Introduction
In today’s fast-paced world, combining convenience and functionality is essential. This is especially true when it comes to audio equipment. A crucial feature that many often overlook is variable volume control. In this article, we will delve into the significance of this feature in tuners and discuss its implementation.
The HD44780 Display
The HD44780 display is a widely used component in electronics projects. It offers a simple and efficient way to incorporate a display into a device. This article will explore the different features and capabilities of the HD44780 display.
Features of the HD44780 Display
The HD44780 display family includes various models that range from 8 to 80 characters in four rows of two columns or one row with larger characters. Each character is composed of a 5×7 pixel grid. These displays can be connected to a parallel eight-bit bus, but most modern versions have adopted the I2C bus for communication.
Using the HD44780 Display with an MCP23008 Expander
One example of incorporating an HD44780 display into a device is by using it with an MCP23008 expander. This cheap additional component allows us to save four lines of the bus and enables communication through the I2C bus. By connecting the display to the expander according to the provided schematic, we can easily control the display using the I2C bus.
Setting Up the HD44780 Display
To use the HD44780 display with the MCP23008 expander, we need to import the necessary libraries for I2C communication. Additionally, we need to install libraries specific to the display and expander. Once the libraries are set up, we can initialize the display with the expander. The address of the expander can be found in the schematic or datasheet. It is essential to ensure that the addresses of all the components connected in the system do not conflict.
The Basics
In this article, we will delve into the realm of menu displays and explore how to utilize an LCD screen to create an interactive menu. To begin, we need to address the initial set up and display configuration. By setting the cursor at the beginning and displaying relevant information, we can ensure that everything is visible to the user. It is important to note that these instructions are applicable to LCD screens functioning on a four-bit bus system.
Setting up a Proper Display
Now that we have covered the basics of LCD screen configuration, it’s time to move on to creating a menu. In our previous articles, we developed a project that focused on adapting a numeric display. While it is possible to use the adapted display, for the sake of clarity and logic in our sketch, we will now utilize a liquid crystal display. This way, the program number will be displayed on the LCD screen. If you find any remaining elements of the program unclear, I encourage you to refer back to our previous articles.
An Alternative Approach
We will be taking a slightly different approach this time by working directly with the final version. However, I will still guide you through the process step by step. Let’s begin by outlining our objectives. Our menu will consist of two rows, each accommodating 16 characters. As an example, we can arrange the menu in the following manner: the station frequency will be displayed at the top, followed by the program number, then the volume level, and finally, the RDS messages on the left side. We will implement these elements one by one, starting with the program number.
Implementing the Program Number
To start, we need to import all the necessary components. As demonstrated in the small program used to manage the LCD display, we will import the I2C and LCD libraries, as well as the configuration command. Additionally, do not forget to specify the exact dimensions of your LCD screen to ensure proper functionality.
The possibilities for creating a menu on an LCD screen are endless. By following these steps, you can create an interactive and visually appealing menu for your project. Remember to import the necessary components and define the dimensions of your screen accurately to achieve the desired results.
The Importance of Clearing the Introduction
When it comes to writing an article, it is considered good practice to start by clearing the introduction. While it may not be a necessary step, it sets a good tone for the rest of the article. Now that we have cleared the introduction, we can proceed to display the texts. Let’s get started!
Changing the Program Numbers
In this subheading, we will address how to change the program numbers that are saved in the memory. This process will be done within a subprogram. We will add another subprogram that starts by setting the cursor position on position 11. There, we will display the abbreviation “Pr:”, followed by a colon. Have you noticed that the format of this command draws patterns from the flash memory rather than the RAM? This saves us one byte per character. It may not seem like much, but it teaches us good habits.
Displaying the Program Number
Now, let’s display the program number. However, we won’t do it right away. Having more space on the display means we don’t have to limit ourselves to just one character. We can have more than 9 programs by making use of two digits. Currently, there are 29 programs, but feel free to input any number up to 99. Let’s return to the abandoned procedure. Before displaying the number, we need to convert it into a string representation. Otherwise, instead of numbers, we would see ASCII codes of the current program value. Earlier, I showed you an example of how to transform it after certain conversions. However, this time, we will do it in a classic way. This function converts a numeric value into a string, which can be easily displayed on the screen without any issues. However, it may not look aesthetically pleasing. Numbers smaller than 10 will be shifted to the left, leaving a gap behind. To address this, we add a line that identifies such values and adds a zero in front. This way, the first program will be displayed as “01,” which looks much better. After compiling the sketch, you will be able to see the current program number at the end of the display.
The Creation of Variable Volume
To begin with, let’s explore how variable volume control is established. In the potentiometer handling procedure, certain changes need to be made. Prior to this, full volume control would be identified as a zero value. By mapping the potentiometer values directly to the tuner board, we can ensure that when the potentiometer is turned to the left, the volume will increase accordingly. Now, we will send the actual Variable value and increment its value by one.
