Since Stratux firmware version v1.6r1-eu028 the AHRS flight sensor (Attitude Heading Reference System) is no longer recognized, depending on the chips used.
The Problem
After updating to v1.6r1-eu028, many users reported that their AHRS sensor (typically using a GY-91 or similar module) was no longer being detected. The issue is related to the I2C address configuration.
Why Does This Happen?
The GY-91 module contains multiple sensors:
- MPU-9250: 9-axis motion sensor (accelerometer, gyroscope, magnetometer)
- BMP280: Barometric pressure sensor
Different manufacturers use different I2C addresses for these chips. The firmware update changed the expected addresses, causing compatibility issues with some sensor modules.
The Solution
You can fix this issue by installing a patch file through the Stratux web interface:
Step-by-Step Instructions
1. Download the fix file
- Download the I2C address fix .sh file from the Stratux community resources
2. Connect to Stratux
- Power on your Stratux device
- Connect to the Stratux WiFi network
- Open http://192.168.10.1 in your browser
3. Install the patch
- Navigate to Settings → Developer
- Upload the .sh file
- Wait for the script to execute
- Reboot your Stratux
4. Verify the fix
- After reboot, check the Status page
- AHRS should now show as "Connected" or "OK"
- Verify attitude data is being displayed correctly
Alternative Addresses
The common I2C addresses for these sensors are:
| Sensor | Default Address | Alternative Address |
|--------|-----------------|---------------------|
| MPU-9250 | 0x68 | 0x69 |
| BMP280 | 0x76 | 0x77 |
The patch script checks for sensors at both addresses and configures Stratux accordingly.
Preventing Future Issues
- Keep backups of working configurations
- Test AHRS functionality after each firmware update
- Join the Stratux community forums for quick support
Conclusion
This is a common issue that affects many Stratux users after firmware updates. The fix is straightforward and can be applied without re-flashing the SD card. If you continue to have issues, check the Stratux GitHub repository for the latest fixes and updates.
Related Resources
- Buy AHRS Sensors for Stratux - GY-91 MPU-9250 + BMP280 sensor module
- Latest Generation AHRS Sensor ICM-20948 - Upgraded 9-axis AHRS sensor
- How to Add AHRS & Altitude Sensor - Complete installation guide
- AHRS & Synthetic Vision Guide - Learn how AHRS works in Stratux