Скачать или смотреть Creating an Object from a Foreign Class in Arduino C+ + : A Guide

Learn how to create and manage objects in Arduino C+ + , particularly when dealing with foreign classes, like LiquidCrystal_I2C for custom LCD displays.
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Creating an Object from a Foreign Class in Arduino C+ + : A Guide

When working with Arduino, you may find the need to extend the functionalities of libraries or create custom classes to manage specific hardware features, such as an LCD display. In this guide, we will explore a common issue that developers face while creating an object from a foreign class in Arduino C+ + and provide a clear, structured solution to help you navigate through it. Let's dive in!

Understanding the Problem

You have a basic functioning LCD display connected to your Arduino Mega 2560. The code you used shows a simple message, "Hello", on the screen. However, you want to expand the functionality of your LCD display by creating a custom class, Lcd, to manage various operations related to the display.

The Current Setup

Here's a brief overview of the code structure you started with:

LCD Initialization:

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

Basic functions (setup and loop):

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

Transitioning to a Custom Class

In your transition to a custom class, you defined Lcd in separate header and source files. Here you planned to encapsulate the functionality of the LCD display. However, you encountered a problem where the display did not show any output despite the code compiling without errors.

The Core Issue

The Diagnosis: The main issue arises from the fact that you created a local instance of LiquidCrystal_I2C in the begin() method that shadows the class member named myLCD. Therefore, the member object remains uninitialized when the write() method is called. This could be why no output appears on the LCD after you attempt to display text.

The Solution

Step 1: Refactor the Constructor

To resolve this issue, we need to modify the constructor of the Lcd class. Instead of relying on default values, we should pass the necessary arguments (address, columns, and rows) as parameters to the constructor.

Here's how you can do that:

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

Step 2: Update the begin() Method

You should also change the begin() method to remove the local instance creation of myLCD. Instead, you'll rely on the class member that was already initialized through the constructor.

Here's the revised begin() method:

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

Step 3: Adjust the Main File

Finally, you’ll need to adjust how you instantiate your Lcd object in your main Arduino file to pass the required constructor arguments:

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

Conclusion

By following the outlined steps, you should now be able to successfully create an object from the LiquidCrystal_I2C class within your custom Lcd class in Arduino C+ + . This method allows you to encapsulate additional functionalities while maintaining clean and efficient code. With this understanding, you're now better equipped to manage and utilize LCD displays in your Arduino projects.

Happy Coding!

If you have further queries or need assistance with your code, feel free to leave a comment below. We’d love to help!