diff --git a/src/drivers/airspeed/airspeed.cpp b/src/drivers/airspeed/airspeed.cpp
index 5e45cc936c..f73a3ef01e 100644
--- a/src/drivers/airspeed/airspeed.cpp
+++ b/src/drivers/airspeed/airspeed.cpp
@@ -91,7 +91,7 @@ Airspeed::Airspeed(int bus, int address, unsigned conversion_interval) :
 	_comms_errors(perf_alloc(PC_COUNT, "airspeed_comms_errors"))
 {
 	// enable debug() calls
-	_debug_enabled = true;
+	_debug_enabled = false;
 
 	// work_cancel in the dtor will explode if we don't do this...
 	memset(&_work, 0, sizeof(_work));
diff --git a/src/drivers/px4io/px4io.cpp b/src/drivers/px4io/px4io.cpp
index a54bb39646..df847a64da 100644
--- a/src/drivers/px4io/px4io.cpp
+++ b/src/drivers/px4io/px4io.cpp
@@ -451,7 +451,7 @@ private:
 namespace
 {
 
-PX4IO	*g_dev;
+PX4IO	*g_dev = nullptr;
 
 }
 
@@ -505,7 +505,7 @@ PX4IO::PX4IO(device::Device *interface) :
 	/* open MAVLink text channel */
 	_mavlink_fd = ::open(MAVLINK_LOG_DEVICE, 0);
 
-	_debug_enabled = true;
+	_debug_enabled = false;
 	_servorail_status.rssi_v = 0;
 }
 
@@ -580,6 +580,12 @@ PX4IO::init()
 	/* get some parameters */
 	unsigned protocol = io_reg_get(PX4IO_PAGE_CONFIG, PX4IO_P_CONFIG_PROTOCOL_VERSION);
 
+	if (protocol == _io_reg_get_error) {
+		log("failed to communicate with IO");
+		mavlink_log_emergency(_mavlink_fd, "[IO] failed to communicate with IO, abort.");
+		return -1;
+	}
+
 	if (protocol != PX4IO_PROTOCOL_VERSION) {
 		log("protocol/firmware mismatch");
 		mavlink_log_emergency(_mavlink_fd, "[IO] protocol/firmware mismatch, abort.");
@@ -774,8 +780,6 @@ PX4IO::task_main()
 	hrt_abstime poll_last = 0;
 	hrt_abstime orb_check_last = 0;
 
-	log("starting");
-
 	_thread_mavlink_fd = ::open(MAVLINK_LOG_DEVICE, 0);
 
 	/*
@@ -809,8 +813,6 @@ PX4IO::task_main()
 	fds[0].fd = _t_actuator_controls_0;
 	fds[0].events = POLLIN;
 
-	log("ready");
-
 	/* lock against the ioctl handler */
 	lock();
 
@@ -1673,7 +1675,18 @@ PX4IO::mixer_send(const char *buf, unsigned buflen, unsigned retries)
 				total_len++;
 			}
 
-			int ret = io_reg_set(PX4IO_PAGE_MIXERLOAD, 0, (uint16_t *)frame, total_len / 2);
+			int ret;
+
+			for (int i = 0; i < 30; i++) {
+				/* failed, but give it a 2nd shot */
+				ret = io_reg_set(PX4IO_PAGE_MIXERLOAD, 0, (uint16_t *)frame, total_len / 2);
+
+				if (ret) {
+					usleep(333);
+				} else {
+					break;
+				}
+			}
 
 			/* print mixer chunk */
 			if (debuglevel > 5 || ret) {
@@ -1697,7 +1710,18 @@ PX4IO::mixer_send(const char *buf, unsigned buflen, unsigned retries)
 		msg->text[0] = '\n';
 		msg->text[1] = '\0';
 
-		int ret = io_reg_set(PX4IO_PAGE_MIXERLOAD, 0, (uint16_t *)frame, (sizeof(px4io_mixdata) + 2) / 2);
+		int ret;
+
+		for (int i = 0; i < 30; i++) {
+			/* failed, but give it a 2nd shot */
+			ret = io_reg_set(PX4IO_PAGE_MIXERLOAD, 0, (uint16_t *)frame, (sizeof(px4io_mixdata) + 2) / 2);
+
+			if (ret) {
+				usleep(333);
+			} else {
+				break;
+			}
+		}
 
 		if (ret)
 			return ret;
@@ -2699,6 +2723,7 @@ px4io_main(int argc, char *argv[])
 			printf("[px4io] loaded, detaching first\n");
 			/* stop the driver */
 			delete g_dev;
+			g_dev = nullptr;
 		}
 
 		PX4IO_Uploader *up;
@@ -2782,10 +2807,6 @@ px4io_main(int argc, char *argv[])
 				delete interface;
 				errx(1, "driver alloc failed");
 			}
-
-			if (OK != g_dev->init()) {
-				warnx("driver init failed, still trying..");
-			}
 		}
 
 		uint16_t arg = atol(argv[2]);
@@ -2797,6 +2818,7 @@ px4io_main(int argc, char *argv[])
 
