Merge pull request #2961 from jan-r/issue292-fix

Tone: fix for ATmega8

Author: facchinm

hardware/arduino/avr/cores/arduino/Tone.cpp

@@ -30,6 +30,7 @@ Version Modified By Date     Comments
 0006    D Mellis    09/12/29 Replaced objects with functions
 0007    M Sproul    10/08/29 Changed #ifdefs from cpu to register
 0008    S Kanemoto  12/06/22 Fixed for Leonardo by @maris_HY
+0009    J Reucker   15/04/10 Issue #292 Fixed problems with ATmega8 (thanks to Pete62)
 *************************************************/
 
 #include <avr/interrupt.h>
@@ -296,13 +297,13 @@ void tone(uint8_t _pin, unsigned int frequency, unsigned long duration)
 #if defined(TCCR0B)
       if (_timer == 0)
       {
-        TCCR0B = prescalarbits;
+        TCCR0B = (TCCR0B & 0b11111000) | prescalarbits;
       }
       else
 #endif
 #if defined(TCCR2B)
       {
-        TCCR2B = prescalarbits;
+        TCCR2B = (TCCR2B & 0b11111000) | prescalarbits;
       }
 #else
       {
@@ -389,15 +390,15 @@ void tone(uint8_t _pin, unsigned int frequency, unsigned long duration)
         break;
 #endif
 
-#if defined(TIMSK3)
+#if defined(OCR3A) && defined(TIMSK3) && defined(OCIE3A)
       case 3:
         OCR3A = ocr;
         timer3_toggle_count = toggle_count;
         bitWrite(TIMSK3, OCIE3A, 1);
         break;
 #endif
 
-#if defined(TIMSK4)
+#if defined(OCR4A) && defined(TIMSK4) && defined(OCIE4A)
       case 4:
         OCR4A = ocr;
         timer4_toggle_count = toggle_count;
@@ -454,21 +455,21 @@ void disableTimer(uint8_t _timer)
       #endif
       break;
 
-#if defined(TIMSK3)
+#if defined(TIMSK3) && defined(OCIE3A)
     case 3:
-      TIMSK3 = 0;
+      bitWrite(TIMSK3, OCIE3A, 0);
       break;
 #endif
 
-#if defined(TIMSK4)
+#if defined(TIMSK4) && defined(OCIE4A)
     case 4:
-      TIMSK4 = 0;
+      bitWrite(TIMSK4, OCIE4A, 0);
       break;
 #endif
 
-#if defined(TIMSK5)
+#if defined(TIMSK5) && defined(OCIE5A)
     case 5:
-      TIMSK5 = 0;
+      bitWrite(TIMSK5, OCIE5A, 0);
       break;
 #endif
   }