Arduino Project: how to use 10 segment LED Bar Graph Display with Arduino

Description:

In this article, we will explore the world of LED bar graph displays and how they can be used in conjunction with an Arduino microcontroller to create a range of visually stunning displays. We will cover the basics of LED bar graph displays, including how they work and how to connect them to an Arduino board. We will also walk through the steps involved in programming the Arduino to control the LED bar graph display and display data in a meaningful way. In my upcoming articles, I will provide practical examples of how LED bar graph displays can be used in real-world applications, including audio level meters, temperature displays, and more. By the end of this article, you will have a solid understanding of how LED bar graph displays work with an Arduino and how to create your own custom displays for your projects.

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Arduino Uno

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Led Bar Graph

Resistors

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Jumper wires

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What is Led Bar Graph?

A LED bar graph is a series of LED lights arranged in a linear or rectangular pattern that displays information visually. Each LED light represents a specific level or quantity of a variable, such as volume, temperature, or pressure. These lights can be programmed to turn on or off in various configurations to create different visual displays.

The LED bar graph is a popular component in electronics projects due to its simplicity, versatility, and ease of use. It can be used in a wide range of applications, including audio level meters, temperature monitors, and battery charge indicators. It provides a quick and easy way to display information that can be read at a glance, without the need for complex displays or computer screens.

The LED bar graph consists of a series of individual LED lights arranged in a linear or rectangular pattern. The number of lights in the bar graph can vary, depending on the application. The LEDs are typically arranged in a straight line or a rectangular shape, with each LED representing a specific level or quantity of the variable being monitored.

LED bar graphs can be either common cathode or common anode. In a common cathode LED bar graph, all the cathodes of the LEDs are connected together, while in a common anode LED bar graph, all the anodes of the LEDs are connected together. The type of LED bar graph used will depend on the specific application and the requirements of the project.

To use an LED bar graph in a project, it must be connected to a power source and a microcontroller such as an Arduino. The microcontroller is programmed to control the LED bar graph, turning on or off individual LEDs in response to changes in the variable being monitored.

Programming the LED bar graph involves determining the thresholds for each LED. For example, if the LED bar graph is being used as an audio level meter, each LED might represent a specific range of decibels, such as 0-10 dB, 10-20 dB, and so on. When the audio signal reaches a specific threshold, the corresponding LED will turn on, indicating the current volume level.

In addition to being used in electronics projects, LED bar graphs can also be found in a variety of consumer products. They are often used in car dashboards to display speed or fuel level, in home appliances to display temperature or humidity, and in sound systems to display volume or bass level.

the LED bar graph is a simple yet effective way to visually display information in a range of applications. Its versatility, ease of use, and low cost make it a popular choice for electronics hobbyists and professionals alike. With the right programming, an LED bar graph can be used to create a variety of visual displays that provide quick and easy access to important information.

Types of Led Bar Graph display:

There are several types of LED bar graphs available, each with its own unique characteristics and applications. Some of the most common types of LED bar graphs include:

• Linear Bar Graph: This is the most common type of LED bar graph and consists of a series of LEDs arranged in a straight line. The linear bar graph can display a range of data in a simple and easy-to-read manner. It is commonly used in audio level meters, battery charge indicators, and other similar applications.
• Circular Bar Graph: A circular bar graph consists of a series of LEDs arranged in a circular pattern. It is commonly used in applications where a radial display is more appropriate than a linear one. Examples include speedometers, tachometers, and other similar applications.
• Rectangular Bar Graph: A rectangular bar graph consists of a series of LEDs arranged in a rectangular pattern. It is commonly used in applications where a compact display is required, such as in portable electronic devices.
• Dot Matrix Bar Graph: A dot matrix bar graph consists of a matrix of individual LEDs that can be controlled individually to display custom patterns and images. It is commonly used in signage, video displays, and other similar applications.
• Bi-Color Bar Graph: A bi-color bar graph consists of LEDs that can display two colors, typically green and red. It is commonly used in applications where two states need to be displayed, such as ON/OFF or good/bad.
• Tri-Color Bar Graph: A tri-color bar graph consists of LEDs that can display three colors, typically red, green, and yellow. It is commonly used in applications where three states need to be displayed, such as low/medium/high or stop/caution/go.

