> For the complete documentation index, see [llms.txt](https://ask.simplehw.eu/kb/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ask.simplehw.eu/kb/simple-api-6-generation/modes/wifi-user-modes/light-on-off-wifi.md).

# Light on/off WiFi

Light on/off WiFi is similar to the original mode as it detects light - a message is sent every time a predefined threshold (% of light detected) is crossed either way. Can be set up to detect a very low light percentage threshold - darkness and extreme darkness (useful for monitoring package opening in the night). All mode-specific events are sent with 3 MAC addresses for better localisation precision.

Light on/off WiFi

**Hex value:** 0x1A

**Use cases:** Monitoring electricity usage, buildings and rooms, detecting opening of packages, freezers, safeboxes etc. and more

**Devices that support this mode:** SimplePack Plus

**Required sensors:** Light sensor, WiFi module

**Mode-specific deltas:**

**Deltas** are mode-specific register values different from *register default values*.

| **Register (hex)** | **Default (hex)** | **Delta (hex)** | **Delta information** |
| ------------------ | ----------------- | --------------- | --------------------- |
| 0x04               | 0x41              | 0x06            | Sleep time decreased  |
| 0x36               | 0x00              | 0x05            | Light detection on    |

**Mode-specific events (uplink messages):**

For more information on what uplink messages (***mode-independent events***) and additional data from various sensors in the device (***appended payload***) can be sent regardless of mode and how to fine-tune message behavior (***alerts***), see *Mode-independent information and events.*

| **Hex** | **Event name**                  | **Alert** | **Event information**                                                   |
| ------- | ------------------------------- | --------- | ----------------------------------------------------------------------- |
| 0x90    | Light detected with WiFi 1/2    | 1         | <p>Light % over predefined threshold,<br>sent with 3 MAC addresses</p>  |
| 0x91    | Light detected with WiFi 2/2    | 1         |                                                                         |
| 0x92    | Darkness detected with WiFi 1/2 | 2         | <p>Light % under predefined threshold,<br>sent with 3 MAC addresses</p> |
| 0x93    | Darkness detected with WiFi 2/2 | 2         |                                                                         |

**Registers relevant for this mode:**

| **Hex** | **Register name**               | **Default value (hex)**                       |
| ------- | ------------------------------- | --------------------------------------------- |
| 0x36    | Light sensor measurement period | 0 seconds (0x00), **delta: 5 seconds (0x05)** |
| 0x43    | Light sensitivity hysteresis    | 5% of light (0x05)                            |
| 0x44    | Light sensitivity threshold     | 30% of light (0x1A)                           |
| 0x4C    | Light sensor detection delay    | 0 seconds (0x00)                              |

**Similar modes:**

| **Hex** | **Mode name**             | **Description**                           |
| ------- | ------------------------- | ----------------------------------------- |
| 0x0D    | Light on/off              | Original version of Light on/off, no WiFi |
| 0x3B    | Light on/off WiFi Atlas   | WiFi Atlas version of Light on/off        |
| 0x56    | Light on/off WiFi Precise | WiFi Precise version of Light on/off      |

**Switching to mode, arming and disarming information:**

Follow the *Basic Operations With SimpleHw Devices guide*, where you can also find information about LED behavior, relevant Sigfox messages and more.

Here’s what’s important for **Light on/off WiFi** messages:

* To set this mode, the downlink needs to include this mode register setting: **011A**
* The uplink messages need to begin with the mode hex as the first byte: **1A**
* When arming the device, you should see this message: **1A10**
* When the device is armed, it should send you these two bytes: **1A11**
* If you disarm the device via long press, you should receive this message: **1A14**