# Events Events are used to track, log, and work with important events that happen on the device. Events are also used for notifications which can be sent over email, delivered as push notifications to the user's smartphone, or sent as an SMS. Events are pre-configured in Blynk.Console and can be triggered with a [Events Firmware API](/en/blynk-library-firmware-api/log-event.md) from the device or using [Events HTTP API](/en/blynk.cloud/device-https-api/trigger-events-api.md). *Examples of an Event:* * *Log a moment when a temperature reaches a certain threshold and send a notification to selected users* * *Track the total working hours of the device. If it approaches or goes beyond a maximum value, you would need to notify technical support so that they can replace the device or provide warranty service*

Events list in the template

## Types of Events There are three types of Events in Blynk: * **System Events:** Default Blynk platform events, like "OTA Update" * **Custom Events:** Events you can create and configure for your needs * **Content Events:** Informative events that are shown separately in the app ### System Events You can't delete the system events or edit them. #### Firmware Over-The-Air Update status This is a system event to track firmware updates. It can't be configured. ### Custom Events These are Events you can configure based on what your device does. Read these articles to start logging events and sending notifications: * [**Event Settings**](/en/blynk.console/templates/events/custom-events/events-general-setting.md) * [**How to send custom events from hardware using Firmware API and HTTPS API**](/en/blynk.console/templates/events/custom-events/events--how-to-log-events.md) * [**Content Events**](/en/blynk.console/templates/events/custom-events/events-content-events.md) ## How to log an event in Blynk ### 1. [Create a Template](/en/getting-started/template-quick-setup.md) or use an existing one ### 2. Create a New Event Go to Developer Zone -> My Templates -> Select a template -> Open the "Events & Notifications" tab. 1. Click **Edit** Template 2. Click **+ Create Event** 3. Name the first event with the name Hello 4. Click **Create** (the event will appear in the Events tab list) 5. Repeat the previous step for the second event with the name Error 6. Click **Save** to save and apply the changes made (select Update active device this time) {% hint style="info" %} Note that each event has`EVENT_CODE`. This event code will be used in firmware API or HTTPS API {% endhint %} ### Send Events Using Firmware API 1. Create a new Event named `High temperature` with code `high_temp` 2. Use the `Blynk.logEvent(event_code)` firmware API command to trigger a new event: ```cpp if (temperature > 35) { Blynk.logEvent("high_temp"); } ``` When this code works, an Event will be logged and the system will act accordingly to the Event setup (render on the timeline, send notifications, etc.) {% hint style="warning" %} Don't log an event too many times to avoid hitting daily limits. You can use timers or flags to mark the already-sent events. Check this [article](/en/getting-started/how-to-display-any-sensor-data-in-blynk-app.md) on how to avoid spamming the server with events {% endhint %} {% hint style="info" %} The current limit is 100 events per device per day. This limit could be increased for Enterprise clients to fit their needs. {% endhint %} #### 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. For example, you can include the current data ```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 via GET request: ``` `/external/api/logEvent?token={AuthToken}&code={event_code} ``` To add a custom description to the event, use this GET request ```html `/external/api/logEvent?token={AuthToken}&code={event_code}&description={event_description} ``` Example: ``` https://blynk.cloud/external/api/logEvent?token=GVki9IC70vb3IqvsV0YD3el4y0OpneL1&code=firmware_update&description=test ``` ## ## 3. Sending Events You can test the Event creation by sending it from Device using Blynk.Edgent firmware API, or with REST API. ### Use Blynk.logEvent() firmware API `Blynk.logEvent("event_code", "optional message");` For this tutorial, you would need to use hello as a name. Here is a pseudo-code: ```cpp if (some_condition){ Blynk.logEvent("hello"); } ``` Optionally, you can send a custom description of the event. This description will be rendered on Device Timeline. ```cpp if (some_condition){ Blynk.logEvent("hello", "Hello World,") ; } ``` ### Use HTTP REST API 1. Navigate to the Device 2. Click on its name 3. Open the Device Info tab 4. Find Auth Token there and click on the icon to copy it to the clipboard

Device Info tab with Auth Token

![Auth Token. Click copy Auth Token pictogram here](/files/-MYk0r1xT2LHd994hV5K) Now make an HTTP request with the tools you use for that. Make sure to change the `AuthToken` to the one you copied in the previous step. You can even use your browser for that. Just put it in the URL field and press Enter. ```http https://blynk.cloud/external/api/logEvent?token=AuthToken&code=hello ``` Repeat the same with `code=error` ```http https://blynk.cloud/external/api/logEvent?token=AuthToken&code=error ``` ## 4. Checking if the Event was logged First of all, check [Device Timeline](/en/blynk.console/devices/device-profile/timeline.md) by going to Device -> Timeline tab ![Device Timeline tab](/files/-MYk2cm64KNekYzR5VwR) You should see 2 events on the timeline! If you set up notifications, they should have been delivered as well. ## Limitations * You can send only 100 events per device per day (Adjustable in Enterprise Plan) * When the limit is reached you'll see the notification on the UI in the Device Timeline section * The maximum description length for the event is 300 characters --- # Agent Instructions: 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: ``` GET https://docs.blynk.io/en/getting-started/events-tutorial.md?ask= ``` The question should be specific, self-contained, and written in natural language. 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.