fixed an overflow issue in AP_RC

git-svn-id: https://arducopter.googlecode.com/svn/trunk@2074 f9c3cf11-9bcb-44bc-f272-b75c42450872

libraries/AP_RC/AP_RC.cpp

@@ -36,10 +36,10 @@ volatile int16_t timer4diff     = 1500 * 2;
 #define CH_4 3
 
 volatile int8_t		_rc_ch_read;
-volatile uint8_t	_timer_out;
+volatile uint16_t	_timer_out;
-volatile uint8_t	_timer_ovf_a;
+volatile uint16_t	_timer_ovf_a;
-volatile uint8_t	_timer_ovf_b;
+volatile uint16_t	_timer_ovf_b;
-volatile uint8_t	_timer_ovf;
+volatile uint16_t	_timer_ovf;
 
 
 AP_RC::AP_RC()
@@ -117,27 +117,33 @@ AP_RC::output_ch_pwm(uint8_t ch, uint16_t pwm)
 {
 	switch(ch){
 		case CH_1:
-			pwm <<= 1;
+			pwm <<= 1;								// multiplies by 2
 			OCR1A = pwm;
 			break;
 
 		case CH_2:
 			pwm <<= 1;
-			OCR1B = pwm;
+			OCR1B = pwm;							// multiplies by 2
 			break;
 
 		case CH_3:
 			_timer_out				= pwm % 512;
 			_timer_ovf_a			= pwm / 512;
-			_timer_out >>= 1;
+			_timer_out >>= 1;						// divides by 2
-			OCR2A = _timer_out;
+			//OCR2A = _timer_out;
+			if(OCR2A != _timer_out)
+				OCR2A = _timer_out;
+
 			break;
 
 		case CH_4:
 			_timer_out				= pwm % 512;
-			_timer_ovf_b		= pwm / 512;
+			_timer_ovf_b			= pwm / 512;
-			_timer_out >>= 1;
+			_timer_out >>= 1;						// divides by 2
-			OCR2B = _timer_out;
+			//OCR2B = _timer_out;
+			if(OCR2B != _timer_out)
+				OCR2B = _timer_out;
+
 			break;
 	}
 }
@@ -211,10 +217,10 @@ ISR(PCINT0_vect)
 ISR(TIMER1_CAPT_vect) // Timer/Counter1 Capture Event
 {
 	//This is a timer 1 interrupts, executed every 20us
-	PORTB |= B00000001; //Putting the pin high!
+	PORTB 		|= B00000001; 	//Putting the pin high!
-	PORTC |= B00010000; //Putting the pin high!     
+	PORTC 		|= B00010000; 	//Putting the pin high!
-	TCNT2 = 0; //restarting the counter of timer 2
+	TCNT2 		= 0; 			//restarting the counter of timer 2
-	_timer_ovf = 0;
+	_timer_ovf 	= 0;
 }
 
 ISR(TIMER2_OVF_vect)