Add level calibration

flix/cli.ino

@@ -42,6 +42,7 @@ const char* motd =
 "log [dump] - print log header [and data]\n"
 "cr - calibrate RC\n"
 "ca - calibrate accel\n"
+"cl - calibrate level\n"
 "mfr, mfl, mrr, mrl - test motor (remove props)\n"
 "sys - show system info\n"
 "reset - reset drone's state\n"

flix/imu.ino

@@ -44,6 +44,13 @@ void readIMU() {
 	gyro = Quaternion::rotateVector(gyro, rotation.inversed());
 }
 
+void calibrateLevel() {
+	print("Place perfectly level [1 sec]\n");
+	pause(1);
+	Quaternion correction = Quaternion::fromBetweenVectors(Quaternion::rotateVector(Vector(0, 0, 1), attitude), Vector(0, 0, 1));
+	imuRotation = Quaternion::rotate(correction, Quaternion::fromEuler(imuRotation)).toEuler();
+	print("✓ Done: %.3f %.3f %.3f\n", degrees(imuRotation.x), degrees(imuRotation.y), degrees(imuRotation.z));
+}
 
 void calibrateGyroOnce() {
 	static Delay landedDelay(2);