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;
+			if(OCR2A != _timer_out)
 				OCR2A = _timer_out;
+
 			break;
 
 		case CH_4:
 			_timer_out				= pwm % 512;
 			_timer_ovf_b			= pwm / 512;
-			_timer_out >>= 1;
+			_timer_out >>= 1;						// divides by 2
+			//OCR2B = _timer_out;
+			if(OCR2B != _timer_out)
 				OCR2B = _timer_out;
+
 			break;
 	}
 }