In summary, the choice of LED bar graph type will depend on the specific application requirements, including the range of data to be displayed, the display format, and the available space. Each type of LED bar graph has its own unique characteristics and applications, making it important to select the right type for the task at hand.

How does LED Bar Graph Display Work?

An LED bar graph display works by using a series of LEDs to display information in a linear or stacked form. The LEDs are arranged in a row or column, and each LED corresponds to a particular value or data point.

When activated, the LEDs light up in a specific pattern to represent the information being displayed.

The basic working principle of an LED bar graph display is based on the behavior of LEDs. LEDs are semiconductor devices that emit light when a current passes through them. Each LED has a specific voltage drop and current rating, which determines the amount of power required to make it light up.

In an LED bar graph display, each LED is connected in series with a resistor, which limits the current through the LED and prevents it from burning out. The resistors also ensure that each LED receives the same amount of current, which ensures that they light up uniformly.

The LEDs in an LED bar graph display can be controlled in various ways, depending on the application. For example, a simple LED bar graph display may be controlled by a potentiometer, which changes the voltage applied to the LED array and changes the brightness of the LEDs accordingly. A more complex LED bar graph display may be controlled by a microcontroller or driver chip, which can turn on and off individual LEDs to display different patterns or sequences of information.

The display patterns used in an LED bar graph display can vary depending on the application. For example, a bar graph display may use a linear pattern, where each LED corresponds to a particular value or data point on a scale. Alternatively, a stacked bar graph display may use a vertical or horizontal pattern, where each LED represents a portion of a larger value or data set.

Examples of Led bar graph display with Arduino:

An Arduino is a popular microcontroller board that can be used to control various electronics components, including LED bar graph displays. It is programmed using the Arduino software, which allows you to write code in a C-like language and upload it to the board to control its behavior.

To use a LED bar graph display with an Arduino, you will need a few components. These include:

An Arduino board (such as the Arduino Uno)

• A LED bar graph display
• Resistors (typically 220 or 330 ohms)
• Jumper wires

Example1: how to use led bar graph display with Arduino without an analog input

The first step is to wire up the LED bar graph display to the Arduino board. This involves connecting each LED in the bar to a digital pin on the board, as well as connecting each LED to a resistor to limit the current flowing through it. The exact wiring will depend on the specific LED bar graph display you are using, so it’s important to refer to its datasheet or documentation for guidance.

Simple Led bar graph Circuit Diagram

Once the LED bar graph display is wired up, you can write code for the Arduino to control it. This typically involves using the digitalWrite() function to turn on and off the individual LEDs based on the data being measured. For example, if you are using the LED bar graph display to show the current level of sound volume, you could use a microphone module to detect the sound level and then use if-else statements in your Arduino code to turn on the appropriate LEDs based on the volume level.

Simple Led Bar Graph with Arduino Code

Here’s an example code for a simple LED bar graph display with Arduino, which lights up the LEDs without analog input:

output:

Code explanation:

First, an integer array ledPins is declared which stores the pin numbers of the LEDs connected to the Arduino board. In this case, the array contains 10 elements, each corresponding to a different LED, with pin numbers 2 to 11.

The numLeds variable is then set to the size of the ledPins array divided by the size of a single element of the array, which gives the number of LEDs in the array. In this case, numLeds will be set to 10, since there are 10 elements in the ledPins array.

The ledLevel variable is then set to a default value of 10, which represents the maximum LED level.

In the setup() function, a for loop is used to set each pin in the ledPins array as an output pin using the pinMode() function.

In the loop() function, another for loop is used to iterate through each element in the ledPins array. If the index of the current element is less than ledLevel, the corresponding LED is turned on by setting its pin to HIGH. Otherwise, the LED is turned off by setting its pin to LOW.

After all of the LEDs have been set to the appropriate level, the code waits for one second using the delay() function. Then, the ledLevel variable is decreased by 1, which causes the next loop iteration to turn off one additional LED. If ledLevel becomes less than 0, it is reset to the maximum number of LEDs.

