# Airport Wind Station — DE1-SoC I/O Mapping

These signals connect the Airport Wind Station simulation to the Altera
DE1-SoC through the LabsLand virtual GPIO bus. They are not instructions for
wiring arbitrary external hardware. All command and sensor bits are active
high. GPIO 28 is written as `V_GPIO[28]` in Verilog/SystemVerilog or
`V_GPIO(28)` in VHDL.

## Simulation to FPGA

- **Fixed slot 0 — Reserved:** `V_GPIO[28]`. Ignore; not the controller reset.
- **Fixed slot 1 — `inputCode[0]`:** `V_GPIO[29]`. Least-significant wind-code bit.
- **Fixed slot 2 — `inputCode[1]`:** `V_GPIO[30]`. Most-significant wind-code bit.
- **Fixed slot 3 — Reserved:** `V_GPIO[23]`. Ignore.
- **Fixed slot 4 — `aligned`:** `V_GPIO[24]`. High when the turbine is aligned with the wind.

## FPGA to simulation

- **Fixed slot 0 — `align`:** `V_GPIO[26]`. Request yaw toward the wind.
- **Fixed slot 1 — Reserved:** `V_GPIO[27]`. Drive low.
- **Fixed slot 2 — `generatorEnable`:** `V_GPIO[32]`. Request generation.
- **Fixed slot 3 — `active`:** `V_GPIO[34]`. Turbine active.
- **Fixed slot 4 — `runwayWindAlert`:** `V_GPIO[31]`. High-wind alert.

Preserve all five slots in each direction, including the unused ones. Never
drive the simulation-to-FPGA inputs from your controller.

## Wind encoding and timing

Read the wind code as `{V_GPIO[30], V_GPIO[29]}`: `01` calm, `10` steady,
`11` high wind, `00` reserved/non-generating safe stop. Generation requires
steady wind and confirmed alignment. The full operating rules are in the
usage guide on the [simulation page](https://redtail.rhlab.ece.uw.edu/simulations/airport-wind-station).

Use `CLOCK_50` and the supplied one-second clock-enable tick, with two-stage
synchronizers on the plant inputs. The high-wind alert follows the synchronized
wind code without waiting for that one-second tick. Do not replace the board
clock with a generated/gated clock.

## Controller reset and indicators

The standard wrapper uses active-high `V_SW[0]` for controller reset. Assertion
is asynchronous and release is synchronized; the controller and tick divider
reset together. During reset, the controller enters STOPPED with yaw,
generation and active commands low. The alert follows the wrapper's sampled
wind input. Resetting the controller does not restart the simulated weather.

The standard wrapper presents the state on `LEDR[1:0]`: `00` STOPPED,
`01` ALIGNING, `10` GENERATING, `11` STOPPING. The browser's **Restart activity**
button resets only the simulated plant. It is not a board-reset button.

## 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.