> For the complete documentation index, see [llms.txt](https://docs.blynk.io/en/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.blynk.io/en/blynk.console/templates/events/custom-events/events--how-to-log-events.md).

# How to Send/Log Events

## Send events using Firmware API

If you need to log an Event when the sensor detects temperature over a certain threshold:

1. Create a new Event named `High temperature` with code `high_temp`
2. Use the `Blynk.logEvent(event_code)` firmware API command to trigger new event

```cpp
if (temperature > 35)
{
   Blynk.logEvent("high_temp");
}
```

When this code worked, an Event will be logged and the system will act accordingly to the Event setup (render on timeline, send notifications, etc.)

### Custom Event Description

You can change the description of the event when it's rendered on the timeline in Blynk.Console and in Blynk.Apps.

```cpp
if (temperature > 35)
{
  Blynk.logEvent("event_code", String("High TemperatureDetected! Tº: ") + temp);
}
```

{% hint style="warning" %}
Make sure you enabled [Timeline recording](/en/blynk.console/templates/events/custom-events/events-general-setting.md#show-event-on-the-timeline) in the Event Settings to see the result in the apps
{% endhint %}

## Send events using HTTPS API

To log an event use this request

```
`/external/api/logEvent?token={AuthToken}&code={event_code}
```

```
`/external/api/logEvent?token={token}&code={event_code}&description={event_description}
```

```
/external/api/logEvent?token={device_token}&code={event_code}&description={event_desciption}
```

`description` is an optional parameter where you can attach additional information to be rendered on the Timeline along with the event.

For example:

```
https://my.server.com/external/api/logEvent?token=Q9qdlGahPuFuCfncrT35QutT7s3HjYFy&code=high_temp
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.blynk.io/en/blynk.console/templates/events/custom-events/events--how-to-log-events.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.