Overall, this code creates a bar graph effect where a set number of LEDs light up based on the current ledLevel value. If ledLevel is set to 10, then all 10 LEDs will light up, creating a full bar graph. If ledLevel is set to 0, then all 10 LEDs will be off, creating an empty bar graph. By varying the value of ledLevel, different levels of the bar graph can be displayed.

Example2: how to use led bar graph with Arduino using analog input(potentiometer):

Using a potentiometer as an analog input to control an LED bar graph display with an Arduino is a relatively simple and fun project. In this project, we will use an analog input to read the voltage value of a potentiometer and use this value to control the number of LEDs lit up on the bar graph display. The more the potentiometer is turned, the more LEDs will be lit up.

Led Bar graph control with potentiometer Circuit diagram:

First, let’s start with the potentiometer. The potentiometer will have three pins, with the middle pin connected to analog input A0 of the Arduino board. The other two pins of the potentiometer are connected to the 5V and GND pins of the Arduino board, respectively.

Next, let’s move on to the LED bar graph. The LED bar graph consists of ten LEDs, each of which is connected to a separate digital output pin of the Arduino board. In this case, the LEDs are connected to pins 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11.

To connect the LED bar graph to the Arduino board, you will need to connect the anode (positive) pin of each LED to a separate output pin of the board (pins 2-11), and the cathode (negative) pin of each LED to a common ground connection. You can use a resistor between each LED anode and its respective output pin to limit the current flowing through the LED and to protect the board from damage.

Led Bar graph control with potentiometer using Arduino code:

output:

Code Explanation:

This is an Arduino program that controls an LED bar graph using an analog input from a sensor, such as a potentiometer. Let’s break it down line by line:

This line creates an array called ledPins that stores the Arduino pins to which the LEDs of the bar graph are connected. In this case, pins 2 through 11 are used.

This line calculates the number of LEDs in the ledPins array by dividing the total size of the array by the size of its first element. This allows the program to know how many LEDs are connected to the Arduino.

This line sets the analog input pin that will be used to read the sensor’s value. In this case, the potentiometer is connected to pin A0.

This line declares a variable called sensorVal that will be used to store the sensor’s analog value.

This line declares a variable called ledLevel that will be used to store the number of LEDs to light up based on the sensor’s value.

This is the setup() function that runs once when the Arduino is powered on or reset. It sets the pins to which the LEDs are connected as outputs using a for loop that iterates over the ledPins array.

This is the loop() function that runs repeatedly while the Arduino is powered on. It reads the analog value of the sensor using analogRead() and maps the value to the number of LEDs to light up using map(). Then, it iterates over the ledPins array and turns on the LEDs up to the ledLevel using digitalWrite() with HIGH and turns off the rest of the LEDs using LOW. This creates a bar graph effect that corresponds to the sensor’s value.

Arduino LED Bar Graph Problems and its Solution:

There are a few common problems that can occur when using an LED bar graph display with an Arduino, along with some potential solutions:

Insufficient current:

LED bar graph displays require a relatively high amount of current to operate, and the Arduino’s output pins may not be able to provide enough current to fully light all of the LEDs. To address this, you can use a separate power supply for the LED bar graph, or add current-limiting resistors in series with the LEDs to reduce the amount of current they draw.

Incorrect wiring:

If the LED bar graph is not wired correctly, it may not light up at all or may display the wrong information. Double-check your wiring to ensure that each LED is connected to the correct pin on the Arduino.

Programming errors:

If your code is not written correctly, the LED bar graph may not display the information you expect or may not display anything at all. Make sure your code is properly written and that it is sending the correct signals to the LED bar graph.

Dim or uneven lighting:

If the LEDs in the bar graph are not lighting up uniformly or are too dim, this may be due to differences in their forward voltage requirements. You can address this by using LEDs with similar specifications or by adding individual current-limiting resistors to each LED to ensure they receive the correct amount of current.

Inaccurate readings:

 If you are using the LED bar graph to display sensor data, you may find that the readings are not accurate or do not correspond to the expected values. This may be due to problems with the sensor itself, or with the way you are reading the sensor data in your code. Double-check your sensor connections and make sure your code is correctly reading and processing the data.