> For the complete documentation index, see [llms.txt](https://erdilrf.gitbook.io/erdilrf-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://erdilrf.gitbook.io/erdilrf-docs/installation-and-model-specific-units.md).

# Installation and model-specific units

The exact model controls frame interpretation and distance scaling. A shared frame header is not enough to select a parser or assume a common unit.

## Arduino installation

In Arduino IDE Library Manager, search for **ErdiLRF** and select **0.1.1**. With Arduino CLI:

```sh
arduino-cli lib update-index
arduino-cli lib install "ErdiLRF@0.1.1"
```

This installs the library; it does not install a board core, configure a UART or verify a connected module. The computer-only exercise on the next page does not require Arduino IDE or a board.

## Use the model's unit

In the published 0.1.1 implementation:

| Model definition                            | Conversion performed by `rawToMetres()`       |
| ------------------------------------------- | --------------------------------------------- |
| `ERDI_LRF50H`                               | `raw / 100.0f`                                |
| `ERDI_LRF50VB`                              | `raw / 1000.0f`                               |
| Family A entries with `ERDI_UNIT_DECIMETRE` | `raw / 10.0f`                                 |
| `ERDI_SPD1200D03`                           | `NAN`: scaling is undocumented in this source |

These are software definitions, not new measurements or universal specifications for all delivered units. Confirm the exact model, controlled manual revision and delivered configuration.

The generated raw count **4354** therefore becomes **43.540 m** under `ERDI_LRF50H` and **4.354 m** under `ERDI_LRF50VB`. Both values are calculated from the same input. They do not represent a sensor observing a target.

## Inspect a model before using it

`erdiGetModelInfo(model, &info)` returns false for an unknown model index. Validate any model selection supplied by a user or configuration file. Do not use an arbitrary integer as a model constant.

`erdiDefaultBaud()` returns `0` for `ERDI_SPD1200D03` in this release because the source documentation contains conflicting baud statements. Zero means that a usable default was not selected; it is not a baud rate to configure.

A software model entry does not establish a common supply voltage, TX/RX logic level, connector pinout or available interface. Confirm those separately before wiring. The synthetic example's 115200 serial-console setting, if using its Arduino sketch, is not the rangefinder's UART specification.