wifi/scan/mcu_host

# Wi-Fi scan — Host

Scan for nearby Wi-Fi access points and print SSID, RSSI, channel, and auth mode for each, radio on the **coprocessor**, application on the **host**. `mcu_host/main/scan.c` is a byte-for-byte copy of upstream IDF `wifi/scan`. The example runs a single blocking scan and exits — convenient as a smoke test for the radio link.

## Supported Platforms and Transports

### Supported Coprocessors

| Coprocessor | ESP32 | ESP32-C Series | ESP32-S Series |
| :----------: | :---: | :------------: | :------------: |
| Support     | Yes   | Yes            | Yes            |

### Supported Host Devices

| Host Device | ESP32-P4 | ESP32-H2 | Other MCUs | Linux |
| :---------: | :------: | :------: | :--------: | :---: |
| Support     | Yes | Yes | [Yes](https://github.com/espressif/esp-hosted/blob/master/docs/getting-started-mcu.md) | [Yes](https://github.com/espressif/esp-hosted/blob/master/docs/getting-started-linux.md) |

### Supported Connection buses

| Connection bus | SDIO | SPI Full-Duplex | SPI Half-Duplex | UART |
| :------------- | :--: | :-------------: | :-------------: | :--: |
| Linux host     | Yes  | Yes             | No              | No   |
| MCU host       | Yes  | Yes             | Yes             | Yes  |

## Scenario

A scan is a request/event pair on the control path: the host asks the co-processor to scan, then reads the AP records.

```mermaid
sequenceDiagram
    participant App as Host app
    participant CP as Co-processor (Wi-Fi)
    App->>CP: esp_wifi_scan_start() (RPC)
    CP->>CP: scan channels
    CP-->>App: SCAN_DONE (RPC event)
    App->>CP: esp_wifi_scan_get_ap_records() (RPC)
    CP-->>App: list of nearby APs
```

Select the transport (must match the co-processor) and set the scan options:

```bash
cd examples/wifi/scan/mcu_host
idf.py set-target esp32p4
idf.py menuconfig
```

```text
Component config
└── ESP-Hosted
     └── Configure host
          └── Host transport
               ├── Communication bus (co-processor <== bus ==> host)
               │    ├── ( ) SPI Full Duplex
               │    ├── (X) SDIO                    <── default (match the co-processor)
               │    ├── ( ) SPI Half Duplex
               │    └── ( ) UART
               └── SDIO Configuration               ← slot, bus width, GPIOs (defaults OK)
```

```text
Example Configuration
├── (10) Max size of scan list
└── [ ] Scan only non overlapping channels using Channel bitmap
```

Host dependency config is **pre-set in `mcu_host/sdkconfig.defaults`** (do not remove):

```text
CONFIG_ESP_HOSTED_HOST_FEAT_RPC=y          # RPC control path to the CP
CONFIG_ESP_HOSTED_HOST_FEAT_RPC_EXT_V2=y   # RPC ext-v2 wire (required)
CONFIG_ESP_HOSTED_HOST_FEAT_SYSTEM=y       # system RPCs
CONFIG_ESP_HOSTED_HOST_FEAT_WIFI=y         # host Wi-Fi feature — routes esp_wifi_* to the CP
```

Then flash and monitor:

```bash
idf.py -p <host_usb_serial_port> flash monitor
```

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