diff --git a/src/lib/ecl/attitude_fw/ecl_roll_controller.cpp b/src/lib/ecl/attitude_fw/ecl_roll_controller.cpp
index 2f8129e829..b28ecdabee 100644
--- a/src/lib/ecl/attitude_fw/ecl_roll_controller.cpp
+++ b/src/lib/ecl/attitude_fw/ecl_roll_controller.cpp
@@ -37,10 +37,12 @@
  *
  */
 
+#include "../ecl.h"
 #include "ecl_roll_controller.h"
 
 ECL_RollController::ECL_RollController() :
 	_last_run(0),
+	_tc(0.1f),
 	_last_output(0.0f),
 	_integrator(0.0f),
 	_rate_error(0.0f),
@@ -52,6 +54,15 @@ ECL_RollController::ECL_RollController() :
 float ECL_RollController::control(float roll_setpoint, float roll, float roll_rate,
 				  float scaler, bool lock_integrator, float airspeed_min, float airspeed_max, float aspeed)
 {
+	/* get the usual dt estimate */
+	uint64_t dt_micros = ecl_elapsed_time(&_last_run);
+	_last_run = ecl_absolute_time();
+
+	float dt = (dt_micros > 500000) ? 0.0f : dt_micros / 1000000;
+
+
+
+
 	return 0.0f;
 }
 
diff --git a/src/lib/ecl/attitude_fw/ecl_roll_controller.h b/src/lib/ecl/attitude_fw/ecl_roll_controller.h
index d2b7961316..bba9ae1634 100644
--- a/src/lib/ecl/attitude_fw/ecl_roll_controller.h
+++ b/src/lib/ecl/attitude_fw/ecl_roll_controller.h
@@ -54,7 +54,9 @@ public:
 	void reset_integrator();
 
 	void set_time_constant(float time_constant) {
-		_tc = time_constant;
+		if (time_constant > 0.1f && time_constant < 3.0f) {
+			_tc = time_constant;
+		}
 	}
 	void set_k_p(float k_p) {
 		_k_p = k_p;
diff --git a/src/lib/ecl/ecl.h b/src/lib/ecl/ecl.h
new file mode 100644
index 0000000000..2bd76ce97a
--- /dev/null
+++ b/src/lib/ecl/ecl.h
@@ -0,0 +1,43 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 Estimation and Control Library (ECL). All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name APL nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file ecl.h
+ * Adapter / shim layer for system calls needed by ECL
+ *
+ */
+
+#include <drivers/drv_hrt.h>
+
+#define ecl_absolute_time hrt_absolute_time
+#define ecl_elapsed_time hrt_elapsed_time
\ No newline at end of file