Скачать или смотреть Dynamically Update Label Values in Tkinter

Learn how to dynamically change label values in Tkinter with real-time sensor data. This blog provides a clear solution for reading temperature values from a BME280 sensor and displaying them.
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This video is based on the question https://stackoverflow.com/q/62850241/ asked by the user 'Yannis Xidianakis' ( https://stackoverflow.com/u/13911992/ ) and on the answer https://stackoverflow.com/a/62852612/ provided by the user 'Eric Mathieu' ( https://stackoverflow.com/u/8629410/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Dynamically Update Label Values in Tkinter: A Step-by-Step Guide

As a newcomer to Python programming, navigating GUI applications can seem daunting. One of the common tasks you might encounter is displaying sensor data in real-time using Tkinter, Python’s standard GUI toolkit. If you’re working with a BME280 sensor to read temperature data, you may be puzzled about how to update the value displayed in a label widget dynamically. In this post, we will break down how to accomplish this effectively.

The Problem: Static Data Display

In the initial setup, you may notice that the temperature reading displayed in the label does not change even though the sensor readings may vary. This can be frustrating, especially when your goal is to update the displayed data every 30 seconds as the sensor acquires new temperature measurements.

Here’s a snippet of what your initial code might look like:

[[See Video to Reveal this Text or Code Snippet]]

What’s Going Wrong?

The key issue lies in the fact that you're only retrieving the temperature once when the application starts and never again. Therefore, any changes in the temperature reading from the sensor won't be reflected in your label.

The Solution: Update the Label Dynamically

To update the displayed temperature value dynamically, we can introduce a function that reads the sensor data and updates the label at specified intervals. Let’s break this down into clear steps:

Step 1: Create an Update Function

We will define a function called update_temp. This function will retrieve the latest temperature data from the BME280 sensor and update the StringVar associated with the label.

Step 2: Schedule the Update Function

Using the after method in Tkinter, we can set the application to call our update_temp function every 30 seconds.

Updated Code Example

Here’s how your updated code will look:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code Changes

Function Definition: update_temp is defined to get updated temperature values from the BME280 sensor.

Updating the StringVar: The line tempvar.set(...) inside update_temp ensures that each time the function is called, tempvar pulls the latest temperature reading.

Periodic Updates: main.after(30000, update_temp) is called to start the loop of fetching and updating the temperature reading every 30 seconds.

Conclusion

By following these steps, you can now successfully update the label in your Tkinter application dynamically as new temperature readings come in from your BME280 sensor. This approach not only keeps your display current but also enhances user engagement with real-time data. Happy coding!