Improved sensor startup and error checking

ROMFS/px4fmu_common/init.d/rc.sensors

@@ -24,6 +24,10 @@ then
 	hmc5883 start
 	set BOARD fmuv1
 else
+	if hmc5883 start
+	then
+		echo "Using external mag"
+	fi
 	echo "using L3GD20 and LSM303D"
 	l3gd20 start
 	lsm303d start

src/modules/sensors/sensors.cpp

@@ -953,7 +953,7 @@ Sensors::baro_init()
 
 	if (fd < 0) {
 		warn("%s", BARO_DEVICE_PATH);
-		warnx("No barometer found, ignoring");
+		errx(1, "FATAL: No barometer found");
 	}
 
 	/* set the driver to poll at 150Hz */

src/systemcmds/preflight_check/preflight_check.c

@@ -263,7 +263,7 @@ system_eval:
 		led_toggle(leds, LED_BLUE);
 
 		/* display and sound error */
-		for (int i = 0; i < 150; i++)
+		for (int i = 0; i < 50; i++)
 		{
 			led_toggle(leds, LED_BLUE);
 			led_toggle(leds, LED_AMBER);