Crate cu_ahrs 

cu-ahrs

cu-ahrs is a Copper task that runs the uf-ahrs Mahony filter on standardized IMU payloads (with optional magnetometer) to output roll, pitch, and yaw in radians.

Axis convention

• Body frame matches the aerospace/NED convention: +X forward, +Y right, +Z down.
• Positive rotations follow the right-hand rule about each axis:
  • Roll: right wing down is positive (rotation about +X).
  • Pitch: nose up is positive (rotation about +Y).
  • Yaw: clockwise when looking down along +Z (turning right) is positive.
• Accelerometer readings are expected to include gravity (a level IMU yields roughly [0, 0, +9.81] m/s²).

The task outputs absolute filter orientation (no startup zero reference).

Bare-metal RP2350 demos

Two RP2350 no-std options mirroring mpu9250-whoami:

• examples/rp2350_ahrs.rs: stand-alone loop (no Copper runtime) printing RPY.
• examples/rp2350_copper.rs + examples/rp_copperconfig.ron: full Copper app wiring resources::RpMpu9250Source -> cu_ahrs::CuAhrs -> tasks::RpySink, with SPI/CS/delay provided by a normal Copper resource bundle and a dummy magnetometer source feeding the optional mag input.

# Host clippy/tests remain on the default host target.
cargo clippy -p cu-ahrs
cargo test -p cu-ahrs

# RP2350 firmware builds (no_std): opt-in config/target.
CARGO_CONFIG=.cargo/config.rp2350.toml cargo run --no-default-features --features rp2350-demo --example rp2350_copper

The RP2350 build uses thumbv8m.main-none-eabihf and memory.x matching the original mpu9250-whoami app. It prints RPY (radians) over RTT/defmt. Wire your MPU9250 to SPI1 pins (SCK=GPIO10, MOSI=GPIO11, MISO=GPIO12, CS=GPIO13) on Pico 2W-class boards and flash with probe-rs.

Modules

sinks

Simple sinks for AHRS outputs.

Structs

AhrsPose

Pose expressed as Euler angles (radians) using the aerospace body frame.

CuAhrs

Copper AHRS task that fuses IMU (and optional magnetometer) payloads into roll/pitch/yaw.

CuAhrsDebugState

Typed debug-state view for AHRS internals.