1 files changed, 20 insertions, 0 deletions
diff --git a/avr.cpp b/avr.cpp
index fca50fb..cd528ba 100644
--- a/avr.cpp
+++ b/avr.cpp
@@ -1,5 +1,6 @@
 #include "avr.h"
 #include "adc.h"
+#include "global.h"
 #include "util.h"
 
 #include <stdint.h>
@@ -21,3 +22,22 @@ void waitForButton(int i) {
   while(getButton() != CLAMP(0, i, 5));
   while(getButton() != 0);
 }
+
+void beep(unsigned long freq) {
+	const int prescalers[7] = {1, 8, 32, 64, 128, 256, 1024};
+	
+	for(int i = 0; i < 7; i++) {
+		if(F_CPU/freq/2/prescalers[i] <= 256) {
+			TCCR2 = (TCCR2&~0x07)|(i+1);
+			OCR2 = F_CPU/freq/2/prescalers[i] - 1;
+			
+			return;
+		}
+	}
+	
+	beepOff();
+}
+
+void beepOff() {
+	TCCR2 &= ~0x07;
+}