The Reasoning Behind Zero Volume
You may wonder why zero volume is chosen to represent silence when intuitive understanding indicates that zero means no sound at all. The reason behind this choice lies in the fact that tuners have a flaw – their zero volume level is not complete silence. Therefore, to truly represent silence, we will display zero volume when there is actually no sound. Additionally, we will remap the volume values from 0 to 15 to a range from 1 to 16.
Displaying Volume and Frequency
Now that we have established the variable volume control, we can move on to displaying it alongside the program number. The only change needed is where this value should appear. Instead of “Pr”, the display will now show “Vol”. Similarly, when manually tuning or changing programs, we need to refresh the value. The subprogram for displaying volume and frequency will look slightly different. We will set the cursor as usual and then add a delay – the purpose of which will be explained shortly. Since the frequency value is already being used to store station information in the memory, it needs to be formatted properly, as it consists of five digits without a decimal point. Thankfully, the tuner library has a function that returns a formatted string. However, it is worth noting that this data takes several milliseconds to update after a frequency change.
Understanding the Opinions Line
When it comes to displaying data on a screen, it is important to present it in a clear and concise manner. In the case of the Opinions Line, it allows us to display information without worrying about commas and the word “megahertz.” However, let’s go back to discussing how to use the tuning buttons. Instead of searching for the nearest station, let’s change their function to tune the radio by 100 kHz increments. This makes more sense when there are 29 programs available. To achieve this, we simply replace the digit “1” with the digit “0”. For those who still want to use the search function, they can leave the buttons as they are. I have also added a subroutine that displays dashes instead of program numbers. When we start tuning the radio, displaying the program number no longer makes sense. Therefore, when we enter the tuning mode by pressing the “Pr” shortcut, two dashes appear in this place.
Introduction to RDS
Another feature that this radio has is the RDS, which displays text embedded in the radio signal. I won’t go into detail on how this system works, as it is a topic for another article. In short, we can only display up to 8 characters at a time. The way the text is displayed can be quite chaotic and varies from station to station. Sometimes, legibility becomes questionable. Therefore, I have decided to limit the display to 8 characters in the bottom row of the screen. To decode the texts, we will use a library that may not have clear descriptions, but it gets the job done. As usual, we need to name the object, so I used the obvious name “rds” for this library. The procedure works in a slightly unconventional way, without direct references to the elements in the program. Here, we define a pair of subroutines, one for receiving data and the other for processing it. The main loop only contains implicit references to these subroutines.
The Journey to Programming
Entering the world of programming can be overwhelming at first, with complex lines of code and unfamiliar terminology. However, once one delves deeper into the subject, a sense of excitement and possibility arises. In this article, we will explore the journey into programming, discussing the challenges and rewards it brings.
The Maze of Data Access
When initially navigating through programming, one may find themselves landing in a labyrinth of data access. The availability of such information can be convoluted, leaving programmers searching for answers. Curiously, there seems to be a lack of clear explanations as to why certain processes should be executed in a specific manner. However, in the grand scheme of things, not every aspect needs to be fully understood. Some elements may remain as enigmatic black boxes, as long as they function properly.
The Power of Formatted Text
An essential aspect of programming lies in the ability to convey information effectively. Fortunately, in the last line of code, we can send already formatted text to the display. While the complexity of this procedure may derive from the extensive system of RDS Messages, which ultimately hold little significance, it is comforting to know that broadcasters can transmit their intended messages effortlessly. Although this system may primarily serve as a decorative feature, rather than a practical necessity, with careful organization, its potential could be maximized.
Unlocking the Secrets of Radio Broadcasting
Programmers often yearn for the ability to extract valuable information about the music being played on radio stations. However, this desire has remained unfulfilled for the majority. It seems that the information provided is limited, and obtaining critical details about the broadcasted music is exceptionally rare. Despite this shortfall, with persistence and innovation, programmers may someday uncover the secrets of the airwaves through clever adaptations to their own needs.
The Final Stitch
After hours of dedication and countless lines of code, we find ourselves nearing the end of the programming journey. However, there is still one last task to complete – the final touch. Let us explore the process of saving stations in memory. By adding commands that display a message indicating the successful station saving and then reverting back to the standard display after a second, we can achieve the desired functionality. With this, our radio programming project is complete.
An Idea, Not to be Copied
As we conclude this article, it is essential to emphasize that the presented concepts are merely preliminary ideas. They should not be mindlessly replicated but rather adapted to suit individual requirements. The world of programming thrives on innovation and creativity, and it is through personalization that its true potential is unleashed.
The HD44780 display is a versatile component that offers an easy way to incorporate a display into electronic projects. By using an expander like the MCP23008, we can save valuable lines on the bus and utilize the efficient I2C communication protocol. With a little setup and proper initialization, we can take full advantage of the capabilities of the HD44780 display.
Variable volume control plays a crucial role in tuners, allowing for a more customized and enjoyable listening experience. By implementing the necessary changes in the potentiometer handling procedure and utilizing the appropriate functions, we can enhance the functionality and convenience of audio equipment. So next time you use a tuner, remember the importance of variable volume control and its impact on your listening pleasure.