 		// tear down the px4io instance
 		delete g_dev;
+		g_dev = nullptr;
 
 		// upload the specified firmware
 		const char *fn[2];
@@ -2855,6 +2877,7 @@ px4io_main(int argc, char *argv[])
 
 		/* stop the driver */
 		delete g_dev;
+		g_dev = nullptr;
 		exit(0);
 	}
 
diff --git a/src/drivers/px4io/px4io_uploader.cpp b/src/drivers/px4io/px4io_uploader.cpp
index d9f991210d..dd8abbac5a 100644
--- a/src/drivers/px4io/px4io_uploader.cpp
+++ b/src/drivers/px4io/px4io_uploader.cpp
@@ -121,8 +121,15 @@ PX4IO_Uploader::upload(const char *filenames[])
 	cfsetspeed(&t, 115200);
 	tcsetattr(_io_fd, TCSANOW, &t);
 
-	/* look for the bootloader */
-	ret = sync();
+	/* look for the bootloader for 150 ms */
+	for (int i = 0; i < 15; i++) {
+		ret = sync();
+		if (ret == OK) {
+			break;
+		} else {
+			usleep(10000);
+		}
+	}
 
 	if (ret != OK) {
 		/* this is immediately fatal */
diff --git a/src/drivers/px4io/uploader.h b/src/drivers/px4io/uploader.h
index 22387a3e23..55f63eef96 100644
--- a/src/drivers/px4io/uploader.h
+++ b/src/drivers/px4io/uploader.h
@@ -91,7 +91,7 @@ private:
 	void			drain();
 	int			send(uint8_t c);
 	int			send(uint8_t *p, unsigned count);
-	int			get_sync(unsigned timeout = 1000);
+	int			get_sync(unsigned timeout = 40);
 	int			sync();
 	int			get_info(int param, uint32_t &val);
 	int			erase();
diff --git a/src/modules/px4iofirmware/mixer.cpp b/src/modules/px4iofirmware/mixer.cpp
index e55ef784a9..2e79f0ac65 100644
--- a/src/modules/px4iofirmware/mixer.cpp
+++ b/src/modules/px4iofirmware/mixer.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2014 PX4 Development Team. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -71,6 +71,7 @@ extern "C" {
 static bool mixer_servos_armed = false;
 static bool should_arm = false;
 static bool should_always_enable_pwm = false;
+static volatile bool in_mixer = false;
 
 /* selected control values and count for mixing */
 enum mixer_source {
@@ -95,6 +96,7 @@ static void mixer_set_failsafe();
 void
 mixer_tick(void)
 {
+
 	/* check that we are receiving fresh data from the FMU */
 	if (hrt_elapsed_time(&system_state.fmu_data_received_time) > FMU_INPUT_DROP_LIMIT_US) {
 
@@ -199,13 +201,17 @@ mixer_tick(void)
 		}
 
 
-	} else if (source != MIX_NONE) {
+	} else if (source != MIX_NONE && (r_status_flags & PX4IO_P_STATUS_FLAGS_MIXER_OK)) {
 
 		float	outputs[PX4IO_SERVO_COUNT];
 		unsigned mixed;
 
 		/* mix */
+
+		/* poor mans mutex */
+		in_mixer = true;
 		mixed = mixer_group.mix(&outputs[0], PX4IO_SERVO_COUNT);
+		in_mixer = false;
 
 		pwm_limit_calc(should_arm, mixed, r_page_servo_disarmed, r_page_servo_control_min, r_page_servo_control_max, outputs, r_page_servos, &pwm_limit);
 
@@ -297,12 +303,17 @@ mixer_callback(uintptr_t handle,
 static char mixer_text[256];		/* large enough for one mixer */
 static unsigned mixer_text_length = 0;
 
-void
+int
 mixer_handle_text(const void *buffer, size_t length)
 {
 	/* do not allow a mixer change while safety off */
 	if ((r_status_flags & PX4IO_P_STATUS_FLAGS_SAFETY_OFF)) {
-		return;
+		return 1;
+	}
+
+	/* abort if we're in the mixer */
+	if (in_mixer) {
+		return 1;
 	}
 
 	px4io_mixdata	*msg = (px4io_mixdata *)buffer;
@@ -310,7 +321,7 @@ mixer_handle_text(const void *buffer, size_t length)
 	isr_debug(2, "mix txt %u", length);
 
 	if (length < sizeof(px4io_mixdata))
-		return;
+		return 0;
 
 	unsigned	text_length = length - sizeof(px4io_mixdata);
 
@@ -328,13 +339,16 @@ mixer_handle_text(const void *buffer, size_t length)
 	case F2I_MIXER_ACTION_APPEND:
 		isr_debug(2, "append %d", length);
 
+		/* disable mixing during the update */
+		r_status_flags &= ~PX4IO_P_STATUS_FLAGS_MIXER_OK;
+
 		/* check for overflow - this would be really fatal */
 		if ((mixer_text_length + text_length + 1) > sizeof(mixer_text)) {
 			r_status_flags &= ~PX4IO_P_STATUS_FLAGS_MIXER_OK;
-			return;
+			return 0;
 		}
 
