Betaflight 4.5 GPS Rescue Setup Guide

Introduction

This tutorial provides a comprehensive guide to setting up and testing the GPS Rescue feature in Betaflight 4.5 for your quadcopter. With improved GPS functionality, this feature helps ensure that your drone can return safely in the event of a signal loss, enhancing your flying experience and safety.

Chapter 1: GPS Wiring

To properly configure GPS Rescue, begin by connecting the GPS module to your flight controller.

• Connect GPS to Flight Controller
  • Identify the TX and RX wires on the GPS.
  • Connect the TX wire from the GPS to the RX pad on the flight controller and vice versa.
  • If your GPS has a built-in compass, connect the SDA wire to the SDA pad on the flight controller.
  • Power the GPS using a pad that gets power when the USB is connected (preferably a 5V pad).

Tip: If your GPS doesn't power up with USB, it may take longer to acquire satellite lock.

Chapter 2: Get the FC to Talk to the GPS

Once wired, configure the flight controller to recognize the GPS.

• Open the Ports Tab in Betaflight Configurator

  • Set the GPS for the UART number where you connected it.
  • Leave the other settings at default, particularly "Serial RX" to "Auto."

• Configure GPS Settings

  • Go to the GPS tab and select U-Blox for your GPS type.
  • Set both baud rate and auto configuration to “Auto.”
  • Confirm the GPS icon changes to yellow (indicating GPS lock) or red (indicating GPS communication).

Common Pitfall: If the GPS does not respond, manually set the baud rate between 9600 and 115200, starting with 57600 as a recommended option.

Chapter 3: Manual Baud, Galileo, and Ground Assistance

Enhancing GPS performance can be achieved through additional settings.

• Set Baud Rate Manually if Needed

  • If auto settings fail, manually set the baud rate to 115200 or 57600.

• Enable Galileo and Ground Assistance

  • Enable the Galileo option in the GPS settings for improved positioning.
  • Activate Ground Assistance to further enhance accuracy.

• Set Home Point Once

  • Decide whether you want the home point to be set only once when armed. This ensures the home point remains constant until the quad is powered off.

Chapter 4: Test Auto Level

Ensure your quadcopter is ready for GPS Rescue by checking the auto-level feature.

• Calibrate Accelerometer

  • Place the quadcopter flat on a level surface and calibrate it in the Setup tab.

• Test Hover

  • Arm the quadcopter (ensure GPS lock) and switch to angle mode.
  • Observe the hover throttle position, which should be stable (e.g., around 23%).

Chapter 5: Set Stage 1 Failsafe and GPS Hover Throttle

Configure failsafe settings to ensure safe behavior during signal loss.

• Set Stage 1 Failsafe Throttle

  • Adjust the throttle value to your hover throttle position to allow the quad to climb slightly during a failsafe.

• Set GPS Hover Throttle

  • Set this value slightly above your hover throttle (e.g., if hover is 23%, set GPS hover to 27%).

Chapter 6: Pre-flight Checks of GPS Rescue

Before your flight, ensure everything is correctly configured.

• Check Satellites

  • Confirm that the GPS has a good number of satellites locked (ideally 7 or more).

• Test Direction Home

  • Ensure that the direction home arrow points toward your home location.

Chapter 7: First GPS Rescue Test Flight

Conduct initial tests for GPS Rescue functionality.

• Perform the Test
  • Safely position your quad where it can land without damage.
  • Activate GPS Rescue and observe the behavior. Ensure it climbs and heads home correctly.

Chapter 8: Set Up and Test Failsafe Behavior

Simulate failsafe conditions to ensure everything functions correctly.

• Configure Failsafe Mode

  • In the Modes tab, add a failsafe mode using the same switch as GPS Rescue.
  • Set the failsafe behavior to initiate a landing and adjust the throttle to slowly descend.

• Test Failsafe Action

  • Trigger the failsafe and observe the quad's response.

Chapter 9: Set Up and Test GPS Rescue Failsafe

Finalize the GPS Rescue settings for reliable operation during failsafe conditions.

• Configure GPS Rescue as Failsafe Behavior
  • In the failsafe tab, set the behavior to GPS Rescue and select an appropriate altitude for the return home.

Chapter 10: Enable HDOP to Better Know GPS Health

For better monitoring of GPS accuracy, enable HDOP.

• Set Up HDOP in OSD
  • Open the CLI tab and enter:

    set osd_gps_hdop_show = on
    save
    

  • Monitor HDOP value to ensure GPS accuracy (aim for a value below 1.0).

Chapter 11: A Few Gotchas You Should Not Forget

Keep in mind some important reminders for successful operation.

• Always ensure you have a good number of satellites and low HDOP before flying.
• Regularly test GPS Rescue functionality to ensure reliability.
• If you fly in windy conditions, be aware of settings that may need adjustments.

Conclusion

By following this guide, you will have set up and tested the GPS Rescue feature in Betaflight 4.5. Make sure to perform regular pre-flight checks and system tests to maintain reliability. Happy flying, and may your quadcopter always return home safely!