# Connect your Sidewalk device and view uplink metadata format
Connect your Sidewalk device

In this tutorial, you'll use the MQTT test client to test the connectivity and see messages exhanged between your end device and the AWS Cloud. To receive messages, in the MQTT test client, subscribe to the topic specified when creating the IoT rule for your destination. You can also send a downlink message from AWS IoT Core for Amazon Sidewalk to your device using the `SendDataToWirelessDevice` API operation. You can verify that the message was delivered by enabling the message delivery status event notification.

**Note**  
For information about connecting your hardware platform and setting it up, see [Provisioning and registering your end device](https://docs.sidewalk.amazon/provisioning/) and [Setting up the hardware development kit (HDK)](https://docs.sidewalk.amazon/getting-started/sidewalk-onboard-prereq-hdk.html) in the *Amazon Sidewalk documentation*.

## Send downlink messages to your end device


Use the [https://docs.aws.amazon.com/iot-wireless/latest/apireference/API_SendDataToWirelessDevice.html](https://docs.aws.amazon.com/iot-wireless/latest/apireference/API_SendDataToWirelessDevice.html) API operation or the [https://docs.aws.amazon.com/cli/latest/reference/iotwireless/send-data-to-wireless-device.html](https://docs.aws.amazon.com/cli/latest/reference/iotwireless/send-data-to-wireless-device.html) CLI command to send downlink messages from AWS IoT Core for Amazon Sidewalk to your Sidewalk end device. Following shows an example of how to run this command. The payload data is the binary to be sent, encoded in base64.

```
aws iotwireless send-data-to-wireless-device \
    --id "<Wireless_Device_ID>" \
    --payload-data "SGVsbG8gVG8gRGV2c2lt" \
    --wireless-metadata Sidewalk={Seq=1,AckModeRetryDurationSecs=10}
```

Following shows a sample output of running this command, which is an ID of the downlink message sent to the device.

```
{
    MessageId: "6011dd36-0043d6eb-0072-0008"
}
```

**Note**  
The `SendDataToWirelessDevice` API can return a message ID but the message might not be successfully delivered. To check the status of the message that was sent to the device, you can enable message delivery status events for your Sidewalk accounts and devices. For information about how to enable this event, see [Event notifications for Sidewalk resources](iot-wireless-events-notifications.md#iot-sidewalk-events). For more information about this event type, see [Message delivery events](https://docs.aws.amazon.com/iot/latest/developerguide/iot-sidewalk-message-delivery-events.html).

## View format of uplink messages from the device


After you've connected your device, you can subscribe to the topic (for example, *`project/sensor/observed`*) that you specified when creating the destination rule, and observe uplink messages from the device. 

If you specified a topic name when creating your destination, you can subscribe to the topic to monitor uplink messages from your end device. Go to the [MQTT test client](https://console.aws.amazon.com/iot/home#/test) on the **Test** page of the AWS IoT console, enter the topic name (for example, *`project/sensor/observed`*), and then choose **Subscribe**.

The following example shows the format of the uplink messages that are sent from Sidewalk devices to AWS IoT. The `WirelessMetadata` contains metadata about the message request.

```
{
   "PayloadData":"ZjRlNjY1ZWNlNw==",
   "WirelessDeviceId":"wireless_device_id",   
   "WirelessMetadata":{
      "Sidewalk":{
         "CmdExStatus":"Cmd",
         "SidewalkId":"device_id",
         "Seq":0,
         "MessageType":"messageType",
         "Timestamp": "2024-10-21T19:33:01.295912052Z",
         "Rssi": -22,
         "LinkType": "LoRa"
      }
    }
}
```

The following table shows a definition of the different parameters in the uplink metadata. The `device-id` is the ID of the wireless device, such as `ABCDEF1234` and the `messageType` is the type of uplink message that's received from the device.


**Sidewalk uplink metadata parameters**  

| Parameter | Description | Type | Required | 
| --- | --- | --- | --- | 
| PayloadData |  The message payload that is sent from the wireless device.   | String | Yes | 
| WirelessDeviceID | The identifier of the wireless device that's sending the data | String | Yes | 
| Sidewalk.CmdExStatus |  Command runtime status. Response-type messages shall include the status code, `COMMAND_EXEC_STATUS_SUCCESS`. However, notifications might not include the status code.  | Enumeration | No | 
| Seq |  The message sequence number.  | Integer | Yes | 
| Sidewalk.NackExStatus |  Response nack status, which can be `RADIO_TX_ERROR` or `MEMORY_ERROR`.   | Array of strings | No | 
| Timestamp |  The time when the Sidewalk device sent an uplink request.  | Timestamp | Yes | 
| Rssi |  Received Signal Strength Indicator, which is a measurement of a wireless network's signal strength  | Integer | No | 
| LinkType |  The type of link that was used to perform the uplink which can be one of `LoRa`, `BLE`, or `FSK`  | String | No |