PRO/GPS Firmware Update v4.8

Please read through these Release Notes carefully.

New Features

  1.  Arming Notification.  As an added safety feature the HoverflyPRO now beeps once armed until throttle is increased past 7%.  Once the craft is returned to the ground and the throttle is reduced below 7%, the beeping continues until the craft is dis-armed.
  2. Rate of climb Altitude Slew.  Once Altitude Hold (AH) is engaged in flight the throttle stick function changes to rate of climb.  Near center stick, with a dead-band from 40% to 60%, the rate of climb is 0 and the current altitude is maintained.  From 40% to 0%, the craft descends at a variable rate proportional to the throttle stick up to -10ft/sec at 0%.  From 60% to 100% the craft ascends at a variable rate proportional to the throttle stick up to +10ft/sec at 100%.  Returning the stick to the center dead-band causes the craft to maintain current altitude.
  3. Carefree.  This is not really a new feature since it has been in previous versions of the firmware.  However, many users were not aware that it was available.  You must select it in the PRO Info tab of the Setup Client.  Once the craft is armed, the elevator stick will always move your craft forward pushing up on the stick and backward pulling down on the stick.  Right and Left are coordinated with the aileron stick.  The craft can be yawed with the rudder stick but the craft will no longer have a front direction.  Remember that the front of the craft creates the new orientation grid when the craft is armed.  Please note that Carefree is only active when Auto-Level (AL) is engaged.

Major Fixes

  1. Position Hold (PH).  The GPS Position Hold feature has been completely re-written and now performs well in still, constant wind, and gusty wind conditions.  The user should expect operation within a 10 foot (3 meter) diameter circle about the PH target location.  In wind, the craft will fall off and return to the target location with the required roll/pitch angle to maintain position.  The position of the craft can be slewed using the aileron/elevator stick.  The craft will enter auto-leveling mode and allow the user to move the craft to a new location.  Once the aileron/elevator stick is returned to center for 1.5 seconds, the craft will maintain the new location using the Position Hold feature.
  2. Return-to-Home (RTH).  The GPS location where the craft was armed is stored as the Home position.  At any time the user can engage the Return-to-Home feature and the craft will automatically return to the Home location.  Be aware that at this time the user must land the craft manually.  This feature has been completely re-written and now performs well in all conditions.

Minor Fixes 

  1. Manual Mode Correction.  A change was inadvertently made in v4.6 to the stability algorithm in Manual Mode.  The change was barely noticeable in v4.6 but tended to add a minute shake at some throttle values.  The change was removed and Manual Mode stability was returned to its previous performance.

Things to Be Aware Of

  1. There is no change to the GPS antenna module.  The HoverflyGPS is compatible with the original Mediatek (small footprint), new Mediatek (larger footprint), DT2523 UBlox Leah-5, GS407 UBlox Leah-5.  There is no need to purchase another GPS antenna module.
  2. External magnetometer.  In some craft, the on-board magnetometer on the HoverflyGPS is subjected to a large amount of magnetic bias.  The result is that as the throttle is raised and lowered the apparent compass bearing of the craft is artificially changed.  This is primarily due to the current flowing in the power harness which in most cases is directly beneath the PRO/GPS stack.  Twisting power wires where possible or re-routing them further away from the PRO/GPS can reduce or eliminate this problem.  However, it is sometimes not possible to do this.  An external magnetometer can be used to easily eliminate the problem.  Please see this technical note for more details.
  3. If the LED on the HoverflyGPS continues to blink purple once it is armed, you may need to replace your GPS antenna module. This will also happen if the SD card is removed from the HoveflyGPS board.
  4. If you are using an external magnetometer watch the LED on the HoverflyGPS when the craft is first powered.  The LED should emit green for a few seconds to indicate the external magnetometer is detected.  The LED will then blink purple and solid red if the external GPS antenna is detected.
  5. You should always wait for the LED on the HoverflyGPS to turn solid green for several seconds before arming the craft if you plan to use the GPS features.  You may arm before the LED turns green but GPS functions will not be available until you land and disarm.
  6. There is no gain adjustment for Altitude Hold.  You can return your switch values to their default settings.  The Altitude Hold feature no longer needs to be tuned.

