> For the complete documentation index, see [llms.txt](https://docs.mclimate.eu/mclimate-lorawan-devices/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mclimate.eu/mclimate-lorawan-devices/devices/mclimate-vicki-lorawan/vicki-lorawan-device-communication-protocol/operational-modes-and-temperature-control-algorithm/d2d-communication.md).

# D2D communication

## D2D notification device AppKey

In order to be able to accept temperature and humidity data directly from the MClimate HT Sensor, its AppKey needs to be known to Vicki. You can configure the AppKey via the command below.

{% hint style="warning" %}
This command is applicable only when Vicki operates in [mode 03](/mclimate-lorawan-devices/devices/mclimate-vicki-lorawan/vicki-lorawan-device-communication-protocol/operational-modes-and-temperature-control-algorithm.md#device-operational-modes).
{% endhint %}

{% tabs %}
{% tab title="SET" %}

<table data-header-hidden><thead><tr><th width="135"></th><th></th></tr></thead><tbody><tr><td><strong>Byte index</strong></td><td><strong>Hex value - Meaning</strong></td></tr><tr><td>0</td><td>6F – The command code</td></tr><tr><td>1</td><td>AppKey byte 0 (Most significant)</td></tr><tr><td>...</td><td>...</td></tr><tr><td>16</td><td>AppKey byte 15 (Least significant)</td></tr></tbody></table>

**Example command:** `0x6F112233445566778899AABBCCDDEEFF` – Vick will accept data from the HT Sensor with AppKey `0x112233445566778899AABBCCDDEEFF`
{% endtab %}

{% tab title="GET" %}

<table data-header-hidden><thead><tr><th width="131.66666666666666"></th><th width="179"></th><th></th></tr></thead><tbody><tr><td><strong>Byte index</strong></td><td><strong>Sent request</strong></td><td><strong>Received response</strong></td></tr><tr><td>0</td><td>70 – The command code</td><td>70 –  The command code</td></tr><tr><td>1</td><td> </td><td>AppKey byte 0 (Most significant)</td></tr><tr><td>...</td><td>...</td><td></td></tr><tr><td>16</td><td></td><td>AppKey byte 15 (Least significant)</td></tr></tbody></table>

**Example command:** `0x70`

**Example response:** `0x70112233445566778899AABBCCDDEEFF` – Vicki will handle D2D data from the HT Sensor with AppKey `0x112233445566778899AABBCCDDEEFF`
{% endtab %}
{% endtabs %}

## Request listen for D2D notification device

This command instructs Vicki to listen for the D2D notification device AppKey again if for some reason the communication has been broken.

{% hint style="warning" %}
This command is applicable only when Vicki operates in [mode 03](/mclimate-lorawan-devices/devices/mclimate-vicki-lorawan/vicki-lorawan-device-communication-protocol/operational-modes-and-temperature-control-algorithm.md#device-operational-modes).
{% endhint %}

<table data-header-hidden><thead><tr><th width="135"></th><th></th></tr></thead><tbody><tr><td><strong>Byte index</strong></td><td><strong>Hex value - Meaning</strong></td></tr><tr><td>0</td><td>71 – The command code</td></tr></tbody></table>

**Example command:** `0x71`

## Temperature value got by HT Sensor

This command is used automatically when Vicki is in [mode 03](/mclimate-lorawan-devices/devices/mclimate-vicki-lorawan/vicki-lorawan-device-communication-protocol/operational-modes-and-temperature-control-algorithm.md#device-operational-modes), where the command code is automatically pre-pended to the keep-alive payload. This way one can distinguish that Vicki is in mode 03 via the payload itself and also extract the temperature reading of the HT Sensor.

{% hint style="warning" %}
This command is applicable only when Vicki operates in [mode 03](/mclimate-lorawan-devices/devices/mclimate-vicki-lorawan/vicki-lorawan-device-communication-protocol/operational-modes-and-temperature-control-algorithm.md#device-operational-modes).
{% endhint %}

<table data-header-hidden><thead><tr><th width="135"></th><th></th></tr></thead><tbody><tr><td><strong>Byte index</strong></td><td><strong>Hex value - Meaning</strong></td></tr><tr><td>0</td><td>72 – The command code</td></tr><tr><td>1</td><td>Temperature value – bits 15:8</td></tr><tr><td>2</td><td><p>Temperature value – bits 7:0</p><p>T,[C] = bits[15:0] / 10.</p></td></tr></tbody></table>

**Example command:** `0x7200F1` => T = `0x00F1` / 10 = 241 / 10 = 24.1 Celsius degrees.


---

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