# Machine configuration

When you add components through the Viam app, you’re building a JSON configuration that tells `viam-server` what hardware is attached and how to talk to it. Understanding this configuration structure helps you work faster. You can edit JSON directly, copy configurations between machines, and debug issues by reading the raw config.

## Configuration blocks

Every component in your machine’s configuration is a JSON block with these fields:

| Field | What it does |
| --- | --- |
| `name` | A unique name for this component on this machine. Your code references the component by this name. |
| `api` | The component type, in the form `rdk:component:<type>` (for example, `rdk:component:arm`). |
| `model` | The specific implementation, in the form `namespace:family:name` (for example, `viam:ufactory:xArm6`). Built-in models use `rdk:builtin:name` (for example, `rdk:builtin:gpio`). |
| `attributes` | Model-specific settings that control how to connect to the hardware and how it should behave. |
| `depends_on` | Other components this one requires (for example, a motor depends on a board). |
| `frame` | Optional spatial relationship to a parent component, used by the motion service. |

### Example: a motor controlled by a board

Here’s a simple configuration with a Raspberry Pi board and a DC motor connected to its GPIO pins:

```json
{
  "components": [
    {
      "name": "my-board",
      "api": "rdk:component:board",
      "model": "viam:raspberry-pi:rpi5",
      "attributes": {}
    },
    {
      "name": "my-motor",
      "api": "rdk:component:motor",
      "model": "gpio",
      "attributes": {
        "pins": {
          "a": "13",
          "b": "15",
          "pwm": "12"
        },
        "board": "my-board"
      }
    }
  ],
  "modules": [
    {
      "type": "registry",
      "name": "viam_raspberry-pi",
      "module_id": "viam:raspberry-pi",
      "version": "latest"
    }
  ]
}
```

A few things to note:

- **The board** uses `viam:raspberry-pi:rpi5` from the [Viam registry](https://app.viam.com/registry). The `modules` section tells `viam-server` to download and run that module. Other Pi variants (`rpi`, `rpi4`, `rpi3`, and so on) are available from the same module.
- **The motor** uses `gpio`, a built-in model for DC motors driven by GPIO pins. The `pins` attribute maps the motor’s control wires to specific board pins.
- The motor’s `board` attribute references `my-board`, so `viam-server` automatically initializes the board before the motor. An explicit `depends_on` field is not required when attributes already reference the other component.

### Modules section

When you use a model from the [Viam registry](https://app.viam.com/registry) (not built into `viam-server`), your configuration includes a `modules` section that tells `viam-server` what to download:

| Field | What it does |
| --- | --- |
| `type` | Always `"registry"` for modules from the Viam registry. |
| `name` | A local name for the module (used in logs). |
| `module_id` | The registry identifier, in the form `namespace:module-name`. |
| `version` | The version to use. Use a specific version for production; `"latest"` for development. |

You don’t need to write this JSON by hand. When you add a module model through the Viam app, the modules section is created automatically.

## Editing configuration

You can edit your machine’s configuration in two ways:

- **Builder UI**: the visual editor in the Viam app. Best for adding components one at a time and using form fields for attributes.
- **JSON mode**: click **JSON** in the left-hand menu on the CONFIGURE tab to see and edit the raw JSON. Best for copying configurations, making bulk changes, or understanding exactly what’s configured.

Both views edit the same underlying configuration. Changes in one are reflected in the other.