Update Procedure

  1. Use the Firmware Update tool to update the firmware on both the HoverflyPRO and the HoverflyGPS.
  2. If you are using an external magnetometer make sure that the orientation is aligned with the craft.
  3. Take the craft outside preferably in a field away from large metal objects.  You should also move off of sidewalks or concrete which often contains steel rods.  Determine the direction of Magnetic North in your area.  Please note that this may differ significantly from True North depending upon your location.  You can determine your local declination using this tool: .  Power the transmitter and then the craft.  Move the throttle to max and then to the right while dis-armed.  The HoverflyPRO will beep several times to indicate that you have entered magnetometer calibration mode.  Imagine that the craft is a six-sided cube.  The magnetometer calibration requires that each axis of the cube be pointed directly at North.  Our method is to point the front of the craft towards north.  Pitch the craft and rotate it 360 degrees (end over end) twice.  Now point the front of the craft towards West and roll the craft 360 degrees (side over side) twice.  Another method is to hold the craft in front of you with the front facing North.  Now spin around while holding the craft for two 360 degree rotations.  Now point the front of the craft down and spin around once again twice.
  4. Return to your computer.
  5. Open the Setup Client click on the PRO information tab and connect to the HoverflyPRO.  IGNORE THE FIRMWARE VERSION NUMBER FOR THIS RELEASE.  Verify that the correct geometry is selected.  Verify that the smoothness settings and other modes are selected as you desire.  Confirm that the Acceleration and Temperature calibration check boxes are checked.  If one is missing “Save” and then perform the calibrations using the Calibrations tab.
  6. Select the GPS Info tab and connect to the HoverflyGPS (switch the USB cable from the HoverflyPRO to the HoverflyGPS).  Confirm that the GPS module is connected and that the calibration is checked.  You most likely will not be able to get a GPS fix inside.
  7. Select the General tab and power your transmitter and then your craft.  Verify that all of your controls are working correctly.  Check that all of the feature switches for AH, AL, PH, and RTH are working using the checkboxes in the Setup Client.
  8. GAIN ADJUSTMENT.  Because of the numerous changes in v4.8 you should verify that the Primary Gain is optimized.  Follow the procedure in the HoverflyPRO manual to tune the Primary Gain.  Once you are satisfied set the Auto-level Gain to the same value (on your transmitter.  There is no need to adjust it exactly in the Setup Client).
  9. Perform a test flight.
    1. Get some altitude (maybe 100 feet) and test the Altitude Hold feature. 
    2. Move to a location a safe distance away (maybe 30 feet) land and dis-arm.  Re-arm the craft and activate Position Hold.  You may also want to activate Altitude Hold at the same time.  Observe the position of the craft.  If the craft is circling and you are using an external magnetometer check to make sure that it is aligned with the craft properly.  If it is try turning it clockwise 5 degrees and repeat the Position Hold test.  If the circling gets worse try turning it counter clockwise 5 degrees in the opposite direction.  Repeat until the circling is eliminated.  If you are using the on-board magnetometer then you most likely need to install an external magnetometer.  Another cause of the circling is non-optimal gain.  If you are using a gain that is too low for your craft it can result in poor Position Hold performance.  You should re-adjust your Primary and Auto-level gains.
    3.  Move the craft some distance away and activate Return-to-Home.  The craft should fly back to the Home location at a constant velocity of approximately 10 feet/sec.

Keys to GPS Success

  1. Optimal Primary Gain tuning.  Autolevel gain should be set to the same value on your transmitter.
  2. Accelerometer, Temperature and Magnetometer calibrations should be completed and you should verify that the check box is checked in the Setup Client.
  3. The craft should be well trimmed using Auto-Level.  A procedure is described in the manual.


Next Release

  1. Auto-landing in Return-to-Home.
  2. Adding additional motion data to Altitude Hold and Position Hold features to further increase performance.
  3. Adding automatic Altitude Hold when using Position Hold and Return-to-Home.
  4. Throttle adjustment while in Altitude Hold to maintain altitude during higher speed maneuvering.
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