# Airport Wind Station — STM32 Nucleo WB55RG I/O Mapping

These signals connect the Airport Wind Station simulation to the STM32 Nucleo
WB55RG through the LabsLand laboratory interface. They are not instructions
for wiring arbitrary external hardware. All command and sensor bits are
active high. Mbed spells pin `PA6` as `PA_6`; STM32 HAL uses port GPIOA and
pin `GPIO_PIN_6`.

## Simulation to STM32

- **Fixed slot 0 — Reserved:** `PC13` (Mbed `PC_13`). Ignore; not the controller reset.
- **Fixed slot 1 — `inputCode[0]`:** `PA6` (Mbed `PA_6`). Least-significant wind-code bit.
- **Fixed slot 2 — `inputCode[1]`:** `PB9` (Mbed `PB_9`). Most-significant wind-code bit.
- **Fixed slot 3 — Reserved:** `PB8` (Mbed `PB_8`). Ignore.
- **Fixed slot 4 — `aligned`:** `PC12` (Mbed `PC_12`). High when the turbine is aligned with the wind.

## STM32 to simulation

- **Fixed slot 0 — `align`:** `PC4` (Mbed `PC_4`). Request yaw toward the wind.
- **Fixed slot 1 — Reserved:** `PD0` (Mbed `PD_0`). Drive low.
- **Fixed slot 2 — `generatorEnable`:** `PD1` (Mbed `PD_1`). Request generation.
- **Fixed slot 3 — `active`:** `PB0` (Mbed `PB_0`). Turbine active.
- **Fixed slot 4 — `runwayWindAlert`:** `PB1` (Mbed `PB_1`). High-wind alert.

Preserve all five slots in each direction, including the unused ones. Configure
the sensor pins as inputs and command pins as outputs. Initialize outputs low
before running the controller. Never configure a simulation-driven input as an
output. In HAL, enable the GPIO port clocks before initialization.

## Wind encoding and timing

Combine the inputs as `(PB9 << 1) | PA6`: `01` calm, `10` steady, `11` high
wind, `00` reserved/non-generating safe stop. Generation requires steady wind
and confirmed alignment. The usage guide on the
[simulation page](https://redtail.rhlab.ece.uw.edu/simulations/airport-wind-station) defines the complete
operating requirements.

Advance the state machine once per second with a non-blocking timer, while
continuing to sample the inputs and update the high-wind alert. The Mbed
reference samples approximately every 5 ms; do not put the whole controller
behind a one-second blocking delay. Keep the reserved output `PD0` low.

## Controller reset

Use the target's normal reset/reboot mechanism. Start the controller in
STOPPED with yaw, generation and active commands low; then respond to the
current plant inputs. No external reset input is assigned to `PC13`.

The browser's **Restart activity** button resets the simulated plant, not the
STM32 program. Conversely, resetting the STM32 does not reset the wind or
turbine geometry. Test both operations separately.

## Credits

Airport Wind Station is a REDTAIL activity developed with RHLAB at the
University of Washington and integrated with LabsLand. 3D modeling and simulation
development: **Zhiyun (ZZ) Zhang**. Concept development, firmware development and
system integration: **Luis Rodríguez Gil**. Contributions to the activity
specification: **Brian Chap**. Project leadership and direction, and REDTAIL
principal investigator: **Professor Rania Hussein**. See the usage guide for full
acknowledgments.