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Document activelow and chip in gpio #1016

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24 changes: 17 additions & 7 deletions i18n/en/docusaurus-plugin-content-docs/current/devices/plugins.mdx
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Expand Up @@ -378,15 +378,20 @@ It is particularly suitable for Raspberry Pi and similar single-board computers.

**Parameters**:

| Parameter | Type | Required | Description |
| --------- | ------ | -------- | ---------------------------------------- |
| function | string | yes | Mode: `read` (input) or `write` (output) |
| pin | int | yes | Pin number (BCM numbering, e.g. GPIO 17) |
| Parameter | Type | Required | Description |
| --------- | ------ | -------- | ------------------------------------------------------------------ |
| function | string | yes | Mode: `read` (input) or `write` (output) |
| pin | int | yes | Pin number (BCM numbering, e.g. GPIO 17) |
| activelow | bool | no | If `true`, pin will be `true` when at 0 V and `false` at VCC. |
| bias | string | no | `as-is`, `disabled`, `pull-up` (default for `read`), `pull-down` |
| chip | string | no | GPIO device (default: `gpiochip0`) |

**How it works**:

- **Reading** (`function: read`): Reads the state of a GPIO pin as a boolean value (`true` = HIGH, `false` = LOW)
- **Writing** (`function: write`): Sets a GPIO pin to HIGH (`true`) or LOW (`false`)
- **Reading** (`function: read`): Reads the state of a GPIO pin as a boolean
value (`true` = HIGH, `false` = LOW, and the other way around if `activelow` is set)
- **Writing** (`function: write`): Sets a GPIO pin to HIGH (`true`) or LOW
(`false`), and vice-versa if `activelow`

Pin numbering follows the BCM scheme (Broadcom numbers, not the physical pin position).
For a Raspberry Pi pinout, see e.g. [pinout.xyz](https://pinout.xyz/).
Expand All @@ -399,6 +404,11 @@ function: read
pin: 17 # BCM pin number
```

:::note
For legacy reasons the default is active high *with internal pullup resistor*,
which means if you don't connect anything to the pin, it will be `1` aka `true`.
:::

**Writing Example**:

```yaml
Expand All @@ -408,7 +418,7 @@ pin: 27 # BCM pin number
```

:::note
This plugin only works on Linux systems with access to `/dev/gpiomem`.
This plugin only works on Linux systems with access to `/dev/gpiochip0`.
:::

### Go <Tag label="read" category="read" /> <Tag label="write" category="write" /> {#go}
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