STM32 Boards¶

Veloxity currently has firmware crates for two STM32H7 boards:

Nucleo-H753ZI: boards/nucleo
Pixracer Pro: boards/pixracerpro

Pixracer Pro is the active STM32 hardware-validation target. Nucleo-H753ZI is retained and checked for compilation, but its sensors and hardware behavior need renewed validation.

For the meaning of the repository's check, build, and flash commands, see Build and Tool Commands. For the shared World, BoardIo, and scheduler architecture, see Veloxity Core Architecture.

Board Differences¶

Both crates initialize STM32 peripherals, implement BoardIo, construct a concrete World, and run Embassy tasks that collect sensor and communication data. The important differences are:

Area	Nucleo-H753ZI	Pixracer Pro
Current status	Compiles; renewed hardware validation needed.	Active STM32 hardware-validation target.
Firmware loop	Calls `World::run_once()`.	Uses the realtime scheduler with a fixed `400 Hz` control rate.
IMU	BMI088 at `400 Hz`.	BMI085 at `400 Hz`.
Magnetometer	IIS2MDC.	IST8308.
Air-data and range sensors	DLHRL20G is constructed, but its task is currently disabled.	MS4525 airspeed and LLV3HP range sensor.
MAVLink transport	Telemetry UART.	Telemetry UART by default; USB VCP is an optional build feature.
Outputs	Twelve standard PWM outputs.	Seven standard PWM outputs.

The Pixracer Pro service policy polls service work repeatedly while enough time remains before the next control deadline. This lets MAVLink and slower sensors make progress without moving them into the IMU/control path. The detailed scheduler behavior can be found in the architecture guide.

Source Layout¶

Path	Purpose
`boards/nucleo/src/bin/veloxity.rs`	Nucleo firmware entry point and `World` construction.
`boards/nucleo/src/board.rs`	Nucleo peripheral setup and `BoardIo` implementation.
`boards/pixracerpro/src/bin/veloxity.rs`	Pixracer Pro firmware entry point and `World` construction.
`boards/pixracerpro/src/board.rs`	Pixracer Pro peripheral setup and `BoardIo` implementation.
`boards/pixracerpro/src/pwm.rs`	Pixracer Pro PWM adapter.
`platforms/stm_32/stm32h7x3_common.rs`	Shared STM32H7 clock and interrupt configuration.
`platforms/stm_32/src/peripherals/`	Shared STM32 peripheral drivers and Embassy tasks.

Quick Start¶

Install the Rust target and probe-rs tooling:

rustup target add thumbv7em-none-eabihf
cargo install probe-rs-tools

Check or build the board you intend to use:

cargo xtask check-board nucleo
cargo xtask build-board nucleo

cargo xtask check-board pixracerpro
cargo xtask build-board pixracerpro

check-board type-checks the selected firmware. build-board produces a development-profile firmware binary under target/; it does not connect to or modify a board.

Flashing warning¶

The repository currently configures one runner for every thumbv7em-none-eabihf crate:

runner = "probe-rs run --chip STM32H743IIKx"

That chip selection is intended for Pixracer Pro. The flash-board command does not currently replace it with a board-specific chip, so the nucleo cannot be flashed without a full probe-rs command (to be included here after our team revalidates the nucleo)

List connected probes before flashing:

probe-rs list

For the currently configured Pixracer Pro path:

cargo xtask flash-board pixracerpro

This flashes an optimized release build with UART MAVLink transport and no optional features. The Pixracer Pro diagnostic and USB options are documented in Feature Flags.

Hardware And Peripheral Map¶

The shared STM32 platform contains more drivers than either board currently uses. This table distinguishes active board tasks from code that is only available in the platform:

Driver or path	Nucleo-H753ZI	Pixracer Pro
BMI08x IMU	Active as BMI088.	Active as BMI085.
DPS310 barometer	Active.	Active.
IIS2MDC magnetometer	Active.	Not used.
IST8308 magnetometer	Not used.	Active.
DLHRL20G airspeed	Constructed, but task disabled.	Not used.
MS4525 airspeed	Not used.	Active.
LLV3HP range sensor	Not used.	Active.
u-blox GNSS	Active.	Active.
PPS input	Active.	Active.
SBUS RC input	Active.	Active.
Telemetry UART	Active MAVLink transport.	Active by default.
USB VCP	USB task is started, but `BoardIo` uses the telemetry UART.	Optional MAVLink transport selected by `usb-vcp-serial`.
SD card	Task is started.	Task is started.
ADIS16500 IMU	Shared driver available; not initialized by either board.	Shared driver available; not initialized by either board.

Pixracer Pro Validation Record¶

The repository offers a bench test for recording a 10-second Pixracer Pro HAL UART run at 921600 baud. The following results demonstrate the rates tested by our team using this benchmarking:

Check	Recorded result
Valid MAVLink frames	`6420`
Packet integrity	Zero CRC errors, sequence gaps, estimated missing frames, or duplicates.
IMU	`399.5 Hz` host rate and `399.4 Hz` board-timestamp rate.
Attitude	`50.0 Hz`.
Barometer	`25.0 Hz`.
RC	`100.0 Hz`.
Output raw	`50.0 Hz`.
Status	`10.0 Hz`.
Heartbeat	`1.0 Hz`.
TIMESYNC	`5.0 Hz`.
Request/response paths	Command acknowledgement, version response, and `334` parameter-response frames were observed.
Firmware loop timing	Approximately `406.2 us` average and `468 us` maximum within the `2.5 ms` control period.
Scope timing	BMI08x production and foreground IMU consumption remained at `400 Hz`; measured producer-to-consumer latency was below `100 us`.

This run also injected ground-station heartbeat and TIMESYNC messages plus version and parameter requests.

Repeating the acceptance test¶

Use the repository tester with the serial device for your adapter:

python3 tools/mavlink_tester.py \
  --transport uart \
  --device /dev/serial/by-id/YOUR_ADAPTER \
  --baud 921600 \
  --duration-s 10 \
  --warmup-s 0.5 \
  --diagnostics \
  --acceptance \
  --expect-imu-hz 400 \
  --expect-rc-hz 100 \
  --expect-attitude-hz 50 \
  --expect-output-raw-hz 50

The acceptance mode injects heartbeat, TIMESYNC, version, and parameter requests and fails when required telemetry or replies are missing. It does not enforce every expected rate, so inspect the reported rates as well as the final pass/fail result.

For timing captures, flash the diagnostic build:

cargo xtask flash-board pixracerpro --scope-timing-pins

The feature does not permanently assign meanings to the test pins. Add temporary pin transitions around the code being measured, record the assignment with the capture, and remove the temporary instrumentation afterward.