Fix missing magnetometer support on NEXUSX target

[sensei-hacker]

User description

Summary

Fixes "Invalid name" CLI error when users attempt to configure magnetometer settings on NEXUSX target.

Problem

The NEXUSX target was missing USE_MAG definition, causing all magnetometer-related CLI settings to be excluded from the settings table. Users received "Invalid name" errors when trying to use:

• set align_mag_roll=<value>
• set align_mag_pitch=<value>
• set align_mag_yaw=<value>
• Other compass settings (mag_hardware, mag_declination, etc.)

Root Cause

The PG_COMPASS_CONFIG parameter group in settings.yaml has condition: USE_MAG (line 558), which excludes all magnetometer settings when USE_MAG is not defined for the target.

Solution

Added magnetometer support to NEXUSX target:

• Added #define USE_MAG to target.h
• Configured MAG_I2C_BUS to use I2C3 (same bus as barometer)

Hardware Compatibility

NEXUSX board has I2C3 available for external magnetometer:

• I2C3 SCL: PA8
• I2C3 SDA: PC9
• Barometer already on I2C3 (SPL06)
• Compatible with standard I2C magnetometers (HMC5883L, QMC5883, IST8310, LIS3MDL, etc.)

Testing

✅ Built NEXUSX target successfully
✅ Verified settings present in binary via strings command
✅ All compass settings now available:

• align_mag_roll, align_mag_pitch, align_mag_yaw (-1800 to 3600 decidegrees)
• mag_hardware (AUTO, HMC5883, QMC5883, IST8310, etc.)
• mag_declination (-18000 to 18000)
• magzero_x/y/z, maggain_x/y/z
• mag_calibration_time (20-120 seconds)

Impact

• Risk: Low - Only enables missing functionality, no behavior changes
• Flash: Minimal increase (<1KB)
• Default: No change (mag hardware defaults to AUTO, disabled if not detected)
• Backward compatibility: Existing configurations unaffected

Files Changed

• src/main/target/NEXUSX/target.h - Added USE_MAG and MAG_I2C_BUS definitions

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PR Type

Bug fix

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Description

• Enables missing magnetometer support on NEXUSX target

• Adds USE_MAG definition and configures MAG_I2C_BUS to I2C3

• Resolves "Invalid name" CLI errors for compass settings

• Allows external magnetometer configuration via I2C3 bus

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Diagram Walkthrough

flowchart LR
  A["NEXUSX Target"] -->|Missing USE_MAG| B["CLI Errors"]
  B -->|Invalid name| C["Compass Settings Unavailable"]
  A -->|Add USE_MAG| D["Magnetometer Enabled"]
  D -->|Configure MAG_I2C_BUS| E["I2C3 Bus"]
  E -->|Shared with| F["Barometer SPL06"]
  D -->|Enable| G["Compass Settings Available"]

Loading

File Walkthrough

Relevant files

Bug fix

target.h Enable magnetometer on I2C3 bus                                                    src/main/target/NEXUSX/target.h Added #define USE_MAG to enable magnetometer support Added #define MAG_I2C_BUS BUS_I2C3 to configure magnetometer I2C bus Magnetometer shares I2C3 bus with existing barometer (SPL06) Enables all compass-related CLI settings (align_mag_roll/pitch/yaw, mag_hardware, mag_declination, etc.) +3/-0

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[qodo-code-review]

PR Compliance Guide 🔍

All compliance sections have been disabled in the configurations.

[sensei-hacker]

Something to be aware of @functionpointer

[qodo-code-review]

Suggestion: Add a definition for the specific magnetometer hardware driver (e.g., USE_MAG_QMC5883L) to ensure the device is properly initialized, as simply defining USE_MAG is insufficient. [possible issue, importance: 9]

Suggested change

	#define USE_MAG
	#define MAG_I2C_BUS BUS_I2C3
	#define USE_MAG
	#define MAG_I2C_BUS BUS_I2C3
	#define USE_MAG_QMC5883L // Or other magnetometer type used on this board

[qodo-code-review]

Suggestion: Add an explicit note or guard to document/validate the shared I2C3 usage between barometer and magnetometer to prevent accidental divergence and bus conflicts across modules and docs. [Learned best practice, importance: 6]

New proposed code:

 #define USE_BARO
-#define BARO_I2C_BUS            BUS_I2C3
+#define BARO_I2C_BUS            BUS_I2C3     // Shares I2C3 with magnetometer
 #define USE_BARO_SPL06
 
 #define USE_MAG
-#define MAG_I2C_BUS             BUS_I2C3
+#define MAG_I2C_BUS             BUS_I2C3     // Shares I2C3 with barometer (SPL06)

[functionpointer]

Why not I2C2 instead, using DEFAULT_I2C?
That one is more easily accessible on Port C

[functionpointer]

Now that I am properly awake, I can tell you that I2C3 is not physically accessible at all. See the Readme.md.

The only possible interface besides I2C2 is I2C1, which may be mapped on AUX and SBUS pins. However, they are already used by UART1 and two Servo/Motor outputs and the target is currently not set up to use I2C1 at all.

So use I2C2 like this

#define USE_MAG
#define MAG_I2C_BUS             DEFAULT_I2C
#define USE_MAG_ALL