer.h

@@ -10,6 +10,7 @@
 #ifndef TIMER
 #define TIMER
 
+#include "stdbool.h"
 #include "inttypes.h"
 
 /**
@@ -17,11 +18,11 @@
  * @param a The first argument
  */
 
-/**
- * The timer select clock function sets the divider to 256 assuming a
- * default clock diver of 6 is applied to the 20MHz crystal. This gives a
- * 13020.8333 Hz or approximatly 13.02Khz tick rate.
- */
-void Timer_SelectClock(void);
+
+void Timer_Start(void);
+
+void Timer_Disable(void);
+
+uint16_t Timer_GetOverflowCount(void);
 
 #endif // TIMER