Added Piezo Support, code from Oliver.

ArduCopter/config.h

@@ -182,7 +182,18 @@
 # define CURR_AMPS_OFFSET		0.0
 #endif
 #ifndef HIGH_DISCHARGE
-# define HIGH_DISCHARGE		1760
+# define HIGH_DISCHARGE			1760
+#endif
+
+
+#ifndef PIEZO
+# define PIEZO				ENABLED				//Enables Piezo Code and beeps once on Startup to verify operation
+#endif
+#ifndef PIEZO_LOW_VOLTAGE
+# define PIEZO_LOW_VOLTAGE	ENABLED				//Enables Tone on reaching low battery or current alert
+#endif
+#ifndef PIEZO_ARMING
+# define PIEZO_ARMING		ENABLED				//Two tones on ARM, 1 Tone on disarm
 #endif
 
 

ArduCopter/events.pde

@@ -95,3 +95,24 @@ static void relay_toggle()
 	PORTL ^= B00000100;
 }
 
+#if PIEZO == ENABLED
+void piezo_on()
+{
+	digitalWrite(PIEZO_PIN,HIGH);
+	//PORTF |= B00100000;
+}
+
+void piezo_off()
+{
+	digitalWrite(PIEZO_PIN,LOW);
+	//PORTF &= ~B00100000;
+}
+
+void piezo_beep()
+{
+	// Note: This command should not be used in time sensitive loops
+	piezo_on();
+	delay(100);
+	piezo_off();
+}
+#endif

ArduCopter/motors.pde

@@ -31,6 +31,11 @@ static void arm_motors()
 					motor_armed 	= true;
 					arming_counter 	= ARM_DELAY;
 
+					#if PIEZO_ARMING == 1
+					piezo_beep();
+					piezo_beep();
+					#endif
+
 					// Tune down DCM
 					// -------------------
 					#if HIL_MODE != HIL_MODE_ATTITUDE
@@ -92,6 +97,9 @@ static void arm_motors()
 				arming_counter 	= DISARM_DELAY;
 				compass.save_offsets();
 
+				#if PIEZO_ARMING == 1
+				piezo_beep();
+				#endif
 
 				// Tune down DCM
 				// -------------------

ArduCopter/sensors.pde

@@ -126,11 +126,26 @@ static void read_battery(void)
 	}
 
 	#if BATTERY_EVENT == 1
-	if(battery_voltage < g.low_voltage)
+	//if(battery_voltage < g.low_voltage)
+	//	low_battery_event();
+
+	if((battery_voltage < g.low_voltage) || (g.battery_monitoring == 4 && current_total > g.pack_capacity)){
 		low_battery_event();
 
-	if(g.battery_monitoring == 4 && current_total > g.pack_capacity)
-		low_battery_event();
+		#if PIEZO_LOW_VOLTAGE == 1
+		// Only Activate if a battery is connected to avoid alarm on USB only
+		if (battery_voltage1 > 1){
+			piezo_on();
+		}else{
+			piezo_off();
+		}
+		#endif
+
+	}else{
+		#if PIEZO_LOW_VOLTAGE == 1
+			piezo_off();
+		#endif
+	}
 	#endif
 }
 

ArduCopter/system.pde

@@ -103,6 +103,11 @@ static void init_ardupilot()
 		pinMode(LE_LED, OUTPUT);			// GPS status LED
 	#endif
 
+	#if PIEZO == 1
+		pinMode(PIEZO_PIN,OUTPUT);
+		piezo_beep();
+	#endif
+
 
 	if (!g.format_version.load() ||
 	     g.format_version != Parameters::k_format_version) {