-		/* append mixer text and nul-terminate */
+		/* append mixer text and nul-terminate, guard against overflow */
 		memcpy(&mixer_text[mixer_text_length], msg->text, text_length);
 		mixer_text_length += text_length;
 		mixer_text[mixer_text_length] = '\0';
@@ -369,6 +383,8 @@ mixer_handle_text(const void *buffer, size_t length)
 
 		break;
 	}
+
+	return 0;
 }
 
 static void
diff --git a/src/modules/px4iofirmware/px4io.c b/src/modules/px4iofirmware/px4io.c
index e2da359394..d4c25911e3 100644
--- a/src/modules/px4iofirmware/px4io.c
+++ b/src/modules/px4iofirmware/px4io.c
@@ -295,10 +295,12 @@ user_start(int argc, char *argv[])
 
                 check_reboot();
 
-		/* check for debug activity */
+		/* check for debug activity (default: none) */
 		show_debug_messages();
 
-		/* post debug state at ~1Hz */
+		/* post debug state at ~1Hz - this is via an auxiliary serial port
+		 * DEFAULTS TO OFF!
+		 */
 		if (hrt_absolute_time() - last_debug_time > (1000 * 1000)) {
 
 			struct mallinfo minfo = mallinfo();
diff --git a/src/modules/px4iofirmware/px4io.h b/src/modules/px4iofirmware/px4io.h
index bffbc0ce2a..393e0560e8 100644
--- a/src/modules/px4iofirmware/px4io.h
+++ b/src/modules/px4iofirmware/px4io.h
@@ -178,7 +178,7 @@ extern pwm_limit_t pwm_limit;
  * Mixer
  */
 extern void	mixer_tick(void);
-extern void	mixer_handle_text(const void *buffer, size_t length);
+extern int	mixer_handle_text(const void *buffer, size_t length);
 
 /**
  * Safety switch/LED.
diff --git a/src/modules/px4iofirmware/registers.c b/src/modules/px4iofirmware/registers.c
index a59dbe89cf..19fc61f78b 100644
--- a/src/modules/px4iofirmware/registers.c
+++ b/src/modules/px4iofirmware/registers.c
@@ -380,7 +380,10 @@ registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num
 
 		/* handle text going to the mixer parser */
 	case PX4IO_PAGE_MIXERLOAD:
-		mixer_handle_text(values, num_values * sizeof(*values));
+		if (!(r_status_flags & PX4IO_P_STATUS_FLAGS_SAFETY_OFF) ||
+				    (r_status_flags & PX4IO_P_STATUS_FLAGS_OUTPUTS_ARMED)) {
+			return mixer_handle_text(values, num_values * sizeof(*values));
+		}
 		break;
 
 	default:
@@ -507,8 +510,7 @@ registers_set_one(uint8_t page, uint8_t offset, uint16_t value)
 
 		case PX4IO_P_SETUP_REBOOT_BL:
 			if ((r_status_flags & PX4IO_P_STATUS_FLAGS_SAFETY_OFF) ||
-			    (r_status_flags & PX4IO_P_STATUS_FLAGS_OVERRIDE) ||
-			    (r_setup_arming & PX4IO_P_SETUP_ARMING_FMU_ARMED)) {
+			    (r_status_flags & PX4IO_P_STATUS_FLAGS_OUTPUTS_ARMED)) {
 				// don't allow reboot while armed
 				break;
 			}
@@ -538,8 +540,7 @@ registers_set_one(uint8_t page, uint8_t offset, uint16_t value)
 		 * do not allow a RC config change while outputs armed
 		 */
 		if ((r_status_flags & PX4IO_P_STATUS_FLAGS_SAFETY_OFF) ||
-			(r_status_flags & PX4IO_P_STATUS_FLAGS_OVERRIDE) ||
-			(r_setup_arming & PX4IO_P_SETUP_ARMING_FMU_ARMED)) {
+			    (r_status_flags & PX4IO_P_STATUS_FLAGS_OUTPUTS_ARMED)) {
 			break;
 		}
 
diff --git a/src/modules/sensors/sensors.cpp b/src/modules/sensors/sensors.cpp
index 5e8c5edbcf..ea864390da 100644
--- a/src/modules/sensors/sensors.cpp
+++ b/src/modules/sensors/sensors.cpp
@@ -795,7 +795,6 @@ Sensors::accel_init()
 
 #endif
 
-		warnx("using system accel");
 		close(fd);
 	}
 }
@@ -835,7 +834,6 @@ Sensors::gyro_init()
 
 #endif
 
-		warnx("using system gyro");
 		close(fd);
 	}
 }
@@ -1505,9 +1503,6 @@ void
 Sensors::task_main()
 {
 
-	/* inform about start */
-	warnx("Initializing..");
-
 	/* start individual sensors */
 	accel_init();
 	gyro_init();