Order #4165 - Matek F405-Wte Elrs Wing Flight Controller - Flight Controller failing to parse GPS data internal or external

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1

Order Number: 4165
Product Name: Matek F405-Wte Elrs Wing Flight Controller
Brand: Matek Systems
Over the past 3–4 weeks I have attempted to integrate a GPS module with my flight controller (FC) for a fixed wing UAV project. Despite extensive testing, configuration changes, and hardware verification, the FC has consistently failed to parse GPS data and has also refused to calibrate its internal compass. Multiple independent tests confirm the GPS modules are functional, the wiring is correct, and the UART port itself is operational. These findings strongly suggest the FC is defective or mis manufactured.
Background
• FC bought to go in a Sub 250 g autonomous fixed wing aircraft with GPS navigation and telemetry.
• Hardware used:
o Flight Controller (supplied unit, advertised as supporting GPS on Serial 3 / TX5 RX5).
o Multiple GPS modules (M10 12, M8N, others).
o 433 MHz telemetry module (used to verify UART functionality).
• Software tools:
o Mission Planner (ArduPilot).
o u center (Ublox GPS configuration).

Steps Taken to Troubleshoot
A. GPS Module Verification
• Connected GPS modules to PC via USB TTL.
• Used u center to confirm satellites, baud rate (38400), and UBX protocol output.
• Verified modules powered correctly (LEDs active, ~5 V supply).
• Conclusion: GPS modules are functional.
B. FC UART Testing
• Wired GPS to FC Serial 3 (TX5 RX5) as per datasheet.
• Configured parameters:
o SERIAL3_PROTOCOL = 5 (GPS).
o SERIAL3_BAUD = 38.
o GPS_TYPE = 1 (Ublox).
• Observed Mission Planner messages: “EKF waiting for GPS data” with no “GPS: 0.”
• Performed loopback test (TX→RX short) → confirmed UART echoes correctly.
• Connected telemetry module to TX5 RX5 → telemetry works, proving port hardware is functional.
• Conclusion: UART hardware is good, but GPS data not parsed.
C. Compass Calibration
• Attempted internal compass calibration in Mission Planner.
• Calibration process fails to start or complete.
• Parameters checked (COMPASS_USE = 1).
• Conclusion: Internal compass not responding, likely hardware fault.
D. Alternative Configurations
• Tried GPS on Serial 5.
• Tried different baud rates (57600, 115200).
• Enabled NMEA output alongside UBX in GPS.
• No change — FC still fails to parse GPS data.

  1. Evidence of Troubleshooting
    • Multiple GPS modules tested and confirmed working independently.
    • UART port proven functional with telemetry module and loopback test.
    • Correct wiring (TX↔RX, GND common, VCC ~4.8 V).
    • Correct parameters applied and saved in Mission Planner.
    • Internal compass consistently fails calibration.
    • Weeks of systematic testing eliminate user error as the cause.
  1. Conclusion
    The FC has demonstrated repeated failures across two independent subsystems:
    • GPS data parsing (despite verified GPS modules and working UART).
    • Internal compass calibration (despite correct configuration).
    Given the extensive troubleshooting and evidence provided, I conclude the FC is defective. I respectfully request a replacement unit or confirmation of a known issue with this batch.

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2

Hi there,

Thank you so much for your incredibly detailed report on the Matek F405-WTE ELRS Wing Flight Controller from Order #4165. We really appreciate the time you’ve invested in troubleshooting this—it’s clear you’ve covered all the bases, and that makes our job much easier.

After digging into the specs and your setup, I’ve got some good news and a few suggestions. First off, the internal compass issue isn’t a fault: this flight controller doesn’t have a built-in compass (magnetometer). It only has an IMU for gyro and accel, plus a barometer. So the calibration failure is expected behavior. For compass functionality, you’ll need an external module connected via I2C.

On the GPS side, your wiring and tests sound spot-on, and since the UART works with telemetry, it’s likely a config tweak rather than a defect. The board supports GPS on Serial 3 (TX5/RX5), but UART5 doesn’t have DMA, which can cause parsing hiccups with Ublox modules. Here’s what I’d recommend trying next:

  • Move the GPS to TX1/RX1 (Serial1): This port has better DMA support for reliable data flow.
  • Update parameters in Mission Planner:
    SERIAL1_PROTOCOL = 5 (GPS)
    SERIAL1_BAUDRATE = 38 (38400)
    GPS_TYPE = 1 (Ublox)
    GPS_AUTO_CONFIG = 1 (auto-detects baud/protocol)
    COMPASS_USE = 0 (disable internal compass warnings)
  • Power sequence test: Power the FC with battery first (no USB), wait 30 seconds, then connect USB and check Mission Planner for ‘GPS 1: detected’ messages.

If these don’t get GPS parsing, it could point to a hardware quirk. Your order is well within our 30-day return window and the manufacturer’s typical 1-year warranty for defects, so we’re covered there.

Shall we try these steps, or would you like me to reach out to Matek Systems right away for their take on the GPS issue? Just let me know how you’d like to proceed—we’re here to get this sorted for your fixed-wing project.

Best regards,
Your Unmanned Tech UK Team