1 files changed, 45 insertions, 0 deletions
diff --git a/aliznayem/get_millis.c b/aliznayem/get_millis.c
new file mode 100644
index 0000000..c3a7cbd
--- /dev/null
+++ b/aliznayem/get_millis.c
@@ -0,0 +1,45 @@
+// Source: https://gist.github.com/adnbr/2439125#file-counting-millis-c
+
+#include "get_millis.h"
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/atomic.h>
+
+volatile unsigned long timer1_millis;
+
+void millis_init()
+{
+    // CTC mode, Clock/8
+    TCCR1B |= (1 << WGM12) | (1 << CS11);
+    
+    // Load the high byte, then the low byte
+    // into the output compare
+    OCR1AH = (CTC_MATCH_OVERFLOW >> 8);
+    OCR1AL = CTC_MATCH_OVERFLOW;
+    sei();
+    
+    // Enable the compare match interrupt
+    #if defined (__AVR_ATmega328__) || defined (__AVR_ATmega328P__)
+        TIMSK1 |= (1 << OCIE1A);
+    #elif defined (__AVR_ATmega64__)
+        TIMSK |= (1 << OCIE1A);
+    #elif defined (__AVR_ATtiny84A__)
+        TIMSK1 |= (1 << OCIE1A);
+    #endif
+}
+
+unsigned long millis()
+{
+    unsigned long millis_return;
+    // ensure this cannnot be disrupted
+    ATOMIC_BLOCK(ATOMIC_FORCEON)
+    {
+        millis_return = timer1_millis;
+    }
+    return millis_return;
+}
+
+ISR (TIMER1_COMPA_vect)
+{
+    timer1_millis++;
+}